bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detached Eddy Simulation of the 28° Ahmed Body at a Low Reynolds Number
Authors: Siddiqui Naseeb Ahmed , Agelin-Chaab Martin 
Published: September 2022

Abstract
Studies on the Ahmed body with varying slant angles remain an interesting topic, especially analyses of the flow structures and the corresponding changes in aerodynamic drag and lift in the region 25° ≤ α ≤ 30°, which are not fully understood. Physical insights in the aerodynamic performance of a simplified geometry such as the Ahmed body can improve the geometric optimization of road vehicles for fuel economy improvement. Therefore, this paper examines the three-dimensional wake dynamics of a 28° slanted Ahmed body and proposes a flow control method for its drag reduction. This slanted angle is rarely reported in the open literature. The study is conducted by applying the improved delayed detached eddy simulation (IDDES) using the SST k-ω turbulence model to solve the Navier-Stokes equations at a low Reynolds number of 1.4 × 104 based on the model height. The results reveal a flow separation at the slant surface and reattachment at the rear leading to a secondary separation. A small reverse flow develops after the first separation over the slant surface. Similarly, another minor reverse flow region is concentrated in the middle of the vertical base. However, the flow control method modifies the flow structures similar to the low-drag regime Ahmed body. The aspect ratio of the recirculation region is increased, and the reattachment at the rear end vanishes. Consequently, even at the low Reynolds number studied here, the drag is reduced by up 11%. In addition, the study employs both the time-averaged and time-resolved turbulence statistics and vortex identification methods to provide physical insights into flow modifications and drag reduction. Hence, the paper provides additional valuable information on the flow structure at low Reynolds number to the body of knowledge.
Computational Modeling and Hydrodynamic Analysis of Fish Schools in Three-Dimensional Arrangements
Authors: Pan Yu , Zhang Wei , Dong Haibo 
Published: September 2022

Abstract
In this work, numerical simulations are employed to study hydrodynamic interactions in trout-like three-dimensional (3D) fish bodies arranged in vertical and horizontal planes. The fish body is modeled on a juvenile rainbow trout (Oncorhynchus mykiss) and is imposed on a traveling wave to mimic trout swimming. Three typical minimal schools are studied, including the in-line, the side-by-side, and the vertical school. A sharp interface immersed-boundary-based incompressible Navier-Strokes flow solver is then used to quantitively simulate the resulting flow and hydrodynamic performance of the schools. The results show that the hydrodynamic efficiency of the leading fish in the in-line school increases by 5.28%, and the thrust production and efficiency of the side-by-side school are enhanced by 2.28% and 3.86%, respectively. Besides, the thrust production of the vertical school increases by 21.6%. The results suggest great potential in exploiting the hydrodynamic benefits in fish schools arranged in three-dimensional space.
Concentrating Slurries Mesofluidically for Nuclear Waste Processing
Authors: Pease Leonard F. , Bamberger Judith Ann , Burns Carolyn A. , Minette Michael J. 
Published: September 2022

Abstract
High-level radioactive waste stored at the Hanford Site near Richland Washington will be retrieved, transported, treated, and concentrated prior to final vitrification. This waste, stored in million-gallon underground tanks, is to be retrieved and transported via pipeline to the treatment facilities at low solids loading. Concentration is a necessary step to remove transport fluid and supernatant liquid. Several techniques are available to concentrate slurries including settle/decant, filtration, and evaporation that all present unique challenges. Using evaporators to dewater sludge is time consuming and energy intensive; settle-decant is time consuming and requires use of large settling vessels; filtration is prone to clogging and caking. Improvements in slurry concentration capabilities are desirable to help minimize waste treatment costs.
Here we investigate mesofluidic separation to concentrate slurries. This mesofluidic system uses a high void space, low pressure drop grid installed within an existing pipe spoolpiece. The grid spacing is configured to force solids to migrate to one side of the grid and fluid to migrate to the other side of the grid as the slurry flows within the pipe. The fluid component exits the process stream through a branch and can be reused for additional slurry retrieval and transport. The higher concentration slurry component remaining in the “express lane” then flows through a second “grid” to be further concentrated. Several grid inserts in series may be used to obtain the degree of solids separation required to support downstream processes. The concentrated slurry then becomes the process feed for vitrification.
A series of experiments were conducted to evaluate the ability of the mesofluidic grid installed within the spoolpiece to concentrate particles within a size range of interest for radioactive fluid processing. Experiments evaluated the potential to operate units in series in two configurations: further concentrating slurry routed from the express lane and further solids removal of fluid routed from the permeate line. Both configurations yielded enhanced results: additional concentration or additional dilution. Test results are presented and applicability to process enhancements is described.
Sand Erosion Measurements and Simulations Under Churn Flow Conditions in Elbows in Series
Authors: Rajkumar Yeshwanth Raj , Karimi Soroor , Shirazi Siamack A. 
Published: September 2022

Abstract
Pipeline geometries such as elbows, tees, chokes cause a rapid change in the flow direction. Therefore, they are more prone to solid particle erosion when silica particles are entrained with oil and gas production. Consequently, studying the erosion pattern and magnitude for elbows in series in liquid-gas-solid flows is vital. The current work measured erosion data using an ultrasonic transducer (UT) in 76.2 mm inner diameter stainless steel elbows. The second elbow is separated at three diameters from the first elbow. Experiments were conducted with water, air, and 300 μm sand particles at a mixture velocity of 11.4 m/s. Experimental data was collected for two different superficial velocities by keeping the mixture velocity constant. The erosion magnitude and hotspot location change significantly as the gas velocity increases. Moreover, CFD simulations were performed using the Eulerian multiphase model and Reynolds Stress Model (RSM) for liquid-gas-sand flows to predict erosion patterns and magnitude.
On to Quantifying the Effect of Droplet Size Distribution on the Airborne Transmission of the Virus
Authors: Shrestha Rajendra , Delgado Juanpablo , Fontes Douglas , Stiehl Bernhard , Reyes Jonathan , Schroeder Steven , Ahmed Kareem , Kinzel Michael 
Published: September 2022

Abstract
This research will study a novel aspect of the physics of COVID-19 transmission associated with actively altering droplet size distribution. Viruses can be transmitted through droplets and aerosols released during speaking, sneezing, and coughing phenomena. We previously found that these distributions can be altered using food ingredients. The study will be carried out to study the hypothesis of relaxed guidance in social distancing and mask usage is possible with the proposed approach using CFD models of human sneezes. The adult human is positioned inside a ventilated room condition and the droplet/aerosols are to be released to explore the impacts of the various distributions that relate to how the food ingredients vary the function, hence, the size of the droplets will be the function of the use of food ingredients. Results study the concentration of droplet particles at various distances away from the mouth, also called exposure maps and indicate that Corn Starch and Xanthum usage increase the exposure intensity level, while Xanthum reducing the exposure area implies that social distancing can be reduced with its use. In contrast, the use of Lozenge and Zingiber reduces the exposure level, related to the increase in the viscosity and reduction of the mass flow rate of saliva.
Interactions of Aerosol Droplets With Ventilated Airflows in the Context of Airborne Pathogen Transmission
Authors: Schroeder Steven , Stiehl Bernhard , Delgado Juanpablo , Shrestha Rajendra , Kinzel Michael , Ahmed Kareem 
Published: September 2022

Abstract
This multidisciplinary study provides a comprehensive visualization of airborne aerosols and droplets coming into contact with crossflows of moving air utilizing both experimental particle measuring methods and multiphase computational fluids dynamics (CFD). The aim of this research is to provide a Eulerian visualization of how these crossflows alter the position and density of an aerosol cloud, with the goal of applying this information to our understanding of social distancing ranges within outdoor settings and ventilated rooms. The results indicate that even minor perpendicular crossflows across the trajectory of an aerosol cloud can greatly reduce both the linear displacement and density of the cloud, with negligible increases in density along the flow path.
Robust Strain/Rotation-Rate Tensor Reconstruction Based on Least Squares RBF-QR for 3D Lagrangian Particle Tracking
Authors: Li Lanyu , Sakib Nazmus , Pan Zhao 
Published: September 2022

Abstract
Based on the least squares and Radial Basis Function (RBF), we propose to use a robust method to reconstruct the velocity gradient and strain/rotation-rate tensor from Lagrangian Particle Tracking (LPT) data. A stable RBF method, RBF-QR, is employed to provide robust approximation in the flat limit of shape functions without suffering ill-conditioning. Least squares method enables the reconstruction of noisy data and further improves the robustness of the calculation on realistic experimental data. The use of Partition-of-Unity Method (PUM) localizes the calculation and allows handling large data set in 2D and 3D and improves computational efficiency. The accuracy and robustness of the method is validated on both 2D and 3D simulated LPT data with artificial noise based on Direct Numerical Simulation (DNS). The technique is further tested on the 3D LPT data obtained from a synthetic jet experiment.
Numerical Analysis to Study the Effect of Control Temperature Location Inside a Datacenter
Authors: Hashmi Atta Ul Mannan , Tipu Arshan Ahmed , Butt Fahad Rafi , Akhtar Imran , Khalid Muhammad Saif Ullah 
Published: September 2022

Abstract
Modern HVAC control systems lack any sort of a link between the temperature sensors and thermal fields inside closed environments. Whether it is the CRAHBP or a single-unit HVAC system, temperature sensors are coupled with the return air temperature. This connection causes HVAC systems to continue operating until the return air temperature falls below a value defined by an operator. It results in wastage of electricity, because a significant amount of electricity is used to cool down almost the entire closed environment. With rapid advancements in cloud computing services, the expansion of existing and establishment of new datacenters is expected to grow. A major portion of the total electricity consumption in datacenters is consumed by the HVAC equipment. In this work, through high fidelity numerical simulations, we show that a coupling between HVAC sensors and the temperature field in regions of interest inside datacenters can lead to substantial saving of energy. For this study, we consider a tier-2, localized datacenter. It should be noted that the implementation of the proposed flow control method presented in this research work will result in improvement of the overall efficiency of the HVAC system without any major changes to already existing infrastructures of datacenters. Our CFD simulations predict that implementing the proposed control method reduces the power consumption of cooling equipment in the datacenter by 23%.
Are Active Fluids Age-Dependent?
Authors: Samadi Zahra , Mehdizadeh Allaf Malihe , Vourc'h Thomas , DeGroot Christopher T. , Peerhossaini Hassan 
Published: September 2022

Abstract
Active fluids are often is known as the aqueous suspensions of self-propelled elements such as bacteria, algae, or sperm cells, which their properties fundamentally differ from conventional fluids. Active fluids exhibit remarkable physical manifestations over a wide range of scales, from time-dependent microscopic diffusion to the large-scale colonization of aqueous spaces. Properties of active fluids depend on the behavior of microbial suspensions, among which motility plays a crucial role.
In this work, we focus on the effect of microbial growth and aging on microorganism motility. Hence, the motility behavior of cyanobacterium Synechocystis sp. CPCC 534, and its relationship with aging were investigated in a closed microfluidic chip. The growth of Synechocystis cultures was followed from the lag phase, through exponential and linear growth up to the stationary phase. Culture samples were periodically examined; cell populations were measured by spectroscopy technique and cell trajectories were tracked by video-microscopy. Cell trajectory length and average cell motility were extracted from the video recordings and were correlated with the age and growth phase of the bacterium.
Experimental Investigation of Hybrid Propulsion Mechanism for Robotic Fish
Authors: Aly Abdulrahman , Omari Mohamad , Ghommem Mehdi , Romdhane Lotfi 
Published: September 2022

Abstract
In this work, we investigate the performance of a hybrid propulsion mechanism for a robotic fish based on the combined bending and flapping motions of a flexible tail with a bio-inspired caudal fin extension. The tail consists of an Aluminum substrate attached to a pair of macro-fiber composite (MFC) piezoelectric laminates and subject to flapping motion actuated by a servomotor. A testing platform, equipped with a distance laser sensor, is developed to measure the produced tail deformation over a range of actuation frequencies and amplitudes of lateral oscillations. The objective is to verify the biomimicry of the system and identify the optimal actuation that maximizes the thrust generation of the propulsive tail. Optimal actuation entails the vibration of the MFC at resonance and utilizing its dynamic model to synchronize its motion with that of a motor to produce a biomimetic motion. Frequency response curves are generated and verified against a model of underwater beam dynamics. The experimental component of the present work also includes the development of a robotic fish prototype that encompasses a main 3d-printed body designed as a streamlined waterproof enclosure of the electronics including a microcontroller, a Raspberry Pi camera module, and a high-voltage amplifier along with a servomotor actuating the bio-inspired tail. The mass distribution of the electronic components is adjusted to ensure the buoyancy of the robotic fish in water. Free-swimming tests of the robot are successfully conducted to demonstrate the performance of the hybrid propulsion mechanism in terms of forward swimming speed and maneuverability. The performance is then compared against other robotic fish works and found to provide a higher propulsion compared to smart material-based designs while also providing a smaller design compared to the motor-based solutions.
Immersed Boundary Method Implemented in LES for Flow Past a Sphere at Subcritical Reynolds Numbers
Authors: Marefat H. Ali , Alam Jahrul , Pope Kevin 
Published: September 2022

Abstract
Flow within the sub-critical range of Reynolds number around spherical bluff bodies has a complex dynamic behaviour due to transient fluid flow happening in the wake of the sphere. Large-eddy simulation and penalization methods have been used successfully for approximating these flows for the last two decades. In this work, a combination of two approaches is presented for flow past a spherical bluff body at sub-critical Reynolds numbers. Results at Re = 1000 presented in comparison with direct numerical simulation results and experimental data available in the literature. They show a very good agreement with data in the literature despite using a comparably large computational mesh. In addition, the essential characteristics of flow dynamics and the coherent vortical structures in the wake of the sphere are investigated and discussed in detail for Reynolds numbers less than 10,000.
System Dynamics and Tomography-Based Control of a Gas-Liquid Inline Swirl Separator
Authors: Garcia Matheus M. , Portela Luis M. 
Published: September 2022

Abstract
Swirl-based separators are widely used in the separation of two-phase flows with phases of different densities, e.g. in the oil and gas industry. The separation is based on centrifugal forces associated with the swirl motion, that splits the original mixture into a light-phase core and a heavy-phase annulus, captured by two separate outlets equipped with control valves. Due to the complex (unsteady) dynamics of the flow and variations in the mixture that reaches the separator, real-time controllers are required to keep the separation optimal. Traditionally, the control is based on pressure measurements at the boundaries of the separator. However, pressure is only indirectly related to the separation. A more direct (and potentially more effective) control variable is the distribution of phases inside the separator, which can be monitored using soft-field tomography. This idea is explored in this work using an air-water inline-swirl separator facility equipped with an Electrical Resistance Tomography (ERT) sensor, that determines the size of the air core in real-time using a newly developed fast ERT reconstruction algorithm. The dynamics of the system was studied for different valve actions and summarized into a Transfer Function of the process, which is used to design a PI controller. The approach was successful and the control strategy implemented kept the air core near the setpoint in the presence of disturbances in the air flow rate reaching the separator.
Effect of Porosity on Tool Wear During Micromachining of Additive Manufactured Titanium Alloy
Authors: Varghese Vinay , Mujumdar Soham 
Published: September 2022

Abstract
Porosity is a major quality issue in additively manufactured (AM) materials due to improper selection of raw material or process parameters. While porosity is kept to a minimum for structural applications, parts with intentional (engineered) porosity find applications in prosthetics, sound dampeners & mufflers, catalytic converters, electrodes, heat exchangers, filters, etc. During post-processing of additive manufactured components using secondary machining to obtain required dimensional tolerance and/or surface quality, part porosity could lead to fluctuating cutting forces and reduced tool life. The machinability of the porous AM material is poor compared to the homogenous wrought material due to the intermittent cutting and anisotropy of AM materials. The cutting parameters for machining are generally optimized for continuous wrought material and are not applicable for porous AM material. Micromilling experiments were carried out on AM Ti6Al4V alloy with different porosity levels and cutting speed using a 1 mm diameter end mill. The progression of tool wear and associated mechanisms during micro-milling of additive manufactured Ti6Al4V samples with different porosity levels are experimentally investigated. Insights into tool-workpiece interaction during micro-machining are obtained in cases where pore size could be comparable to the cutting tool diameter. This research could lead to efficient hybrid additive-subtractive manufacturing technologies with improved tool life and reduced costs.
Cold Spray Multilayer Metal Build-Up on a Polymeric Substrate
Authors: Tsai Jung-Ting , Jun Martin Byung-Guk , Bahr David F. 
Published: September 2022

Abstract
Copper (Cu) and Tin (Sn) were low-pressure cold sprayed onto polyamide 6 (PA 6) and polypropylene (PP) substrates. The first layer of Sn and Cu was built onto the polymer substrate and continued as an alternative layer of Cu and Sn build-up under controlled process parameters. The chronological order of either first spraying Cu or Sn does not hinder building a coated layer on the PA 6 and PP substrate. The coating thickness can reach as thick as 100 μm of the PA 6 (Cu/Sn/Cu) layer. Results show the potential ability for additive manufacturing using polymeric templates. The cold spray kinetic bonding of the metals avoids any intermediate phase formation. The mechanical performance of the coated material remains the same as the deposition process does not degrade bulk substrates. The contour of the interface and the surface roughness resulting from the cold spray coating process lead to a deformed surface layer of the polymer on the particle size of the powder used for cold spraying. While the metallic coating deforms via plastic deformation and cracking, the through-thickness cracks, which primarily are perpendicular to the loading direction, do not span the width of the coating due to the tortuous nature of the microstructure. The advantage provides electrical conductivity to strains of up to 10% and maintains a low electrical resistance.
Experimental and Numerical Investigation of Short-Term Bio-Degradation Behavior of 3D Printed PLA
Authors: Ilhan Recep , Senaysoy Safa , Lekesiz Huseyin 
Published: September 2022

Abstract
There has been an increasing interest for biodegradable polymers in recent years because they can be formed as scaffolds and safely removed from the body without the need for any surgical operation, and contribute to the healing process. However, the main problem in polymer-based biodegradable materials is the inability to obtain tunable biodegradation behavior to match healing, which limits the clinical feasibility of these biomaterials. In this study, it is aimed to model biodegradation behavior from short term experimental data in an effort to reduce time required for determination of bio-degradation parameters. Thus, the degradation behavior can be determined and controlled at a lower cost. In this context, the biodegradation behavior of poly-lactic acid (PLA) polymer which is widely used in biomedical applications, was investigated experimentally and numerically on different days related to fracture bone healing times (5–12 weeks). First, 4.5 mm × 4.5 mm × 4.5 mm cubes were printed using the fused deposition modelling (FDM). Then, printed samples were exposed to degradation in the incubator by immersion in phosphate buffered saline (PBS) solution at 37 °C at physiological conditions for different time periods (0, 15, 30, 61 and 90 days). Throughout degradation, water absorption, weight loss, mechanical properties and morphological changes were investigated. Water absorption increases up to 13% within 61 days and then decreases to 10% within 90 days. On the other hand, samples gain 1% weight for the first 15 days and following, start losing weight around 0.3% percent at the end of 90 days. This clearly indicates that degradation occurs and water replaces the degraded material. There are fluctuations in the stiffness values that decrease on the 15 and 61 days but they increase on the 30th and 90th days. The increases in stiffness can be attributed to the compressive resistance of the trapped water content. Microscopic investigation clearly verifies the water content that the colors of the samples (opacity increase) changed while no significant change in its size occurred at different degradation days. Experimental results indicate a degradation and mechanical behavior variation throughout the process while dimensional stability during the 90 day degradation period. Numerical model predicts the stiffness values reasonably well within 15 and 30 days of degradation, but differences for 61 and 90 days. This difference possibly stems from the fact that the numerical model does not include any water inclusion disturbance.