bluuebunny/crossref_metadata_2025 huggingface dataset:
In-situ coating of silicon-rich films on tokamak plasma-facing components with real-time Si material injection
Authors: Effenberg F. , Abe S. , Sinclair G. , Abrams T. , Bortolon A. , Wampler W.R. , Laggner F.M. , Rudakov D.L. , Bykov I. , Lasnier C.J. , Mauzey D. , Nagy A. , Nazikian R. , Scotti F. , Wang H.Q. , Wilcox R.S. ,   the DIII-D Team
Published: August 2023

Experiments have been conducted in the DIII-D tokamak to explore the in-situ growth of silicon-rich layers as a potential technique for real-time replenishment of surface coatings on plasma-facing components (PFCs) during steady-state long-pulse reactor operation. Silicon (Si) pellets of 1 mm diameter were injected into low- and high-confinement (L-mode and H-mode) plasma discharges with densities ranging from 3.9–

7.5
×

10

19

m−3 and input powers ranging from 5.5 to 9 MW. The small Si pellets were delivered with the impurity granule injector at frequencies ranging from 4 to 16 Hz corresponding to mass flow rates of 5–19 mg s−1 (1–

4.2
×

10

20

Si s−1) at cumulative amounts of up to 34 mg of Si per five-second discharge. Graphite samples were exposed to the scrape-off layer and private flux region plasmas through the divertor material evaluation system to evaluate the Si deposition on the divertor targets. The Si II emission at the sample correlates with silicon injection and suggests net surface Si-deposition in measurable amounts. Post-mortem analysis showed Si-rich coatings containing silicon oxides, of which SiO2 is the dominant component. No evidence of SiC was found, which is attributed to low divertor surface temperatures. The in-situ and ex-situ analysis found that Si-rich coatings of at least 0.4–1.2 nm thickness have been deposited at 0.4–0.7 nm s−1. The technique is estimated to coat a surface area of at least 0.94 m2 on the outer divertor. These results demonstrate the potential of using real-time material injection to form Si-enriched layers on divertor PFCs during reactor operation.
Assessment of Water Quality of Al-Habbaniya Lake by Using Statistical Techniques (Cluster and Factor Analysis)
Authors: Al-Paruany Kamal B , Al-Kubaisi Mahmood H , Al-Heety Salam O , Jassaim Ali A
Published: August 2023

Habbanyia lake is one of the most crucial resources of water, water lake is used mainly for agriculture, animal activities, and drinking water purposes. In addition, it represents a tourist city. Multivariable statistical approach was used to assess the quality of the water of Habbanyia lake in west Baghdad, to determine how the physical and chemical qualities relate of lake water and the local trend of water type. R-mode and Q-mode cluster and factor analyses were used to categorize chemical characteristics and determine the variables influencing changes in quality. The results show, the water samples are considered to be Fresh water and all the lake water samples were within the WHO standard. In general, Ca-SO4 and Na-SO4 facies were the most prevalent in the Habbanyia Lake water. The results show, there are two factors controlling the water quality of Habbanyia lake, the first is geological sitting and the second is human activities.
Developing A Series of Weirs System to Improve Hydraulic Properties and Generate Hydroelectric Power in Rivers
Authors: Abdulhameed Isam M , Kamel Ammar H , Selman Mohammed
Published: August 2023

In present paper, attempts were made to develop a system of weirs along Euphrates River in Iraq to solve the problem of the deficit in power and water resources. Geometric numerical models were created with geographic information system (GIS) with digital elevation model (DEM). The model includes visual basic programming to evaluate the power potentials according to an economic methodology based on the cost-benefit ratio (CBR). It estimates the cost, power profits, and determines the optimal height and number of small dams along the study reach. A system of three dams with a (4.3 m) in height can generate expected power of (45 MW) within (99%) of CBR. The system is simulated with the numerical model (HEC-RAS) to evaluate the river behavior with minimum, average, and maximum discharge values (270, 543, 815 m3/s) and study the hydraulic effect on the river. The hydraulic properties improve by (28%), the average depth increase with (27%), and a decrease in the variation caused by discharge changes. The river tendency is to store water with limited expansion in the surface area. The average surface area expands with (5%), the average storage increase with (35 %) especially in cases of low discharges.
The Effect of Operating Pressures and Speed Ratios on The Evaluation Criteria of The Center Pivot Irrigation System (Valley) in Al Baghdadi Region
Authors: Al-Hashemi MJ , Al-Mehmdy SH
Published: August 2023

A study conducted during the 2021winter season in Al Baghdadi region (150) km west of Ramadi City (Iraq) to show the effect of operating pressure and equipment speed on evaluation criteria of the center Pivot Irrigation Systems. Three operating pressures were used in the experiment, which are 25, 30 and 35 pounds inch−2, with three speeds of 25%, 50% and 75% for each pressure. Study result showed that The pressure 30 pounds inch−2 achieved the highest values for the average of the studied traits, as it was 97.22% while the lowest value was recorded at a pressure 25 pounds inch−2 which amounted to 88.70% with a decrease Ratio 9.6%. The pressure 35 pounds inch−2achieved the lowest average water depth 24.13 mm, while the highest average depth of water was at pressure 30 pounds inch−2 35.89 mm with a height Ratio 32.7%. The lowest average value of the water depth variance (qvar.) was 8.34% at pressure 30 pounds inch−2 while the average of this value increased to 28.63% at pressure 35 pounds inch−2 with increase 70.8%. The ratio of the rotational speed of the arm of the system significantly affected the values of each of the studied traits, the velocity 25% achieved the highest average values 30.93 mm and 93.10%, while the speed 75% achieved the lowest rate 26.58 mm and 89.63% With a decrease 16.4% and 3.8% for each of the applied water depth and Uniformity coefficient, respectively. This speed 25% also achieved the lowest average water depth variance, which amounted to 16.02%, while speed75%achieved the highest value of water depth variance, which amounted to 26.59%, with an increase rate 39.7%.
Simulation Design and Analysis for Water Network Inside Building Using Elite(S-Pipe) Software
Authors: Mohammed Mohammed K. , Al-Obaidi Basim H.
Published: August 2023

Humanity is looking for a way to face the problems of lack of habitable land, and the vertical housing method and multi-story buildings was the most appropriate solution for housing a large number of residents in the same space. In this study, the work was to analyze the existing design and re-design for the water supply network inside the building in Bismayah city consists of multi-story buildings of 10 floors, and each floor consists of 12 apartments, 100,000 housing units for the whole city. The water supply network inside the buildings is the only source of water for the residents in the city for drinking and use in various daily activities, taking care of the design of this network guarantees the success of the city. The results showed that the riser pipe in the water supply network inside the building had a diameter range from (3 to 1.5) inches, while the redesign was done by manual calculations and Elite(S-Pipe) software according to the International Plumbing Code 2021. The pipe diameters ranged from (2 to 1) inch, also the main horizontal pipe feeding the riser pipes in the network has a diameter of (4) inches, while the redesign showed the pipe with a graduated diameter from (3 to 2) inches. In general, the study showed that the used diameters are larger than the designed diameters according to the International Plumbing Code 2021, which will negatively affect the performance of the water supply network inside the buildings, in addition to increasing the cost of the network.
Effect of Surface Drip Irrigation and Polymer Addition on Some Physical Soil Characteristics, Growth and Yield Characteristics of Cauliflower
Authors: Hussein Hassan A , Aldulaimy Saad E
Published: August 2023

The study was conducted during the fall season at the research station of the University of Anbar - College of Agriculture, cauliflower seedlings were planted on 10/2/2021 in a soil with a sandy loam mixture texture, this research aimed to study the effect of the two irrigation methods, which are surface drip irrigation (IC) and partial drying of the soil surface (IP) and the addition of polymer in the following proportions, They are without adding MO, 0,3%ML, and 0,6%MH in bulk density, porosity, weighted diameter, plant height, leaf area, and total yield, The experimental treatments were distributed using the factorial experiment within the randomized complete block, and the results of the study showed that the method of partial drying of the soil surface was significantly superior to the rest of the treatments by giving it the lowest average of the bulk density values 1,25 mg,g-3 and the highest average of the porosity values at 50,79%, and an increase in the average values of the weighted diameter, plant height, leaf area and total yield at 0,36 mm, 50,33 cm, 10,58 dm plant-1 and 33,61 tons ha-1, respectively, The effect of the polymer treatments on the above traits, the polymer addition treatment was significantly superior by 0,6% by giving it the lowest apparent density at 1,22 Mg,g-3 and the highest mean of the porosity values, which was 52,17%, 11,79 dm per plant-1 and 34,17 tons per hectare-1, respectively,
Improving the Discharge Capacity of the Al Butera River
Authors: Alhamdi Hashim M , Al Thamiry Hayder A
Published: August 2023

In the province of Maysan, the Al Butera River is one of the most significant tributaries of the Tigris River. It has a length of 48.8 km and reaches the Central Marshes in the south of Maysan from downstream of Al Butera Regulator. Villages and farmland suffer significant. The purpose of this project is to examine and enhance the Al Butera River, which has suffered harm from sedimentation and bank encroachment, particularly during the flooding in April 2019.. Using the available cross-sections and hydraulic data from numerous Ministry of Water Resources. Iraq sectors, a one-dimensional hydraulic model simulating the flow in the Al Butera River was created using the HEC-RAS 5.0.7 software. The fieldwork was conducted to fill in any gaps in the data that were there regarding the river. Fieldwork includes doing an inspection and measuring outflow. Using calibration and verification with a low root mean square error, the simulation demonstrated that Manning’s coefficient is 0.026. Additionally, the Al Butera River has a current capacity of 170 m3/s with the current flood escapes, while its developed capacity for short-term development by raising the banks level is 250 m3/s. However, the river’s long-term development through cross-section alteration with bank-level maintenance is 400 m3/s and does not allow for flood escape. Because there are pavements and populated areas nearby, raising the banks of the Al Butera River by around 2 m would be necessary to develop it to handle the design discharge of 700 m3/s.
Comparison of Unsaturated Hydraulic Conductivity Calculated by Jackson Equation and Van Genuchten Equation for Three Different Soils in Their Gypsum Content and Treated with Polymer and Peatmoss
Authors: Th Al-Asafi Raghed B , Al-Hadeethi Isam K
Published: August 2023

An experiment was conducted to compare the unsaturated hydraulic conductivity (K) calculated by Jackson equation and van Genuchten equation for soils different in gypsum content and treated with some soil conditioners. Two soils were used, gypsiferous soil (410 gm kg-1gypsium) and clayey soil (435 gm kg-1 clay), were mixed in three levels 0, 50, and 100%. The soils were treated with peat moss 0 and1%, polymer,0,1.and 2% and without addition. Then, were packed into plastic tubes 5 cm diameter and 25 cm in height at bulk density of 1.3 Mg m-3 and were exposed to three wetting / drying cycles. The unsaturated hydraulic conductivity was calculated from (Jackson equation, and van Genuchten equation. the results showed good agreement between K values measu dy using Jackson and van Genuchten equation using RETC program. The relationship between K and θ and percentages of gypsum is a positive and between K and ψ an inverse relationship. The value of K increased from 81.7 cm. day-1 to 137.8 cm. day-1 when the percentage of gypsum was increased from 46 to 410 g kg-1 consecutively for soil in treated with conditioners and within minor tension limits approaching zero. The K values decreased when the soil was treated with peatmoss and polymer, and the most effective treatment in reducing the K values was a mixture of (2% polymer + 1% peatmoss). The K values remained close to zero with medium to high tensions and also with medium to low θ, and it did not increase to an effective degree except when θ approached its upper limits and with low tensions, and its increase was exponential within these ranges.
Use of Epiphytic Diatoms in Cyperus Papyrus L. As Bioindicators in the Assessment of the Health of the Upper Euphrates River Between the Haditha Dam and Al-Baghdadi, Iraq
Authors: Al Tamaki Abdul Nasir A , Al Obeidi Nawras A
Published: August 2023

The aim of this study is to use epiphytic diatoms in Cyperus papyrus L. plant as biological indicators for estimating the water quality of the upper Euphrates River between Haditha Dam and Al-Baghdadi. Biodiversity and biological indicators for water quality estimation, along with the Canadian Water Quality Index. The study showed that the water of the upper Euphrates River is warm, light alkaline, the electrical conductivity and the total dissolved soled of water affected by agricultural land water and human activities, turbidity, total hardness and the biological oxygen demand, chloride and sodium did not exceed the permissible limits, while the values of calcium, nitrate and phosphate exceeded the permissible limits. And that the calcium values have exceeded the magnesium values, and that the water in the river is well ventilated. We have identified 130 species of epiphytic diatoms in Cyperus papyrus L. plant, including 6 species (5%) belonging to the centrales diatoms and 124 species (95%) belonging to the pennales diatoms, and the highest total number of cells of the epiphytic diatoms was recorded as 1322.3 cells x 103 / gm in site I. The values of physical and chemical factors, ecological indices, and water quality index agreed that the water of the upper Euphrates River is of moderate pollution, medium biodiversity, mesotrophic, and homogeneous in the presence of species.
Drought Assessment Using Two-Variate Modelling
Authors: Hasan Ihsan F , Kamal Nurul Hana M , Awchi Taymoor A , Abdullah Rozi
Published: August 2023

Drought is a natural hazard that mainly threatens water resources and food security. Due to climate change, an increase in drought events that may adversely affect various sectors is expected. Therefore, a reliable analysis of drought events is important. However, there is a deficiency in research works which deals with two-variate drought assessment and monitoring. This paper focused on drought assessment based on modelling the effective precipitation and runoff variables simultaneously. Drought indices are widely utilized to assess droughts in many regions around the world. The copula method was used to modelling a two-variate drought index based on the effective precipitation and runoff variables in northern Iraq as a case study. It was found that Frank is the optimal copula function to model the joint cumulative distribution function of effective precipitation and runoff. To assess the performance of the proposed two-variate index, it was compared with the widely used standardized precipitation index SPI and Standardized Runoff Index SRI. Where the Pearson correlation coefficients between 2-variate index and SPI, SRI were 0.78 and 86, respectively, for 3-month time scale, and were 0.83 and 82, respectively, for 6-month time scale. The results revealed that the proposed index is applicable and can comprehensively and effectively characterize drought events.
Effect of Application Different Combinations of Phosphogypsum and Humic Acids Mixed With Saline Irrigation Water on Broccoli Yield and NPK Concentration
Authors: Al-Falahi Muneer N , Al-Esawi Jabbar S , Salih Salih M , Mansoor Saif S , Jweer Khamees A
Published: August 2023

Long-term irrigation with saline water causes detrimental effects on the soil-crop system. The study aimed to determine the best combination of Phosphogypsum and humic acid can mitigate the negative effects of saline water irrigation on broccoli growth. Therefore, two-factorial field experiment was conducted according to a randomized complete block design with three replications during autumn season of 2021 in Fallujah district /Anbar governorate in sandy loam soil. The first factor included three levels of saline water irrigation, namely 2.5, 5.0 and 7.0 dS.m-1. while the second factor involved three levels of humic acids i.e., 0.0, 0.25 and 0.50 g/l mixed with three levels of phosphogypsum that is 0.0, 0.25 and 0.50 g/l. Fruits weight, height, yield, plant nitrogen content, plant phosphorus, and plant potassium content were measured. The results showed that the combinations under study ( humic acids and phosphogypsum) had a crucial role in reducing the negative effects of irrigation salinity. Moreover, the macronutrients availability increased with increasing humic acids concentration in irrigation water. The observed results show a significant increase in the weight of broccoli fruit and yield at T8 by giving 325 g. plant-1and 8.66 t.h-1 respectively under effect of the combination under study. Also, the studied combinations led to increase the N,P,and K concentration in plant tissues. Where the highest observed averages of nitrogen and potassium were 3.96% and 2.56% at T8 treatment. While The highest concentration of phosphorus was observed at treatment T9 reached 0.47%.
Evaluation the Suitability of Irrigation Water in Karma Island for Agriculture
Authors: Al-Bayati Ali H , Al-Azawi Hayder H , Al-Rawi Muthana K
Published: August 2023

To evaluating the suitability of surface and groundwater which used in agriculture in Karma Island in Anbar Governorate, eight wells depending on the topographical variation in the area as well as the surface water (Euphrates River) were selected. The water samples were collected during the winter and summer seasons at period 2021-2022. The tests included some chemical measurements of the water, its classification, and assessment of its suitability for agricultural purposes and its quality according to the Baber classification. The results showed significant difference between water sources and date of sampling in terms of studied indicators, the rates of the electrical conductivity ranged between 1.20-12.05 dSm-1 and the values of the degree of reaction in general was tend towards equality (6.9-7.3). The reason of spatial and temporal variation in this chemical water indicators refer to the geological rocks from which these ground waters pass through. As for salinity is concerned, the water of all wells was within the sever category, which indicated the magnitude of the use of this water in agriculture, because its proportion exceeds the limits of this chemical characteristic, while the surface resources water was within light to moderate category. In terms of the degree of reaction do not exceed the recommended index in the manual. As for its content of calcium, sodium, chloride and sulfate, all wells water was outside the usual range category, magnesium concentrations was within the permissible limit, while bicarbonate was within the slight to moderate category. The permeability index showed no objection to the use of this water for agriculture. Classified, all waters was in terms of salinity within class C4, as for the sodium hazards, the sources of water used for irrigation in sites W1, W2, W3, W4, and W5 were of low class S1, while wells W6, W7, W8 and W9 were within class. S2. According to geochemical properties and on basis of Cations, it became clear that there is water sovereignty Na+ and Ca+2, while according to anions, it was chloride-sulfur water.
The Effect of Salicylic Acid on the Growth Features of Sunflower Crops in Iraqi Middle-area Conditions
Authors: Rawi Abdulnaser T AL , Abdel Ghani Emad T
Published: August 2023

In order to determine the role of adding salicylic acid in reducing the impact of drought on the sunflower crop and increasing its tolerance to water stress, a field experiment was conducted during the spring of 2020 AD in one of the private agricultural fields in Latifiya district, Baghdad. Two agents were used in the experiment; the first was salicylic acid, which contained four Concentrations are (0, 100, 200, and 300 mg. L−1), and their corresponding symbols are S0, S1, S2, and S3, respectively. The second element is irrigation, which has three intervals (7, 14, and 21 days) between irrigations, and corresponding symbols I1, I2, and I3, respectively. The results indicated that, the highest plant height (PLH) was at 300 mg. L−1 treatment which was 189.98 cm. there are significant differences in the average number of leaves in the plant (NOL) when increasing the concentration of the spray solution of salicylic acid on the sun flower plant, as the highest average trait was 29.98 leaves. Plant−1 at the treatment 300 mg. L−1. The highest average LA was at the treatment 300 mg.-1 which amounted to 1931.9 cm2.Plant-1.the treatment 300 mg. L−1 recorded the highest average for leaf area index (LAI) was 4.95. The irrigation intervals have shown a clear significant effect on all growth characters, the irrigation interval at 7 days gave highest rate of plant height (189.05 cm), number of leaves in the plant (NOL) (29.05leaf. Plant−1), Leaf area of the plant (LA) (1711. 2cm2.plant−1), Leaf area index (LAI) (4.83).
Effect of Super Absorbent Polymer and Ceratophyllum Powder Application on Some Soil Physical Properties
Authors: Salih Salih M , Al abaied Abdalwhhab I
Published: August 2023

A two factorial laboratory experiment was conducted according to randomized complete block design with three replications, to investigate the effect of super absorbent polymer (SAP) and ceratophyllum powder application on some physical characteristics of loamy sand soil. The first factor included three levels of super absorbent polymer, namely 0,0.2, and 0.4 %. While the second factor consists of three levels of ceratophyllum powder i.e., 0,2, and 4 %. The treated soil (treated with super absorbent polymer and ceratophyllum powder) was exposed to 14 cycles of wetting and drying. Effect of experiments factors on coefficient of linear extensibility, soil bulk density and total porosity were measured. The obtained results show that the super absorbent polymer and ceratophyllum powder application led to increase the dry soil bulk density, total porosity, and the coefficient of linear extensibility values for all application levels. Regarding the soil aggregate stability, a significant increase was observed under effect of super absorbent polymer and ceratophyllum powder application. Where the highest value of soil aggregate stability was recorded at 0.4% level of SAP reached 54.2%. Likewise, the highest value of soil aggregate stability under effect of ceratophyllum powder application reached 30.7% at 4% level of application, compare to the control treatment that gave 11.1 % with increasing rate reached 76.5%. In same direction, all moisture content had increased under effect of study factors. However, the super absorbent polymer was superior to ceratophyllum powder application.
Vertical and Lateral Variation of Ecological Risk Index of Heavy Metals in the Euphrates River Sediments between Heet and Fallujah, Iraq.
Authors: Saber Mohammed , Saod Wahran M , Al-Heety Emad A
Published: August 2023

The heavy metals (HMs) contamination of river sediments and their ecological risks is a global environmental problem that has attracted the attention of researchers and those interested in environmental protection. The study aims to investigate the ecological hazards of some HMs in sediments of Euphrates River between the cities of Heet and Fallujah, Iraq and their lateral and vertical variations. At three depths—0-30, 30-60, and 60-90 cm—samples of sediment were collected from five sites. Atomic Absorption Flame Emission Spectrophotometer (ASC.7000) was used to measure concentration of Cd, Cr, Cu, Ni, Pb, and Zn. The ecological risk index (ErI) values of metals in Euphrates River sediment in the study area take the following descending order: Cd > Ni > Cu > Cr > Pb > Zn. The ErI levels were low for Cr, Cu, Ni, Pb and Zn and considerable ecological risk for Cd. The obtained results did not show a common lateral variation pattern of the ecological risk of the measured metals. There is a high level of risk for the measured metals at the downstream sampling sites except for the risk from Cd on the contrary. The potential ecological risk of Cd, Cr, Pb and Zn showed a similar vertical variation pattern which in turn reflects a common source or origin for these metals, while copper and nickel showed a different common distribution pattern.
Hydrogeochemical Evaluation of Surface and Groundwater in Haditha Area, Al-Anbar Governorate, Western Iraq
Authors: Al-Hadithy Israa B , Al-Mallah Aahed Y
Published: August 2023

This research deals with the study of the hydrochemical characteristics of surface water and groundwater to assess the quality of water and its suitability for different uses in the Haditha region. Thirty –Two samples were collected in July 2022,6 samples were taken from the Euphrates River and 17 samples from wells were analyzed. In this study, main cations ( Ca2+, Mg2+, Na+, and K+) and anions (Cl-, SO4, HCO3),Total dissolved Solids(TDS), pH, Electrical conductivity(EC), and Temperature(T) were studied. The results show that the water types are mainly earth-alkaline water with an increased portion of alkalis with prevailing SO4 and Cl according to Piper and Stiff diagram. The results of the water quality index (WQI) show that surface water are suitable for drinking while the groundwater is not suitable except for W1, W13, W15, W16 and W17. The classification of water for irrigation purposes according to the Sodium Adsorption Ratio and Residual sodium carbonate showed that the ground and surface water in this region is excellent and good quality according to Permeability Index. Irrigation water quality based on sodium ion percentage indicates that all samples belong to the permissible category for groundwater except for W1, W11, and W16, while Surface water is good quality for irrigation. Finally, the absence of management and low discharge, are the primary reasons for the continuous deterioration of water quality.
Numerical studies on tugboat performance during pushing operations
Authors: Abdelghafor Z , Taimuri G , Kujala P , Wang Y , Hirdaris S
Published: August 2023

This paper introduces a RANS CFD methodology for the evaluation of tugboat dynamics during pushing operations. Two- and three- dimensional methods that respectively utilize “Dynamic Fluid Body Interactions - (DFBI)” and “Tug Force Equilibrium kinematics-(TFE)” are assessed and compared with the aim to better understand the influence of fluid modelling on ship dynamics. For the DFBI method, an unsteady RANS solver comprising of a dynamic fluid body interaction module and a contact mechanics coupling algorithm are used to predict the forces between a tugboat and an assisted ship. For the TFE method, a steady RANS method is applied and contact actions are calculated as a sum of the hydrodynamic forces on the hull and the propeller. Whereas DFBI accounts for the time variation of the contact forces, the TFE is more rapid and could be used to derive operational decision support criteria. To demonstrate the latter the TFE method is used to derive the pushing forces based on a set of 16 numerical simulations. It is concluded that irrespective of the model used the tugboat speed and orientation may amplify the pushing forces. This effect could be prominent, especially at slow speeds for which the sway force acts in opposite direction to the tug.
A deep learning method for the prediction of focused waves in a wave flume
Authors: Zhang Mingyang , Tavakoli Sasan , Hirdaris Spyros
Published: August 2023

Rogue waves pose a significant risk to marine safety, emphasizing the need to accurately predict their occurrence in the open ocean. However, the complexity of their evolution, which may involve nonlinear physical phenomena such as wave-wave interaction and modulation instability, makes this task challenging. Currently the reconstruction of rogue waves involves generating focused waves through the superposition of different spectral components of irregular waves that are in phase at the focusing point. Despite its effectiveness, this approach is limited. The paper introduces a deep learning method based on Long short-term memory (LSTM) to predict focused waves generated in a Computational Fluid Dynamics (CFD) flume in the time domain. The model is trained on 60% of the generated wave time series, with the remaining 40% used for both validation and testing. The results demonstrate that the proposed method can assist with the prediction of focused waves at various observation points, indicating its potential as a promising approach for predicting rogue wave behaviour in the ocean.
A two-way coupled FSI ship hard grounding dynamics model
Authors: Taimuri G , Mikkola T , Kujala P , Hirdaris S
Published: August 2023

In the maritime sector, ship grounding incidents continue to be a serious problem that may lead to oil spills, capsizing, severe property damage, and even fatalities. Grounding accidents are currently understood utilizing inadequate statistical datasets, probabilistic grounding scenarios, and deterministic computational crashworthiness methodologies due to a lack of practical tools and techniques. The implementation of multiphysics assessment techniques is essential for the development of improved ship safety standards. This involves the use of rapid models for structural integrity rules and damage stability regulations. Taimuri et al., (2022) [1] introduced a rapid two-way coupled fluid-structure interaction (FSI) model that seeks to efficiently examine accidental loads following a ship hard grounding event to fulfil such a requirement. The current study offers an overview of the algorithm and its limitations.
Asymmetry in sagging and hogging responses of a ship hull
Authors: Matusiak J , Karola A , Niemelä A , Mikkola T , Hirdaris S
Published: August 2023

In this paper asymmetry in sagging and hogging of a hull progressing in regular waves is investigated by applying a weakly nonlinear potential flow theory. At first instance ship motions in waves are evaluated using a linear strip-theory yielding transfer functions of ship motions and sectional loads. Then, by assuming time-histories of ship motions the nonlinear part of the Froude-Krylov and restoring forces and moments are evaluated using a panel representation. Linear and weakly nonlinear predictions are compared against available model tests for a roll-on/off (Ro-Pax) ship hull. The results confirm that importance of nonlinearities of restoring and Froude-Krylov part of wave loading on asymmetry of sagging and hogging.
Comparative summary of approaches used with the impulse response method
Authors: Wermbter M. , Altenbach L. , Detlefsen O. , Abdel-Maksoud M.
Published: August 2023

This paper presents a comparison of various methodologies to calculate the seakeeping behaviour of ships using the impulse response method. Developments of several authors incorporate non-linearities regarding the radiation, diffraction and wave forces. In contrast to frequency domain methods, advantages are expected if ship motions become non-linear, for example in waves with high steepness ratios. The comparison is structured into analysis for each force component with and without motions in waves. The main contribution is the quantitative analysis for several ships, forward speeds and methodologies. Multiple frequency domain methods are incorporated in the analysis. The focus of the analysis lies on the evaluation of applicability as well as the limits of the method for all states investigated. The results of the impulse response method show the following: The method is applicable to several forward speeds. In long waves, the choice of the parameters calculated in the frequency domain for the computation of the radiation and diffraction forces has a strong influence on the computed motion amplitudes. In short waves, the computation of the added resistance is a considerable challenge. Especially at high forward speeds, the consideration of the stationary wave system is essential for obtaining accurate results with three-dimensional panel codes.
Numerical study on the influence of nozzle divergence half angle on thrust oscillation characteristic of underwater jet power
Authors: Si Pengfei , Wang Ningfei , Xia Shitong , Shi Lin , Li Shipeng , Tang Jianing
Published: August 2023

Underwater rocket propulsion is increasingly used in advanced marine vehicles that may be subject to supersonic gaseous jets while submerged. This work investigates the influence of supersonic nozzle divergence on the multi-flow field evolution process and the thrust oscillation characteristics by multiple numerical simulations using a VOF multiphase flow model. Four nozzle divergence half angles are taken into consideration. The analysis indicates that the thrust rises sharply at nozzle closure opens, then rapidly decreases and follows another rise. The thrust oscillates at high frequencies. As a result, increase of the nozzle divergence half angle leads to the size decrease of flow bubbles but does not affect the changing trends of the thrust. Increase of the nozzle divergence half angle leads to a reduction of the frequency of the thrust oscillations.
Numerical study of second-order wave forces using a Rankine panel method
Authors: Dong Guohua , Huang Jianghao , Yao Chaobang , Feng Dakui , Meng Fanliang
Published: August 2023

Numerical analysis of the wave forces acting on ships can be complex primarily because of the interactions between incident waves and structures. In this paper, the three-dimensional frequency domain Rankine panel method is used to study the seakeeping and second-order wave drift forces of a ship in waves. The model considers second-order wave forces acting on the ship hull and therefore accounts for slow drift ship motions and the added resistance. The second-order wave forces are evaluated using the pressure integral method, also known as the near-field approach. The unsteady velocity potential is divided into three parts namely (a) incident, (b) diffraction and (c) radiation to satisfy the Laplace equation. To avoid wave reflection the Rayleigh’s artificial friction is used in way of the free surface boundary. This method is equivalent to introducing a numerical damping beach for energy dissipation. The numerical results are compared with those of experiments for Wigley-III hull in head waves and the SCb-84 hull in oblique waves. Good agreement is obtained.
Hydrodynamic performance of manta rays under different motion parameter
Authors: Gao Pengcheng , Huang Qiaogao , Pan Guang , Liu Jing , Shi Yao , He Xing , Tian Xushun
Published: August 2023

This paper presents a numerical simulation of the steady propulsion state of manta rays and investigates the influence of single motion parameters and the addition of perturbation signals on the hydrodynamic characteristics and vortex evolution of manta rays. A numerical model and the motion equations of the manta ray were established by observing the living organisms, and then a computational method combining the immersed boundary method (IBM) and the Sphere function-based Gas Kinetic Scheme (SGKS) was used to simulate the active propulsion state of the manta ray. The results show that in a single motion parameter, as the motion frequency increases, the thrust force increases subsequently, but the propulsion efficiency decreases; with the increase of motion amplitude, the thrust also increases, and the propulsion efficiency reaches the maximum at the dimensionless amplitude of 0.35; as the wavenumber increases, the thrust reaches its maximum at wavenumber of 0.4, and the propulsion efficiency increases subsequently. When the same amplitude low-frequency sinusoidal perturbation is added, both thrust and efficiency decrease when the perturbation frequency is less than or equal to 0.4, and increase when the perturbation frequency is greater than 0.6. This work provides a new perspective to study the influence of manta ray motion parameters and perturbation parameters on its hydrodynamic characteristics.
Numerical Investigation on Drag and Vortex Induced Vibration Characteristics of Multiple Cylinders
Authors: Araki M
Published: August 2023

The drag and vortex induced vibration (VIV) characteristics of a multiple cylinder are investigated using the detached eddy simulations. The multiple cylinders consist of a single main cylinder and twin auxiliary cylinders for a deep sea mining riser. Tandem and side-by-side arrangements are tested and compared with the single cylinder. The drag characteristics are investigated with the stationary case in the range of 0.5∼2.0 × 105 in Reynolds number (Re). The drag of the tandem arrangement shows smaller drag than those of the single cylinder while it’s consisted with the three cylinders. The stationary vortexes are observed at the clearance between the main and auxiliary cylinder which make the tandem arrangement become airfoil-like section as a total which induce the smallest drag than the other cases. The VIV characteristics are studied with the cases of forced oscillation in the cross-flow direction. The damping and added mass coefficients in cross-flow direction are estimated from the time series of the lift forces. Flow field analysis reveal the difference in VIV characteristics due to the variety of the arrangements and the single pipe.
Uncertainty Quantification of Turbulence Model Applied to a Cavitating Hydrofoil
Authors: Romani Simone , Morgut Mitja , Parussini Lucia
Published: August 2023

This paper presents the Global Sensitivity Analysis of the coefficients of the standard k-ε turbulence model used in RANS (Reynolds Averaged Navier-Stokes) simulations aimed to predict the flow around a bi-dimensional hydrofoil operating at non-cavitating and cavitating flow regimes. The sensitivity analysis is treated by the Sobol Decomposition, where the Sobol Indices are computed through the Polynomial Chaos Expansion of the 2-nd order with a Point-Collocation Non-Intrusive approach. From the current results, it seems that the considered cavitating flow regime is less sensitive to the variability of the input parameters, at least for the prediction of lift and drag.
Developing methods of decomposing the physical resistance components acting on a hydrofoil
Authors: Chernyshev Lev , Kabaliuk Natalia , Jermy Mark , Corkery Simon , Bernasconi Daniel
Published: August 2023

The America’s Cup is a sailing competition contested by teams fielding bespoke yachts designed and built to the AC75 class regulations. These yachts make use of hydrofoils, which permit them to lift their hulls above the water surface. When in this “foiling” regime, the drag forces on the hull are drastically lower, permitting greater sailing speed. Predicting hydrodynamic forces produced from hydrofoils on race yachts remains challenging, due to a wide operating regime and complex hydrodynamical phenomena. In this study, existing wake survey methods of decomposing the total drag force of a hydrofoil into physical subcomponents were developed through examining their sensitivities and accuracy. Computational fluid dynamics (CFD) simulations of a rectangular NACA4412 hydrofoil were performed to generate data for the wake surveys. The hydrofoil was simulated at a submergence depth of one chord. Viscous flow was simulated with the k–ω SST turbulence model in steady state; and the volume-of-fluid (VOF) model was used to capture free surface effects. Chord Froude numbers of 0.5, 1, 2 and 4 were investigated, corresponding to Reynolds numbers of 2.57 × 105, 5.15 × 105, 1.03 × 106 and 2.06 × 106. Force decomposition was performed using two different wake survey methods – one each for the wave and viscous drag – as well as Trefftz plane analysis for the induced drag. Wave drag forces could be reliably isolated at all tested Froude numbers, while reliable predictions of the viscous drag were dependent on the Froude number and method of isolating the hydrofoil’s viscous wake region. Accurately isolating the induced drag component proved challenging due to free surface interactions. Careful selection of the wake survey location was also necessary for accurate predictions of any of the drag components.
Drag reduction and power optimization due to an innovative, toroidal hull form of an AUV
Authors: Miller Lakshmi Madhavan , Njaka Taylor , Brizzolara Stefano , Curtin Thomas
Published: August 2023

The use of unconventional design has become a norm for mission-specific underwater autonomous craft. Geometrical characteristics and drag optimized shapes of single-hulled underwater vehicles are known since 1970s and a few significant improvements have been possible since then. These are mostly related to the efficiency of a wake adapted propeller, positioned at the stern in wake of the hull. In a novel effort, when the propeller is integrated into the craft at center-line, and the hull in its entirety is designed to act as the duct, the drag of the hull is further reduced. This craft uses a toroidal hull form that distributes payload axi-symmetrically around an internal ducted thruster. The craft is designed to operate at an economic cruise speed of 2kn. The power consumption is optimized to achieve an endurance of over 500 miles through this implementation of a ducted thruster. The hydrodynamic characteristics of the new toroidal hull are compared to those of a reference design which is slender and conventionally shaped. This conventional design is intended for the same volume and dimensions of payload. A reduction of 13% in drag from the first to final design iteration is achieved. This reduction in drag is due to a higheer effective length to thickness ratio of the ducted AUV, quantified in terms of a new parameter defined as Ih
. The reduction of the wetted surface area also contributes to the drag optimization. The article shows that the shape of the leading edge of the toroidal hull becomes important to achieve low drag. The process of design and optimization using CFD, with the most appropriate turbulence models is detailed. The beneficial effect of the acceleration induced in the flow at the leading edge and trailing edge of the hull by the integrated thruster is studied and explained with the help of CFD results.
Cavitation of some copper alloys for naval propellers: electrolyte effect
Authors: Biezma Moraleda M V , Merino Galván L , Linhardt P
Published: August 2023

Efficient shipping is becoming more challenging, not only because of the increasing demand for this means of transport, the performance requirements and the optimisation of resources, but also because of the environmental constraints. Cavitation is a harmful phenomenon that can affect different systems of a ship such as pumps, valves, impellers, pipes, etc., but is particularly known for its effect on propellers, associated with loss of power and even impairment of structural integrity. The mechanical effect of cavitation on metallic materials is in general superimposed by corrosion and may thus lead to a synergistic degradation phenomenon. In this work, the cavitation behaviour and the potential synergistic effect with corrosion was evaluated for three widely used copper-based alloys, NAB (Nickel Aluminium Bronze), MAB (Manganese Aluminium Bronze), and a brass (low lead content) using three types of water: natural seawater, synthetic seawater and synthetic brackish water. Experiments were carried out in an ultrasonic bath, followed by structural surface characterisation. The main result is that MAB is most susceptible to both, general surface damage and deep localized attack. This is attributed to its poor ability in regenerating the protective layer, the area ratio of their phases and the high hardness of the κ-phase, in combination with high mechanical stresses during impacts affecting the grain boundaries. Moreover, natural seawater was found to increase cavitation, attributable to the dispersion of micro-particles, while brackish water with its content of sulfidic species was found to promote the strongest synergy between corrosion and cavitation.
Regional polar warming linked to poleward moisture transport variability
Authors: Bintanja Richard , Graversen Rune Grand , Kolbe Marlen
Published: August 2023

Polar warming, ice melt and strong precipitation events are strongly affected by episodic poleward advection of warm and moist air (Woods and Caballero 2016 J. Clim.
29 4473–85; Wille et al 2019 Nat. Geosci.
12 911–6), which, in turn, is linked to variability in poleward moisture transport (PMT) (Nash et al 2018 J. Geophys. Res. Atmos.
123 6804–21). However, processes governing regional impacts of PMT as well as long-term trends remain largely unknown. Here we use an ensemble of state-of-the-art global climate models in standardized scenario simulations (1850–2100) to show that both the Arctic and the Antarctic exhibit distinct geographical patterns of PMT-related warming. Specifically, years with high PMT experience considerable warming over subarctic Eurasia and West-Antarctica (Raphael et al 2016 Bull. Am. Meteorol. Soc.
97 111–21), whereas precipitation is distributed more evenly over the polar regions. The warming patterns indicate preferred routes of atmospheric rivers (Woods and Caballero 2016 J. Clim.
29 4473–85), which may regionally enhance atmospheric moisture content, cloud cover, and downward longwave radiative heating in years with comparatively high PMT (Scott et al 2019 J. Clim.
32 665–84). Trend-analyses reveal that the link between PMT-variability and regional precipitation patterns will weaken in both polar regions. Even though uncertainties associated with intermodel differences are considerable, the advection of warm and moist air associated with PMT-variability is likely to increasingly cause mild conditions in both polar regions, which in the Arctic will reinforce sea-ice melt. Similarly, the results suggest that warm years in West-Antarctica disproportionally contribute to ice sheet melt (Trusel et al 2015 Nat. Geosci.
8 927–32), enhancing the risk of ice-sheet instabilities causing accelerated and sudden sea-level rise.
Unequal carbon tax impacts on 38 million German households: assessing spatial and socio-economic hotspots
Authors: Többen Johannes , Pichler Peter-Paul , Jaccard Ingram S , Kratena Kurt , Moran Daniel , Zheng Heran , Weisz Helga
Published: August 2023

Carbon pricing is a core climate policy in many countries. However, the distribution of impacts is highly unequal across income brackets, but also across household types and regions. The complex interplay between household characteristics and location specific factors such as building stock and transport infrastructure considerably hampers our understanding of the inequality impacts of carbon taxes and the development of remedial measures. In this paper, we simulate the impacts of carbon taxes and compensation on the purchasing power of more than 38 million German households living in over 11 000 municipalities. We find that the strength of impacts varies more within income groups (horizontal inequality) than across income groups (vertical inequality), based on demographic, socio-economic and geographic factors. Without compensation, a carbon tax of €50 per ton doubles the number of households at risk of becoming energy poor, the majority of them low-income families in remotely located small and medium cities. A lump sum payment of €100 per capita and year reduces inequality impacts and additional energy poverty risk substantially.