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Chinese Journal of Aeronautics 2022年第4期35卷 55-65页

作者： Jisong ZHAO Jinming ZHANG Boqiao WANG College of Astronautics Nanjing University of Aeronautics and AstronauticsNanjing 210016China Faculty of Rocket and Space Technology Kharkiv Aviation InstituteNational Aerospace UniversityKharkiv 61070Ukraine

A learning-based approach for solving wall shear stresses from shear-Sensitive Liquid Crystal Coating(SSLCC) color images is presented in this paper. The approach is able to learn and establish the mapping relationship between the SSLCC color-change responses in different observation directions and the shear stress vectors, and then uses the mapping relationship to solve wall shear stress vectors from SSLCC color images. Experimental results show that the proposed approach can solve wall shear stress vectors using two or more SSLCC images, and even using only one image for symmetrical flow field. The accuracy of the approach using four or more observations is found to be comparable to that of the traditional multi-view Gauss curve fitting approach;the accuracy is slightly reduced when using two or fewer observations. The computational efficiency is significantly improved when compared with the traditional Gauss curve fitting approach, and the wall shear stress vectors can be solved in nearly real time. The learning-based approach has no strict requirements on illumination direction and observation directions and is therefore more flexible to use in practical wind tunnel measurement when compared with traditional liquid crystal-based methods.

关键词： shear stress Measurement shear-sensitive liquid crystal Learning-based approach Calibration

Heat Transfer of Casson Fluid over a Vertical Plate with Arbitrary shear stress and Exponential Heating

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Computers, Materials & Continua 2022年第4期71卷 1025-1034页

作者： Dolat Khan Gohar Ali Arshad Khan Ilyas Khan Department of Mathematics City University of Science and Information TechnologyPeshawar25000Pakistan Institute of Computer Sciences and Information Technology The University of AgriculturePeshawarPakistan Faculty of Mathematics and Statistics Ton Duc Thang UniversityHo Chi Minh City72915Vietnam

The basic objective of this work is to study the heat transfer of Casson fluid of non-Newtonian nature.The fluid is considered over a vertical plate such that the plate exhibits arbitrary wall shear stress at the boundary.Heat transfers due to exponential plate heating and natural convection are due to buoyancy force.Magnetohydrodynamic(MHD)analysis in the occurrence of a uniform magnetic field is also considered.The medium over the plate is porous and hence Darcy’s law is applied.The governing equations are established for the velocity and temperature fields by the usual Boussinesq approximation.The problem is first written in dimensionless form using some useful non-dimensional quantities and then solved.The exact analysis is performed and hence solutions via integral transform are established.The analysis of various pertinent parameters on temperature distribution and velocity field are reported graphically.It is found that pours medium permeability parameter retards the fluid motion whereas,velocity decreases with increasing magnetic parameter.Velocity and temperature decrease with increasing Prandtl number whereas the Grashof number enhances the fluid motion.Further,it is concluded from this study that the results obtained here are more general and in a limiting sense several other solutions can be recovered.The Newtonian fluid results can be easily established by taking the Casson parameter infinitely large i.e.,whenβ→∞.

关键词： Heat transfer casson fluid shear stress natural convection

Evolution of wall flow structure and measurement of shear stress issuing from supersonic jet with extended shelf

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Chinese Journal of Aeronautics 2021年第11期34卷 94-105页

作者： Yun JIAO Chengpeng WANG Jiaqi XIE Kang LI Kerning CHENG College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Key Laboratory of Unsteady Aerodynamics and Flow Control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China

This paper reports an experimental study on the supersonic jet surface flow structure visualization and shear stress field measurement issuing from a rectangular nozzle with extended shelf. The evolution of the near-field surface flow structures with an increased Nozzle Pressure Ratio(NPR) is successfully captured by the surface oil flow, infrared detection technology, and the shear-Sensitive Liquid Crystal Coating(SSLCC) technique. Results reveal that under smaller NPR, the wall flow structure is similar to that of a jet without the extended shelf i.e., clean jets,and this is caused by insufficient effect on the boundary layer. However, at higher amplitudes of NPR, there exists a significant effect of the boundary layer, as a near triangular separation forms on the trailing edge of the Mach stem due to the adverse pressure gradient, which is visualized for the very first time in this paper. Furthermore, the vector field of shear stress is measured quantitatively by SSLCC technique. Results shows that the magnitude of shear stress heightened with NPR increasing, and the directions of shear stress changes across the shock wave and expansion fans. In addition, surface streamlines measured by SSLCC is significantly consistent with the streamlines visualized using the oil flow technique.

关键词： Evolution of shock structure Flow visualization Quantitative measurement shear stress Supersonic jet

Effect of intraplaque angiogenesis to atherosclerotic rupture-prone plaque induced by high shear stress in rabbit model

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Regenerative Biomaterials 2017年第4期4卷 215-222页

作者： Juhui Qiu Daoxi Lei Jianjun Hu Tieying Yin Kang Zhang Donghong Yu Guixue Wang Department of Bio-engineering Key Laboratory for Biorheological Science and Technology of Ministry of EducationState and Local Joint Engineering Laboratory for Vascular ImplantsBioengineering College of Chongqing UniversityChongqing 400044China

Atherosclerotic prone-rupture plaque is mainly localized in the region of the entrance to the stenosiswith high shear stress and the reasons are largely unknown. Our hypothesis is that such a distributionof cells in atherosclerotic plaque may depend on the angiogenesis. Silastic collars inducedregions of high shear stress (20.6865.27 dynes/cm2) in the upstream flow and low shear stress(12.2561.28 dynes/cm2) in the downstream flow in carotid arteries. Compared with the low shearstress region, plaques in the high shear stress region showed more intraplaque haemorrhaging,less collagen and higher apoptotic rates of vascular smooth muscle cells;endothelial cells (ECs) inthe high shear stress region were characterized with integrity and high endothelial nitric oxidesynthase (eNOS) expression (1570.36345.5% vs 172.9649.9%). The number of intraplaque microvesselsis very high in the high shear stress region (1561.8 n/mm2 vs 3.560.4 n/mm2), and themicrovessels in the plaque show ECs were abnormal, with membrane blebs, intracytoplasmic vacuolesand leukocyte infiltration. Our current study reveals that the integrity of the endothelium andthe vulnerability of atherosclerotic plaques are simultaneously localized in high shear stress regions,and we provide evidence for the first time that microvessels in the intraplaque maybe responsiblefor rupture-prone plaque formation in the high shear stress region.

关键词： angiogenesis atherosclerosis shear stress prone-rupture plaque

Critical shear stress approach for self-cleansing design of a rectangular channel

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International Journal of Sediment Research 2021年第5期36卷 678-685页

作者： Charles Hin Joo Bong San Chuin Liew Fang Yenn Teo Tze Liang Lau Aminuddin Ab Ghani Faculty of Engineering Universiti Malaysia Sarawak 2. Faculty of Engineering Computing and Science Swinburne University of Technology Sarawak Campus 3. Faculty of Science and Engineering University of Nottingham Malaysia 4. School of Civil Engineering Universiti Sains Malaysia Engineering Campus River Engineering and Urban Drainage Research Centre (REDAC) Universiti Sains Malaysia Engineering Campus

The current study aims at the development of an incipient motion equation and a self-cleansing design chart based on the critical shear stress approach for a rectangular channel. Data from previous experimental work on incipient motion for rectangular flumes were subjected to multiple linear regression analysis. Selected regression models were further assessed through cross validation using the remaining data from the previous experimental work and a performance test using another three sets of existing data from the literature. The best regression model from the current study was found to perform much better than two of the existing equations in the literature by Novak and Nalluri and El-Zaemey with respect to having 95% of the predicted values fall within the acceptable discrepancy ratio range of 0.5 e2.0. The equations by Novak and Nalluri and El-Zaemey only managed to have 10% and 16%, respectively, of the predicted values fall within the acceptable discrepancy ratio. The developed best regression model has a coefficient of determination (Rp2) value of 0.9960, adjusted coefficient of determination (Radj2)value of 0.9960, predicted coefficient of determination (Rpre2) value of 0.9958, mean square error(MSE)value of 0.0004, and Mallow’s Cpvalue of 3.0. The best regression model was further chosen to develop a self-cleansing design chart for rectangular channels. The design chart which relates the minimum sewer slope Sminwith the minimum critical shear stress, tc, for the respective standard rectangular channel size of an open channel system could be used to check and determine the suitable minimum slope for selfcleansing design purposes.

关键词： Design chart Incipient motion equation Open channel system Rectangular channel Self-cleansing shear stress

Design of Measuring Instrument with Whole Direct Method for Bed shear stress Under Two-Dimensional Water-Flow Co-action

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China Ocean Engineering 2016年第6期30卷 916-925页

作者：黄海龙左其华周益人沈雨生李蓝汐 Nanjing Hydraulic Research Institute Nanjing 210029China Key Laboratory of Port Waterway and Sedimentation Engineering of MOTNanjing 210024China Business School Hohai UniversityNanjing 210098China

The present study aims at the design and making of measuring instrument of whole direct method for bed shear stress under two-dimensional water-flow co-action. The instrument combines the traditional strain gauge with a precise pressure gauge, and adopts the method directly measuring the difference between the lateral hydrodynamic pressure and different head pressures on both sides of the force plate. As a result, such an instrument solves a technical puzzle of the past strain gauge, i.e. the difficulty to set apart shear stress and lateral force. Static force test and sink test both prove that the instrument is precise, stable and applicable to the measurement of rough beds with different shear stresses.

关键词： direct method shear stress measurement

shear stress in MR Fluid with Small shear Deformation in Bctlattic Structure

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Journal of Wuhan University of Technology(Materials Science) 2008年第4期23卷 532-535页

作者： LIU Lisheng RUAN Zhongwei ZHAI Pengcheng ZHANG Qingjie State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

A theoretical model based on BCT lattice structure was developed. Resultant force in the BCT lattice structure was deduced, following the interaction force of two kinds of magnetic particles. According to empirical FroHlich-Kermelly law, the relationship between the magnetic induction and the magnetic field was discussed, and a predictive formula of shear stresses of the BCT lattice structure model was established for the case of small shear deformation. Compared with the experimental data for different particle volume fractions, the theoretical results of the shear stress indicate the effects of the saturation magnetization and the external magnetic field on the shear stress.

关键词： magnetorheological fluids （MR fluids） body-centered-tetragonal（BCT） interaction force shear stress small deformation

Microstreaming velocity field and shear stress created by an oscillating encapsulated microbubble near a cell membrane

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Chinese Physics B 2014年第12期23卷 270-276页

作者：王莉屠娟郭霞生许迪章东 Institute of Acoustics Key Laboratory of Modern Acoustics Ministry of Education Nanjing University The First Affiliated Hospital of Nanjing Medical University

Sonoporation mediated by microbubbles is being extensively studied as a promising technology to facilitate gene/drug delivery to cells. However, the theoretical study regarding the mechanisms involved in sonoporation is still in its infancy.Microstreaming generated by pulsating microbubble near the cell membrane is regarded as one of the most important mechanisms in the sonoporation process. Here, based on an encapsulated microbubble dynamic model with considering nonlinear rheological effects of both shell elasticity and viscosity, the microstreaming velocity field and shear stress generated by an oscillating microbubble near the cell membrane are theoretically simulated. Some factors that might affect the behaviors of microstreaming are thoroughly investigated, including the distance between the bubble center and cell membrane（d）, shell elasticity（χ）, and shell viscosity（κ）. The results show that（i） the presence of cell membrane can result in asymmetric microstreaming velocity field, while the constrained effect of the membrane wall decays with increasing the bubble-cell distance;（ii） the bubble resonance frequency increases with the increase in d and χ, and the decrease in κ,although it is more dominated by the variation of shell elasticity; and（iii） the maximal microstreaming shear stress on the cell membrane increases rapidly with reducing the d, χ, and κ. The results suggest that microbubbles with softer and less viscous shell materials might be preferred to achieve more efficient sonoporation outcomes, and it is better to have bubbles located in the immediate vicinity of the cell membrane.

关键词： microstreaming shear stress sonoporation encapsulated microbubbles

Membrane fluidity regulates high shear stress-induced FAK activation at different subcellular compartments

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BIOCELL 2017年第2期41卷 45-53页

作者： FEI XIE BAOHONG ZHANG WENFENG XU XIAOLING LIAO QIUHONG HUANG BO LIU Institute of Biomedical Engineering Chongqing Engineering Laboratory of Nano/Micro Biological Medicine Detection TechnologyChongqing University of Science and TechnologyChongqing401331China School of Biomedical Engineering Dalian University of TechnologyDalian116024China

Focal adhesion kinase(FAK)plays a vital role in mediating the adaptability of tumor cells under mechanical stimuli.Previous studies revealed that FAK can locate to different cell compartments,and its regulation is highly dependent on its subcellular localization.However,the local FAK activities and its regulation mechanism in different cell compartments of tumor cells in response to fluid shear stress are still unclear.In this study,5 dyn/cm^(2) and 20 dyn/cm^(2) of shear stress was applied to HeLa cells for 30 min.The activities of FAK targeting different subcellular compartments(lipids rafts,non-rafts,focal adhesions and cytoplasm)were investigated with fluorescence resonance energy transfer(FRET)technology.Results showed that the activity of FAK in response to high shear stress at focal adhesion sites was lower than that of other three areas,while no difference among four areas was observed in response to low shear stress.Furthermore,high shear stress-induced distinct FAK activation at different compartments was inhibited by decreasing membrane fluidity,but Src inhibition prevented high shear stress-induced FAK activation only in the cytoplasm.This study revealed the spatiotemporal characteristics of FAK under the different magnitude of shear stress,which provides a deeper understanding of mechanotransduction in tumor cells.

关键词： FAK activity shear stress FRET biosensor

Effects of shear stress on differentiation of stem cells into endothelial cells

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World Journal of Stem Cells 2021年第7期13卷 894-913页

作者： Yan Huang Jia-Yi Qian Hong Cheng Xiao-Ming Li Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education Beijing Advanced Innovation Center for Biomedical EngineeringSchool of Biological Science and Medical EngineeringBeihang UniversityBeijing 100083China

Stem cell transplantation is an appealing potential therapy for vascular diseases and an indispensable key step in vascular tissue engineering.Substantial effort has been made to differentiate stem cells toward vascular cell phenotypes,including endothelial cells(ECs)and smooth muscle cells.The microenvironment of vascular cells not only contains biochemical factors that influence differentiation but also exerts hemodynamic forces,such as shear stress and cyclic strain.More recently,studies have shown that shear stress can influence the differentiation of stem cells toward ECs.A deep understanding of the responses and underlying mechanisms involved in this process is essential for clinical translation.This review highlights current data supporting the role of shear stress in stem cell differentiation into ECs.Potential mechanisms and signaling cascades for transducing shear stress into a biological signal are proposed.Further study of stem cell responses to shear stress will be necessary to apply stem cells for pharmacological applications and cardiovascular implants in the realm of regenerative medicine.

关键词： shear stress Stem cells Cell differentiation Endothelial cells Mechanotransduction