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Experimental observation on water entry of a sphere in regular wave
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作者 Qian Wang Changze Zhao +1 位作者 Haocheng Lu Hua Liu 《Theoretical & Applied Mechanics Letters》 CSCD 2023年第5期367-374,共8页
This paper presents a novel experiment to observe the whole water entry process of a free-falling sphere into a regular wave.A time-accurate synchronizing system modulates the moment elaborately to ensure the sphere i... This paper presents a novel experiment to observe the whole water entry process of a free-falling sphere into a regular wave.A time-accurate synchronizing system modulates the moment elaborately to ensure the sphere impacting onto the water surface at the desirable wave phase.Four high-speed cameras focus locally to measure the high-precision size of the cavity evolution.Meanwhile,the aggregated field view of the camera array covers both the splash above the free surface and the entire cavity in the wave.The detailed methodologies are described and verified for the hardware set-up and the image post-processing.The theoretical maximum deviation is 1.7%on the space scale.The integral morphology of the cavity is captured precisely in the coordinate system during the sphere penetrates through the water at four representative wave phases and the still water.The result shows that the horizontal velocity of the fluid particle in the wave impels the cavity and changes the shape distinctly.Notably,the wave motion causes the cavity to pinch offearlier at the wave trough phase and later at the wave crest phase than in the still water.The wave motion influences the falling process of the sphere slightly in the present parameters. 展开更多
关键词 Physical experiment Water entry Free-falling sphere Regular wave
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A Comparison of Conventional and Shear-Rate Dependent Mohr-Coulomb Models for Simulating Landslides 被引量:5
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作者 LIANG Dong-fang HE Xu-zhen 《Journal of Mountain Science》 SCIE CSCD 2014年第6期1478-1490,共13页
Landslides may cause many fatalities and heavy economic losses,so it is vital to understand their mechanics so as to take appropriate measures to mitigate their risk.Phenomenally,the loose soil behaves like frictional... Landslides may cause many fatalities and heavy economic losses,so it is vital to understand their mechanics so as to take appropriate measures to mitigate their risk.Phenomenally,the loose soil behaves like frictional material in most circumstances,so Mohr-Coulomb type equations are often used to describe their movement.However,these models generally do not consider the influence of the shearrate on the Mohr-Coulomb friction angle,so the shear-rate dependence effect on the soil flow and landslide runout is not well understood.This paper reports on an application of the incompressible Smoothed Particle Hydrodynamics(SPH) method to the dynamics of dry granular assemblies.The traditional model with a constant friction angle is compared with the modified Mohr-Coulomb model with a variable friction angle related to the shear-rate.It is found that the shear-rate dependence effect is negligible for shallow granular flows along mild slopes.With steeper slopes of the ground and larger aspect ratios of the initial soil column,the rate-dependence effect becomes more important. 展开更多
关键词 剪切速率 模型模拟 MOHR-COULOMB模型 莫尔 库仑 坡比 山体滑坡 粒子动力学
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Fluid-structure interaction simulation of three-dimensional flexible hydrofoil in water tunnel 被引量:6
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作者 Shiliang HU Chuanjing LU Yousheng HE 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2016年第1期15-26,共12页
The closely coupled approach combined with the finite volume method (FVM) solver and the finite element method (FEM) solver is used to investigate the fluid-structure interaction (FSI) of a three-dimensional can... The closely coupled approach combined with the finite volume method (FVM) solver and the finite element method (FEM) solver is used to investigate the fluid-structure interaction (FSI) of a three-dimensional cantilevered hydrofoil in the water tunnel. The FVM solver and the coupled approach are verified and validated by compar- ing the numerical predictions with the experimental measurements, and good agreement is obtained concerning both the lift on the foil and the tip displacement. In the noncav- itating flow, the result indicates that the growth of the initial incidence angle and the Reynolds number improves the deformation of the foil, and the lift on the foil is increased by the twist deformation. The normalized twist angle and displacement along the span of the hydrofoil for different incidence angles and Reynolds numbers are almost uniform. For the cavitation flow, it is shown that the small amplitude vibration of the foil has limited influence on the developing process of the partial cavity, and the quasi two-dimensional cavity shedding does not change the deformation mode of the hydrofoil. However, the frequency spectrum of the lift on the foil contains the frequency which is associated with the first bend frequency of the hydrofoil. 展开更多
关键词 closely coupled approach fluid-structure interaction (FSI) hydrofoil cavitation
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Shedding Phenomenon of Ventilated Partial Cavitation around an Underwater Projectile 被引量:7
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作者 王一伟 黄晨光 +4 位作者 杜特专 吴先前 方新 梁乃刚 魏延鹏 《Chinese Physics Letters》 SCIE CAS CSCD 2012年第1期176-179,共4页
A new shedding phenomenon of ventilated partial cavitations is observed around an axisymmetric projectile in a horizontal launching experiment.The experiment system is established based on SHPB launching and high spee... A new shedding phenomenon of ventilated partial cavitations is observed around an axisymmetric projectile in a horizontal launching experiment.The experiment system is established based on SHPB launching and high speed photography.A numerical simulation is carried out based on the homogeneous mixture approach,and its predicted evolutions of cavities are compared with the experimental results.The cavity breaks off by the interaction between the gas injection and the re-entry jet at the middle location of the projectile,which is obviously different from natural cavitation.The mechanism of cavity breaking and shedding is investigated,and the influences of important factors are also discussed. 展开更多
关键词 CAVITATION BREAKING SYSTEM
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Numerical Simulation of Irregular Wave Overtopping Against A Smooth Sea Dike 被引量:5
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作者 郭晓宇 王本龙 刘桦 《China Ocean Engineering》 SCIE EI 2012年第1期153-166,共14页
Based on the filtered Navier-Stokes equations and Smagorinsky turbulence model, a numerical wave flume is developed to investigate the overtopping process of irregular waves over smooth sea dikes. Simulations of fully... Based on the filtered Navier-Stokes equations and Smagorinsky turbulence model, a numerical wave flume is developed to investigate the overtopping process of irregular waves over smooth sea dikes. Simulations of fully nonlinear standing wave and regular wave's run-up on a sea dike are carried out to validate the implementation of the numerical wave flume with wave generation and absorbing modules. To model stationary ergodic stochastic processes, several cases with different random seeds are computed for each specified irregular wave spectrum. It turns out that the statistical mean overtopping discharge shows good agreement with empirical formulas, other numerical results and experimental data. 展开更多
关键词 overtopping discharge irregular wave numerical wave flume Navier-Stokes equations
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A prediction of in vivo mechanical stresses in blood vessels using thermal expansion method and its application to hypertension and vascular stenosis 被引量:7
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作者 Shaoxiong Yang Lucy T.Zhang +4 位作者 Cheng Hua Yunqiao Liu Jingdong Tang Xiaobo Gong Zonglai Jiang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2018年第6期1156-1166,共11页
Mechanical stimuli play critical roles in cardiovascular diseases,in which in vivo stresses in blood vessels present a great challenge to predict.Based on the structural-thermal coupled finite element method,we propos... Mechanical stimuli play critical roles in cardiovascular diseases,in which in vivo stresses in blood vessels present a great challenge to predict.Based on the structural-thermal coupled finite element method,we propose a thermal expansion method to estimate stresses in multi-layer blood vessels under healthy and pathological conditions.The proposed method provides a relatively simple and convenient means to predict reliable in vivo mechanical stresses with accurate residual stress.The method is first verified with the opening-up process and the pressure-radius responses for single and multi-layer vessel models.It is then applied to study the stress variation in a human carotid artery at different hypertension stages and in a plaque of vascular stenosis.Our results show that specific or optimal residual stresses exist for different blood pressures,which helps form a homogeneous stress distribution across vessel walls.High elastic shear stress is identified on the shoulder of the plaque,which contributes to the tearing effect in plaque rupture.The present study indicates that the proposed numerical method is a capable and efficient in vivo stress evaluation of patient-specific blood vessels for clinical purposes. 展开更多
关键词 CARDIOVASCULAR disease In VIVO stress MULTI-LAYER VESSEL structure HYPERTENSION Stenosed VESSEL
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Scenarios of Local Tsunamis in the China Seas by Boussinesq Model 被引量:3
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作者 赵曦 刘桦 王本龙 《China Ocean Engineering》 SCIE EI CSCD 2014年第3期303-316,共14页
The Okinawa Trench in the East China Sea and the Manila Trench in the South China Sea are considered to be the regions with high risk of potential tsunamis induced by submarine earthquakes. Tsunami waves will impact t... The Okinawa Trench in the East China Sea and the Manila Trench in the South China Sea are considered to be the regions with high risk of potential tsunamis induced by submarine earthquakes. Tsunami waves will impact the southeast coast of China if tsunamis occur in these areas. In this paper, the horizontal two-dimensional Boussinesq model is used to simulate tsunami generation, propagation, and runnp in a domain with complex geometrical boundaries. The temporary varying bottom boundary condition is adopted to describe the initial tsunami waves motivated by the submarine faults. The Indian Ocean tsunami is simulated by the numerical model as a validation case. The time series of water elevation and runup on the beach are compared with the measured data from field survey. The agreements indicate that the Boussinesq model can be used to simulate tsunamis and predict the waveform and runup. Then, the hypothetical tsunamis in the Okinawa Trench and the Manila Trench are simulated by the numerical model. The arrival time and maximum wave height near coastal cities are predicted by the model. It turns out that the leading depression N-wave occurs when the tsunami propagates in the continental shelf from the Okinawa Trench. The scenarios of the tsunami in the Manila Trench demonstrate significant effects on the coastal area around the South China Sea. 展开更多
关键词 TSUNAMI Boussinesq model Indian Ocean Okinawa Trench Manila Trench
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Experimental Measurements of Solitary Wave Attenuation Over Shallow and Intermediate Submerged Canopy 被引量:3
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作者 王千 郭晓宇 +2 位作者 王本龙 房詠柳 刘桦 《China Ocean Engineering》 SCIE EI CSCD 2016年第3期375-392,共18页
Attenuations of solitary wave over a patch of submerged canopy are experimentally investigated. The submerged canopy is modeled by a group of circular cylinder array. The decay coefficients of different wave heights i... Attenuations of solitary wave over a patch of submerged canopy are experimentally investigated. The submerged canopy is modeled by a group of circular cylinder array. The decay coefficients of different wave heights in two water depths along the wave flume are measured for six canopy models, including two canopy heights and three styles of arrangements. The relationships among the decay coefficient, and the dimensionless wave height, submergence ratio, relative height and arrangement of the canopy are experimentally studied. 2D PIV technique is employed to measure the representative flow field inside the canopy. A four-deck flow structure is proposed for wave flow field over shallow submerged canopy. The characteristics of shear flow inside the aligned canopy region are discussed. 展开更多
关键词 Solitary waves submerged canopy rigid cylinders decay coefficient PIV
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Numerical Investigation of Run-ups on Cylinder in Steep Regular Wave 被引量:2
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作者 FAN Xiang ZHANG Jing-xin LIU Hua 《China Ocean Engineering》 SCIE EI CSCD 2019年第5期601-607,共7页
The run-up on offshore structures induced by the steep regular wave is a highly nonlinear flow with a free surface. This article focuses on the investigation of the steep regular wave run-up on a single vertical cylin... The run-up on offshore structures induced by the steep regular wave is a highly nonlinear flow with a free surface. This article focuses on the investigation of the steep regular wave run-up on a single vertical cylinder by solving the Navier-Stokes equations. A numerical wave tank is established based on the open-source package to simulate the wave scattering induced by a vertical cylinder. The VOF method is applied to capture the large deformation and breaking of the free surface. The numerical model is validated by experimental results. The relative wave run-ups on the front face and the back face along the centerline of a cylinder are analyzed. The changes of the relative run-ups with the wave steepness, the relative diameter and the relative depth are studied. It is found that the relative run-ups on the front face and the back face of the cylinder depend mainly on the wave steepness and the relative diameter, while the dependence on the relative depth is weak. The empirical formulae are proposed to calculate the relative run-ups in terms of the wave steepness of incident regular waves and the relative diameter of a cylinder. 展开更多
关键词 STEEP REGULAR wave vertical CYLINDER RUN-UP empirical FORMULA numerical experiments
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Numerical study of clathrin-mediated endocytosis of nanoparticles by cells under tension 被引量:2
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作者 Xinyue Liu Hongwei Yang +2 位作者 Yunqiao Liu Xiaobo Gong Huaxiong Huang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2019年第3期691-701,共11页
In this study, a three-dimensional mathematical model was used to study the contribution of clathrins during the process of cellular uptake of spherical nanoparticles under different membrane tensions. The clathrin-co... In this study, a three-dimensional mathematical model was used to study the contribution of clathrins during the process of cellular uptake of spherical nanoparticles under different membrane tensions. The clathrin-coated pit (CCP) that forms around the inward budding of the cell membrane was modeled as a vesicle with bending rigidity. An optimization algorithm was proposed for minimizing the total energy of the system, which comprises the deforming nanoparticle, receptor-ligand bonds, cell membrane, and CCP, in which way, the profile of the system is acquired. The results showed that the CCP enable full wrapping of the nanoparticles at various membrane tensions. When the cell membrane tension increases, the total deformation energy also increases, but the ratio of CCP bending to the minimum value of the total energy of the system decreases. The results also showed that the diameter of the endocytic vesicles determined by the competition between the stretching of the cell membrane and confinement of the coated pits are much larger than the nanoparticles, which is quit different as the results in passive endocytosis that is not facilitated by the CCPs. The present results indicate that variations of tension on cell membranes constitutes a biophysical marker for understanding the size distribution of CCPs observed in experiments. The present results also suggest that the early abortion of endocytosis is related to that the receptor-ligand bonds cannot generate adequate force to wrap the nanoparticles into the cell membrane before the clathrins respond to support the endocytic vesicles. Correspondingly, late abortion may relate to the inability of CCPs to confine the nanoparticles until the occurrence of the necking stage of endocytosis. 展开更多
关键词 ENDOCYTOSIS Minimum energy method Membrane tension Clathrin-coated PIT Receptor-ligand BOND
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Hydrodynamic Analysis and Power Conversion for Point Absorber WEC with Two Degrees of Freedom Using CFD 被引量:2
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作者 GUO Wei ZHOU Ya-hui +1 位作者 ZHANG Wan-chao ZHAO Qiao-sheng 《China Ocean Engineering》 SCIE EI CSCD 2018年第6期718-729,共12页
Point absorber wave energy device with multiple degrees of freedom(DOF) is assumed to have a better absorption ability of mechanical energy from ocean waves. In this paper, a coaxial symmetric articulated point absorb... Point absorber wave energy device with multiple degrees of freedom(DOF) is assumed to have a better absorption ability of mechanical energy from ocean waves. In this paper, a coaxial symmetric articulated point absorber wave energy converter with two degrees of freedom is presented. The mechanical equations of the oscillation buoy with power take-off mechanism(PTO) in regular waves are established. The three-dimensional numerical wave tank is built in consideration of the buoy motion based upon the CFD method. The appropriate simulation elements are selected for the buoy and wave parameters. The feasibility of the CFD method is verified through the contrast between the numerical simulation results of typical wave conditions and test results. In such case, the buoy with single DOF of heave, pitch and their coupling motion considering free(no PTO damping) and damped oscillations in regular waves are simulated by using the verified CFD method respectively. The hydrodynamic and wave energy conversion characteristics with typical wave conditions are analyzed. The numerical results show that the heave and pitch can affect each other in the buoy coupling motion, hydrodynamic loads, wave energy absorption and flow field.The total capture width ratio with two coupled DOF motion is higher than that with a single DOF motion. The wave energy conversion of a certain DOF motion may be higher than that of the single certain DOF motion even though the wave is at the resonance period. When the wave periods are high enough, the interaction between the coupled DOF motions can be neglected. 展开更多
关键词 CFD simulation wave energy conversion numerical tank coupling motion capture width ratio
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Experimental and numerical investigation of the influence of roughness and turbulence on LUT airfoil performance 被引量:4
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作者 Shoutu Li Ye Li +5 位作者 Congxin Yang Xiaobo Zheng Qing Wang Yin Wang Deshun Li Wenrui Hu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2019年第6期1178-1190,共13页
Vertical-axis wind turbines(VAWTs)have been widely used in urban environments,which contain dust and experience strong turbulence.However,airfoils for VAWTs in urban environments have received considerably less resear... Vertical-axis wind turbines(VAWTs)have been widely used in urban environments,which contain dust and experience strong turbulence.However,airfoils for VAWTs in urban environments have received considerably less research attention than those for horizontal-axis wind turbines(HAWTs).In this study,the sensitivity of a new VAWT airfoil developed at the Lanzhou University of Technology(LUT)to roughness was investigated via a wind tunnel experiment.The results show that the LUT airfoil is less sensitive to roughness at a roughness height of<0.35 mm.Moreover,the drag bucket of the LUT airfoil decreases with increasing roughness height.Furthermore,the loads on the LUT airfoil during dynamic stall were studied at different turbulence intensities using a numerical method at a tip-speed ratio of 2.Before the stall,the turbulence intensity did not considerably affect the normal or tangential force coefficients of the LUT airfoil.However,after the stall,the normal force coefficient varied obviously at low turbulence intensity.Moreover,as the turbulence intensity increased,the normal and tangential force coefficients decreased rapidly,particularly in the downwind region of the VAWT. 展开更多
关键词 AIRFOIL Dynamic load ROUGHNESS Vertical-axis wind turbines(VAWTs) Wind tunnel experiment
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Evolvement of tsunami waves on the continental shelves with gentle slope in the China Seas 被引量:2
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作者 Xi Zhao Hua Liu Benlong Wang 《Theoretical & Applied Mechanics Letters》 CAS 2013年第3期35-39,共5页
Potential tsunami generated in the Okinawa Trench or the Manila Trench may attack the southeast coast of China. The continental shelves with extremely gentle slope in the China Seas affect the evolvement of tsunami wa... Potential tsunami generated in the Okinawa Trench or the Manila Trench may attack the southeast coast of China. The continental shelves with extremely gentle slope in the China Seas affect the evolvement of tsunami waves. In this paper, we carry out the simulation of tsunami propagation based on the fully nonlinear and highly dispersive Boussinesq model, which could describe the nonlinearity and dispersion of water waves quite well. So the undulation characters could be well presented. In terms of the real topographies of the East China Sea and the South China Sea, we take some typical profiles to simulate the hypothetical tsunamis generated in the Okinawa Trench and the Manila Trench. Different waveforms in the near shore regions are obtained. The N-shape tsunami waves will evolve into long wave trains, undular bores or solitons near the coastal area. The numerical results of the near shore waveform provide essential conditions for the further studies of tsunami runup and inundation. 展开更多
关键词 TSUNAMI gentle slope wave train undular bore SOLITON
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A nonlinear model for aerodynamic configuration of wake behind horizontal-axis wind turbine 被引量:2
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作者 Deshun LI Tao GUO +4 位作者 Rennian LI Congxin YANG Zhaoxue CHENG Ye LI Wenrui HU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2019年第9期1313-1326,共14页
Determination of the aerodynamic configuration of wake is the key to analysis and evaluation of the rotor aerodynamic characteristics of a horizontal-axis wind turbine. According to the aerodynamic configuration, the ... Determination of the aerodynamic configuration of wake is the key to analysis and evaluation of the rotor aerodynamic characteristics of a horizontal-axis wind turbine. According to the aerodynamic configuration, the real magnitude and direction of the onflow velocity at the rotor blade can be determined, and subsequently, the aerodynamic force on the rotor can be determined. The commonly employed wake aerodynamic models are of the cylindrical form instead of the actual expanding one. This is because the influence of the radial component of the induced velocity on the wake configuration is neglected. Therefore, this model should be called a "linear model". Using this model means that the induced velocities at the rotor blades and aerodynamic loads on them would be inexact. An approximately accurate approach is proposed in this paper to determine the so-called "nonlinear" wake aerodynamic configuration by means of the potential theory, where the influence of all three coordinate components of the induced velocity on wake aerodynamic configuration is taken into account to obtain a kind of expanding wake that approximately looks like an actual one. First, the rotor aerodynamic model composed of axial (central), bound, and trailing vortexes is established with the help of the finite aspect wing theory. Then, the Biot-Savart formula for the potential flow theory is used to derive a set of integral equations to evaluate the three components of the induced velocity at any point within the wake. The numerical solution to the integral equations is found, and the loci of all elementary trailing vortex filaments behind the rotor are determined thereafter. Finally, to formulate an actual wind turbine rotor, using the nonlinear wake model, the induced velocity everywhere in the wake, especially that at the rotor blade, is obtained in the case of various tip speed ratios and compared with the wake boundary in a neutral atmospheric boundary layer. Hereby, some useful and referential conclusions are offered for the aerodynamic computation and design of the rotor of the horizontal-axis wind turbine. 展开更多
关键词 nonlinear WAKE aerodynamic model vortex-induced VELOCITY INTEGRAL equation of vortex-induced VELOCITY horizontal-axis wind TURBINE
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A Numerical Study of Passive Receptor-Mediated Endocytosis of Nanoparticles:The Effect of Mechanical Properties 被引量:1
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作者 Xinyue Liu Yunqiao Liu +1 位作者 Xiaobo Gong Huaxiong Huang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2018年第8期281-300,共20页
In this work,a three-dimensional axisymmetric model with nanoparticle,receptor-ligand bonds and cell membrane as a system was used to study the quasi-static receptor-mediated endocytosis process of spherical nanoparti... In this work,a three-dimensional axisymmetric model with nanoparticle,receptor-ligand bonds and cell membrane as a system was used to study the quasi-static receptor-mediated endocytosis process of spherical nanoparticles in drug delivery.The minimization of the system energy function was carried out numerically,and the deformations of nanoparticle,receptor-ligand bonds and cell membrane were predicted.Results show that passive endocytosis may fail due to the rupture of receptor-ligand bonds during the wrapping process,and the size and rigidity of nanoparticles affect the total deformation energy and the terminal wrapping stage.Our results suggest that,in addition to the energy requirement,the success of passive endocytosis also depends on the maximum strength of the receptor-ligand bonds. 展开更多
关键词 RECEPTOR-MEDIATED ENDOCYTOSIS NANOPARTICLE UPTAKE optimization method receptor-ligand BONDS drug delivery
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Characteristics of phosphorus adsorption by sediment mineral matrices with different particle sizes 被引量:6
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作者 Yang XIAO Xiao-lian ZHU +3 位作者 Hao-ke CHENG Kai-jie LI Qi LU Dong-fang LIANG 《Water Science and Engineering》 EI CAS CSCD 2013年第3期262-271,共10页
The particle size of sediment is one of the main factors that influence the phosphorus physical adsorption on sediment. In order to eliminate the effect of other components of sediment on the phosphorus physical adsor... The particle size of sediment is one of the main factors that influence the phosphorus physical adsorption on sediment. In order to eliminate the effect of other components of sediment on the phosphorus physical adsorption, the sediment mineral matrices were obtained by removing inorganic matter, metal oxides, and organic matter from natural sediments, which were collected from the Nantong reach of the Yangtze River. The results show that an exponential relationship exists between the median particle size (Ds0) and specific surface area (Sg) of the sediment mineral matrices, and the fine sediment mineral matrix sample has a larger specific surface area and pore volume than the coarse sediment particles. The kinetic equations were used to describe the phosphorus adsorption process of the sediment mineral matrices, including the Elovich equation, quasi-first-order adsorption kinetic equation, and quasi-second-order adsorption kinetic equation. The results show that the quasi-second-order adsorption kinetic equation has the best fitting effect. Using the mass conservation and Langmuir adsorption kinetic equations, a formula was deduced to calculate the equilibrium adsorption capacity of the sediment mineral matrices. The results of this study show that the phosphorus adsorption capacity decreases with the increase of Ds0, indicating that the specific surface area and pore volume are the main factors in determining the phosphorus adsorption capacity of the sediment mineral matrices. This study will help understand the important role of sediment in the transformation of phosphorus in aquatic environments. 展开更多
关键词 sediment mineral matrix particle size specific surface area pore volume phosphorus adsorption
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3D numerical study of tumor blood perfusion and oxygen transport during vascular normalization 被引量:1
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作者 Jie WU Yan CAI +5 位作者 Yi FU Zhujun TAN Ren SUN Shixiong XU Zurong DING Cheng DONG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2015年第2期153-162,共10页
The changes of blood perfusion and oxygen transport in tumors during tumor vascular normalization are studied with 3-dimensional mathematical modeling and numerical simulation. The models of tumor angiogenesis and vas... The changes of blood perfusion and oxygen transport in tumors during tumor vascular normalization are studied with 3-dimensional mathematical modeling and numerical simulation. The models of tumor angiogenesis and vascular-disrupting are used to simulate "un-normalized" and "normalized" vasculatures. A new model combining tumor hemodynamics and oxygen transport is developed. In this model, the intravasculartransvascular-interstitial flow with red blood cell(RBC) delivery is tightly coupled, and the oxygen resource is produced by heterogeneous distribution of hematocrit from the flow simulation. The results show that both tumor blood perfusion and hematocrit in the vessels increase, and the hypoxia microenvironment in the tumor center is greatly improved during vascular normalization. The total oxygen content inside the tumor tissue increases by about 67%, 51%, and 95% for the three approaches of vascular normalization,respectively. The elevation of oxygen concentration in tumors can improve its metabolic environment, and consequently reduce malignancy of tumor cells. It can also enhance radiation and chemotherapeutics to tumors. 展开更多
关键词 tumor hypoxia environment oxygen transport red blood cell(RBC) delivery vascular normalization numerical simulation
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Numerical Study on the Unsteady Characteristics of the Propeller Cavitation in Uniform and Nonuniform Wake Flows 被引量:1
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作者 GONG Zhao-xin CHEN Ying +2 位作者 LI Jie CHEN Xin LU Chuan-jing 《China Ocean Engineering》 SCIE EI CSCD 2020年第5期688-696,共9页
Propeller cavitation is a problematic issue because of its negative effects, such as performances losses, noise,vibration and erosion. Numerical methodology is an effective and efficient technical tool for the study o... Propeller cavitation is a problematic issue because of its negative effects, such as performances losses, noise,vibration and erosion. Numerical methodology is an effective and efficient technical tool for the study of propeller cavitation, however, it is hard to capture tip-vortex cavitation in the previous work by using common turbulence models based on turbulent-viscosity hypothesis. In this work, the Reynolds-Averaged Naiver-Stokes(RANS)approach, adopting the Reynolds stress turbulence model(RSM), is taken to study the unsteady characteristics of the cavitation on the four-bladed INSEAN E779 A model propeller. The numerical simulation was carried out using the commercial CFD software ANSYS Fluent 14.0. One kind of uniform wake flow and two kinds of nonuniform wake flows are considered here. The results in the uniform flow show a good agreement with previous experimental results on both the sheet cavitation and the tip vortex cavitation and prove the ability of the RSM on capturing the tip vortex cavitation. Two kinds of nonuniform wake flows are designed based on the previous experimental researches and the unsteady characteristics of the propeller cavitation are analyzed by comparing the results in the uniform and two nonuniform wake flows together. 展开更多
关键词 propeller cavitation wake flow Reynolds stress model
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Numerical Simulation of Blood Flow in Aorta with Dilation:A Comparison between Laminar and LES Modeling Methods 被引量:1
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作者 Lijian Xu Tianyang Yang +3 位作者 Lekang Yin Ye Kong Yuri Vassilevski Fuyou Liang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2020年第8期509-526,共18页
Computational modeling methods have been increasingly employed to quantify aortic hemodynamic parameters that are challenging to in vivo measurements but important for the diagnosis/treatment of aortic disease.Althoug... Computational modeling methods have been increasingly employed to quantify aortic hemodynamic parameters that are challenging to in vivo measurements but important for the diagnosis/treatment of aortic disease.Although the presence of turbulence-like behaviors of blood flow in normal or diseased aorta has long been confirmed,the majority of existing computational model studies adopted the laminar flow assumption(LFA)in the treatment of sub-grid flow variables.So far,it remains unclear whether LFA would significantly compromise the reliability of hemodynamic simulation.In the present study,we addressed the issue in the context of a specific aortopathy,namely aortic dilation,which is usually accompanied by disturbed flow patterns.Three patient-specific aortas with treated/untreated dilation of the ascending segment were investigated,and their geometrical models were reconstructed from computed tomography angiographic images,with the boundary conditions being prescribed based on flow velocity information measured in vivo with the phase contrast magnetic resonance imaging technique.For the modeling of blood flow,apart from the traditional LFA-based method in which sub-grid flow dynamics is ignored,the large eddy simulation(LES)method capable of incorporating the dissipative energy loss induced by turbulent eddies at the sub-grid level,was adopted and taken as a reference for examining the performance of the LFA-based method.Obtained results showed that the simulated large-scale flow patterns with the two methods had high similarity,both agreeing well with in vivo measurements,although locally large between-method discrepancies in computed hemodynamic quantities existed in regions with high intensity of flow turbulence.Quantitatively,a switch from the LES to the LFAbased modeling method led to mild(<6%)changes in computed space-averaged wall shear stress metrics(i.e.,SA-TAWSS,SA-OSI)in the ascending aortic segment where intensive vortex evolution accompanied by high statistical Reynolds stress was observed.In addition,comparisons among the three aortas revealed that the treatment status of aortic dilation or the concomitant presence of aortic valve disease,despite its remarkable influence on flow patterns in the ascending aortic segment,did not significantly affect the degrees of discrepancies between the two modeling methods in predicting SA-TAWSS and SA-OSI.These findings suggest that aortic dilation per se does not induce strong flow turbulence that substantially negates the validity of LFA-based modeling,especially in simulating macro-scale hemodynamic features. 展开更多
关键词 Blood flow aortic dilation computational modeling turbulence laminar flow assumption large eddy simulation
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Effects of laser power density on static and dynamic mechanical properties of dissimilar stainless steel welded joints 被引量:1
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作者 Yan-Peng Wei Mao-Hui Li +3 位作者 Gang Yu Xian-Qian Wu Chen-Guang Huang Zhu-Ping Duan 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第5期1334-1339,共6页
The mechanical properties of laser welded joints under impact loadings such as explosion and car crash etc. are critical for the engineering designs. The hardness, static and dynamic mechanical properties of AISI304 a... The mechanical properties of laser welded joints under impact loadings such as explosion and car crash etc. are critical for the engineering designs. The hardness, static and dynamic mechanical properties of AISI304 and AISI316L dissimilar stainless steel welded joints by CO2 laser were experimentally studied. The dynamic strainstress curves at the strain rate around 103 s-1 were obtained by the split Hopkinson tensile bar (SHTB). The static mechanical properties of the welded joints have little changes with the laser power density and all fracture occurs at 316 L side. However, the strain rate sensitivity has a strong depen- dence on laser power density. The value of strain rate factor decreases with the increase of laser power density. The welded joint which may be applied for the impact loading can be obtained by reducing the laser power density in the case of welding quality assurance. 展开更多
关键词 Laser welding Dynamic mechanics Strain rate.Power density
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