bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rheological Measurement of the Gelation Temperature of Thermoresponsive Hydrogels: A Tutorial Using Pluronic F127
Authors: Zhang Haipeng , Ryu Sangjin , Ren Rongguo , Wang Dong 
Published: October 2020

Abstract
Pluronic F127 is a thermoresponsive hydrogel well used for various pharmaceutical applications. An emulsion of F127 can be gelated by heating the mixture, and this thermoresponsive gelation property enables local drug delivery. Thus, it is important to measure the gelation temeperature of F127 and similar thermoresponsive hydrogels for characterizing their gelation process for such applications.
Gelation temperature (Tgel) is a temperature threshold indicating the presence of network formation in F127 and similar thermoresponsive hydrogel materials. A widely used method for Tgel measurement is to measure Tgel based on changes in the storage modulus (G′) and loss modulus (G″) of the hydrogel with respect to temperature. However, this rheological measurement requires careful choices of measurement conditions. In this paper, we present the detailed tuning steps and results of our rheological Tgel measurement of F127 using a rotational rheometer as a tutorial for other researchers.
First, oscillation strain sweep measurements were performed to determine an optimum strain value in the linear viscoelastic region. Second, oscillation frequency sweep measurements were conducted to choose a reasonable oscillation frequency value. Third, G′ and G″ of F127 (25% w/v) were measured in the oscillation temperature sweep mode for the temperature range of 5°C to 45°C with the determined shear strain (0.1%) and oscillation frequency (1 rad/s). Last, Tgel was determined based on the crossover between measured G′ and G″ curves. Additionally, we compared the temperature sweep mode and the temperature ramp mode, and investigated effects of preshearing duration on repeated G′-G″ measurement and Tgel determination. The summarized procedure can be used as a reference to perform reliable and repeatable rheological Tgel measurement of thermoresponsive hydrogel materials.
A LES Study of Ventilation Flow Through a 3-D Room Fitted With Solar Chimney
Authors: Huynh B. Phuoc 
Published: October 2020

Abstract
Solar chimney (thermal chimney) is a device which absorbs solar radiation to heat the air. The heated air, becoming buoyant, rises through the chimney’s passage and induces further air currents. When fitted to a building, solar chimney can thus induce fresh outside air to flow through the building for ventilation. Because only natural means (solar radiation here) are involved to cause the air flow, solar chimney is considered a natural-ventilation device. This work investigates computationally natural ventilation induced by a roof-mounted solar chimney through a real-sized 3-dimensional room, using a commercial CFD (Computational Fluid Dynamics) software package which employs the Finite Volume Method. A LES (Large-Eddy Simulations) formulation with Smagorinsky SGS (Sub-Grid Scale) model is used. All fluid properties are assumed to be constant and corresponding to those of air at 300K (27°C, constant ambient temperature) and standard pressure at sea level (101.3kPa); but Boussinesq approximation (wherein temperature change affects only the fluid density pertaining to buoyancy force) is also assumed. Comparison is made with computational results obtained from a RANS (Reynolds-Averaged Navier-Stokes) formulation. Agreement between LES and RANS results indicate the trustworthiness of CFD methods used.
Fluid-Structure Interaction Modeling and Validation of Idealized Left Ventricular Blood Flow
Authors: Laughlin Megan , Stephens Sam , Jensen Hanna , Jensen Morten , Millett Paul 
Published: October 2020

Abstract
Fluid Structure Interaction (FSI) models are an essential tool in understanding the complex coupling of blood flow in the heart. The objective of this study is to establish a method of comparing data obtained from FSI models and benchtop measurements from phantoms to identify sources of flow changes for use in intraventricular flow analysis.
Two geometries are considered: 1) a vascular model consisting of a straight channel with an ellipsoidal swell and 2) an idealized left ventricle (LV) model representative “acorn” shape. Two phantoms are created for each of the two geometries: 3D printed rigid phantoms from a resin and custom-made tissue-mimicking phantoms from a medical gel. Benchtop measurements are made using the phantoms within a custom flow loop setup with pulsatile flow.
Computational Fluid Dynamics (CFD) simulations are conducted with a Smoothed Particle Hydrodynamics (SPH) model. The two flow channel geometries utilized in the experiments are replicated for the simulations. The cavity walls are defined by ghost particles that are rigidly fixed.
Maximum pressure drops were 57 mmHg and 196 mmHg for the rigid swell and rigid LV, respectively, whereas maximum pressure drops were 155 mmHg for the gel swell and 140 mmHg for the gel LV. Calculations from the simulations resulted in a maximum pressure drop of 55 mmHg for the swell and 110 mmHg for the LV. This data serves as a first step in corroborating our methodology to utilize the information obtained from both methods to identify and better understand mutual sources of changes in flow patterns.
Modeling the Effect of Spacer Grid and Mixing Vanes in Coupled CFD Simulations of Small Modular Reactors
Authors: Fang Jun , Shaver Dillon , Merzari Elia 
Published: October 2020

Abstract
Complex flow structure interaction and heat transfer process take place in the nuclear reactor cores. Given the extreme pressure/temperature and radioactive conditions in the core, numerical simulations offer an attractive (and sometimes more feasible) approach to study the related flow and heat transfer phenomena compared to experiments. Meanwhile, the rapid development and deployment of high-performance computing (HPC) facilities are helping unlock the even greater potential of massively parallel numerical simulations. Under the Exascale Computing Project, this study aims to develop suitable momentum sources that can reproduce the effects of spacer grid and mixing vanes (SGMV) on the core coolant flow. The ultimate project goal is to simulate the full core of a small modular reactor (SMR) with coupled thermal-hydraulics and neutronics. Modeling the SGMV effect without body-fitted computational grid avoids the excessive costs in resolving the local geometric details, and supports all the simulation to be scaled up to larger domain sizes. Thus, it is a crucial steppingstone to achieve the full core simulation on upcoming exascale supercomputers. This paper presents the preliminary results on the momentum source modeling as well as the roadmap for future research.
A Numerical Study of Mesh Type, Size, and Near Wall Grid Thickness Effect on Performance and Erosion Simulations in an Electrical Submersible Pump (ESP)
Authors: Zhu Haiwen , Lin Zimo , Peng Jianlin , Zhang Hong-Quan , Zhu Jianjun , Zhang Jun 
Published: October 2020

Abstract
The performance of multi-stage Electrical Submersible Pumps (ESPs) under different flow conditions and its life span with sand production are commonly predicted by the Computational Fluid Dynamics (CFD) simulations. The mesh generation methodology and optimum grid number are usually validated by pump water catalog curves. Then, the validated mesh geometry is adopted in high viscosity, multiphase flow, and sand erosion simulations to study the effects including but not limited to: discrete phase bubble diameter, turbulence model, body forces, and erosion models. However, the mesh validation by pump water curves is not enough in complex flow conditions, especially in the erosion simulations. Different from the pump hydraulic performance simulation, the accuracy of the erosion simulation can be affected by mesh boundary and inner layer grid thickness, especially for small particles. In addition, the mesh-type (hexahedral and tetrahedral) and size of the inner domain can also significantly affect the particle trajectory. A comprehensive mesh independent study is conducted for water, oil, and gas-liquid conditions of a mixed type ESP in this paper. Then the near-wall inflation layer thickness and inner domain grid size effect to ESP erosion simulation are well analyzed. The mesh generation methodology can be applied to other turbomachinery simulations to improve accuracy.
A Comparative Study of Interpolation Schemes in Overset Meshes for the PLIC-VOF Method in Multiphase Flows
Authors: Chang Yanni , Dai Dezhi , Tong Albert Y. 
Published: October 2020

Abstract
Piecewise Linear Interface Calculation (PLIC) schemes have been extensively employed in the Volume-of-Fluid (VOF) method for interface capturing in numerical simulations of multiphase flows. Dynamic overset meshes can be especially useful in applications involving component motions and complex geometric shapes. The basic idea of the overset mesh is the variable field interpolation within the overlapped region between the background and body meshes. The acceptor cell value is evaluated by a weighted average of its donors. The weighting factors are calculated by different algebraic methods, such as the averageValue, injection and inverseDistance schemes, which are implanted in the foam-extend library. A geometric interpolation scheme of the VOF field in overset meshes for the PLIC-VOF method has been proposed in the present study. The VOF value of an acceptor cell is evaluated geometrically with the reconstructed interfaces from the corresponding donor elements. Test cases of advecting liquid columns of different shapes inside a unit square/cube with a prescribed rotational velocity field have been performed to demonstrate the accuracy of the proposed overset interpolation scheme by comparing it with three algebraic ones. The proposed scheme has been shown to yield higher accuracy.
Analyzing the Characteristics of the Turbulent Vortices at Fast Rolling on Solid Surfaces
Authors: Radulescu Victorita 
Published: October 2020

Abstract
The present paper illustrates a new method for solving the two-dimensional turbulent fluid flow, for an incompressible fluid, near solid walls. Equations of energy conservation and momentum for thin layers have been used and solved with a slip velocity implemented in the Navier-Stokes equations. As a first step, a pseudo-laminar analysis was made. In parallel, some other models for turbulence were analyzed, to estimate the most appropriate model in conformity with the obtained experimental results. The numerical simulation was performed to investigate the effects of the Reynolds number on the flow characteristics, over a two-dimensional rectangular body and a curved shape surface. It was used the CFD, near the solid surfaces with a strong adverse pressure gradient. The viscous layer is expressed as an integral solution, imposing the wall shear stress as a boundary condition on solid surfaces. The velocity and shear stress are deduced from the Navier-Stokes equations as long as the convergence is reached. Numerical modeling was tested for Reynolds numbers ranging from 2040 to 13000. Firstly, the theoretical model for the flow equations and velocity distribution is described. Some details are presented for estimating as better as possible the wall velocity and the shear stresses. Numerical modeling, with the FEM model, is based on the Galerkin formulation. Some aspects referring to the boundary conditions, for the analyzed cases are also mentioned. The flow is restricted at a central vortex, considered the primary vortex. In turbulent boundary layer, for the analyzed applications were not considered the axial vortices. Some aspects referring to the flow domain and the grid generation are mentioned in a dedicated paragraph. For numerical modeling, firstly was adopted the non-viscous solution, as the initial condition. It depends on the available information concerning the shapes geometry, the curvature radius, and the flow conditions for the considered problems. For the first approximation, was used the integral boundary-layer method, which can provide a proper solution. The advantage consists of reducing the number of iteration to reach the numerically final settlement. If it will be used the integral method, will be provided only an approximate distribution for the edge velocity. Variation of the reattachment length of vortices over the analyzed solid bodies is correlated with the experimental results from the literature. Exclusive analysis of the selected data shows that the turbulent values correlated directly to the body length-b are more accurate than those referring to the dimensionless rapport δ/b. From the analyzed models, the K-ε model presents better agreement with experimental data, also for the negative values of the Reynolds shear stress in the re-attachment point. Finally, some conclusions and references are mentioned.
A Hepatic Sinusoids-Based Microreactor for Photocatalytic Degradation of Methylene Blue by Titanium Dioxide
Authors: Shouman Mahmoud A. , El-Shazly Ahmed H. , Salem Mohamed S. , Elmarghany Mohamed R. , Abo-Zahhad Essam M. , Elkady Marwa F. , Sabry Mohamed Nabil , Radwan Ali 
Published: October 2020

Abstract
Microreactor technology is considered a state of art technology that gained great attention from researchers due to the high effectiveness and the small residence time compared with other regular reactors. Great research work has been established to involve microreators in a variety of applications, including fuel production, food and chemical industries, medical applications. In the present study, a hepatic sinusoids-based microreactor is experimentally tested in Methylene blue degradation using titanium dioxide (TiO2) photocatalyst activated with ultraviolet lamp of wavelength 365 nm. Purification of water using photocatalysis is considered a promising technology that attract the industrial community. Different operating conditions are investigated including; flow rate, Methylene blue concentration, and TiO2 concentration. 3 different dye concentrations are used (10 ppm, 20 ppm, and 30 ppm) with 3 different photocatalyst concentrations (100 ppm, 300 ppm, and 500 ppm). The flow rate has a span from 0.25 ml/min to 1 ml/min. Experiments are conducted to determine best operating conditions. Results show that the microreactor system can be effectively used in dye degradation with a very small residence time. A degradation of over 95% was reached at a TiO2 concentration of 300 ppm and a flow rate of 0.25 ml/min for all tested dye concentrations.
Numerical and Experimental Investigation on Evaporation of Water Droplet on Surfaces With Mixed Wettability
Authors: Aboubakri Akam , Yanik Cenk , Akkuş Yiğit , Koşar Ali , Sadaghiani Ali K. 
Published: October 2020

Abstract
Droplet evaporation is one of the most commonly observed phenomena and plays an important role in many applications such as in spray cooling, coating, and inkjet printing. Mechanisms such as dynamics of the contact line, evaporation-induced phase transitions, and formation of patterns on the substrate interact with each other in the evaporation of droplets. In this study, we investigated the effect of surface mixed wettability on water sessile droplet evaporation. The transient contact angle, center-height, contact radius, surface area, and droplet volume were experimentally measured and numerically estimated. Surfaces with mixed wettability consisting of hydrophilic islands surrounded by less hydrophilic area were fabricated. Visualization was conducted to capture droplet dynamics during evaporation using two high-speed cameras. According to the obtained results, there were three distinct stages in the water evaporation process: a constant contact radius mode, a constant contact angle mode, and a mixed-mode. The COMSOL 5.4 software was used for numerical analysis. According to the results, the receding contact angle and Marangoni instability in the droplet are two main factors that alter droplet dynamics and droplet evaporation.
Streamer Formation in Particle Laden Polymeric Flows
Authors: Chandra Navin Kumar , Kumar Aloke , Ghosh Ranajay 
Published: October 2020

Abstract
Particle laden polymeric flows are of interest to the fluid mechanics community due to the possibility of flow induced aggregation and structure formation. Here, we show that when particle laden polymeric suspensions flow through an annular area at moderate Reynolds numbers (∼ 10) and Weissenberg numbers (∼ 10−2–10−1), it can result in formation of flow induced structures. Specifically, the particle can aggregate in the form of thin slender, flexible structures called streamers. The name ‘streamer’ is inspired by their slender morphology which is similar to bacterial streamers formed in bacterial aggregation subjected to continuous hydrodynamic flow. In the present work, polyethylene oxide (PEO) and dry gram flour has been used to create particle laden polymeric fluid suspension. The Taylor-Couette geometry has been modified by employing a stationary needle in the annular space to study the effect of varying hydrodynamic conditions on streamer formation and their morphology. Experimental observations show that depending on the polymer to particle concentration ratio (Cpolymer/Cparticle) and the hydrodynamic condition, different morphologies of streamers can be obtained. This is collated in the form of a state diagram. Surprisingly, it is observed that aged polymeric suspensions enhance streamer formation when employed in conjunction with gram flour powder that function as colloidal particles. Zeta potential and rheological measurements have been performed to gain further insights on the change in properties of polymer on account of ageing.
Quantitative Morphology of Cerebral Thrombi Related to Intravital Contraction and Clinical Features of Ischemic Stroke
Authors: Khismatullin Rafael R. , Nagaswami Chandrasekaran , Shakirova Asia Z. , Vrtková Adéla , Procházka Václav , Gumulec Jaromír , Mačák Jiří , Litvinov Rustem I. , Weisel John W. 
Published: October 2020

Background and Purpose:
The purpose was to assess quantitatively and qualitatively the composition and structure of cerebral thrombi and correlate them with the signs of intravital clot contraction (retraction), as well as with etiology, severity, duration, and outcomes of acute ischemic stroke.

Methods:
We quantified high-resolution scanning electron micrographs of 41 cerebral thrombi for their detailed cellular and noncellular composition and analyzed histological images for the overall structure with the emphasis on red blood cell compression, fibrin age, and the signs of inflammation.

Results:
Cerebral thrombi were quite compact and had extremely low porosity. The prevailing cell type was polyhedral compressed erythrocytes (polyhedrocytes) in the core, and fibrin-platelet aggregates were concentrated at the periphery; both findings are indicative of intravital contraction of the thrombi. The content of polyhedrocytes directly correlated with the stroke severity. The prevalence of fibrin bundles was typical for more severe cases, while the content of fibrin sponge prevailed in cases with a more favorable course. The overall platelet content in cerebral thrombi was surprisingly small, while the higher content of platelet aggregates was a marker of stroke severity. Fibrillar types of fibrin prevailed in atherothrombogenic thrombi. Older fibrin prevailed in thrombi from the patients who received thrombolytics, and younger fibrin dominated in cardioembolic thrombi. Alternating layers of erythrocytes and fibrin mixed with platelets were common for thrombi from the patients with more favorable outcomes. Thrombi with a higher number of leukocytes were associated with fatal cases.

Conclusions:
Most cerebral thrombi undergo intravital clot contraction (retraction) that may be of underestimated clinical importance. Despite the high variability of the composition and structure of cerebral thrombi, the content of certain types of blood cells and fibrin structures combined with the morphological signs of intravital contraction correlate with the clinical course and outcomes of acute ischemic stroke.
Higher-Order Cognition Does Not Affect Multisensory Distractor Processing
Authors: Merz Simon , Jensen Anne , Burau Charlotte , Spence Charles , Frings Christian 
Published: October 2020

Abstract
Multisensory processing is required for the perception of the majority of everyday objects and events. In the case of irrelevant stimuli, the multisensory processing of features is widely assumed to be modulated by attention. In the present study, we investigated whether the processing of audiovisual distractors is also modulated by higher-order cognition. Participants fixated a visual distractor viewed via a centrally-placed mirror and responded to a laterally-presented audiovisual target. Critically, a distractor tone was presented from the same location as the mirror, while the visual distractor feature was presented at an occluded location, visible only indirectly via mirror reflection. Consequently, it appeared as though the visual and auditory features were presented from the same location though, in fact, they actually originated from different locations. Nevertheless, the results still revealed that the visual and auditory distractor features were processed together just as in the control condition, in which the audiovisual distractor features were both actually presented from fixation. Taken together, these results suggest that the processing of irrelevant multisensory information is not influenced by higher-order cognition.
Orthotic treatment for stage I and II posterior tibial tendon dysfunction (flat foot): A systematic review
Authors: Gómez-Jurado Isabel , Juárez-Jiménez José María , Munuera-Martínez Pedro V 
Published: October 2020

Objective: To investigate whether orthotic treatment is effective for the treatment of posterior tibial tendon dysfunction stages I and II (flat foot). Data Sources: Five databases (PubMed, Scopus, PEDro, SPORTDiscus and The Cochrane Library) were searched for potential RCTs from their inception until August 2020. Review Methods: Only randomised controlled trials (RCT) that included subjects diagnosed with posterior tibial dysfunction in the initial stage and treated with orthotic treatments were selected. The outcomes assessed were whatever symptom related to posterior tibial tendon dysfunction stage I and II. Included RCTs were appraised using the Cochrane collaboration risk of bias tool. Results: Four RCT articles and 186 subjects were included. 75% were at high risk of bias for blinding of participants and personnel. Three different types of conservative treatment were used in the studies: foot/ankle-foot orthoses, footwear and stretching /strengthening exercises. Foot orthoses, together with exercise programmes, seemed to improve the effect of orthotic treatment. Foot orthoses with personalised internal longitudinal arch support were more effective than flat insoles or standard treatments in reducing pain. Conclusions: The use of orthotic treatment may be effective in reducing pain in the early stages of posterior tibial tendon dysfunction. Further research is needed into individualised orthotic treatment and high-intensity monitored exercise programmes.