Zhaosheng Yu

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Verified

Zhaosheng verified their affiliation via an institutional email.

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• PhD
• Professor (Full) at Zhejiang University

We experimentally investigate the finite-size spherical particle migration in micro-rectangular channels in a Newtonian fluid (22 wt. % glycerol aqueous solution) and a viscoelastic fluid (8 wt. % polyvinylpyrrolidone aqueous solution) at various particle size to hydraulic diameter ratios a/Dh and channel aspect ratios H/W. Experiments are performe...

The hydrodynamic behaviours of finite-size microorganisms in turbulent channel flows are investigated using a direct-forcing fictitious domain method. The classical ‘squirmer’ model, characterized by self-propulsion through tangential surface waves at its boundaries, is employed to mimic the swimming microorganisms. We adopt various simulation para...

Granular materials transition between unjammed (deformable) and jammed (rigid) states when adjusting their packing density. Here, we report on experiments demonstrating that the same kind of phase transition can be alternatively achieved through temperature-controlled particle shape change. Using a confined system of randomly-packed rod-like partic...

Microorganisms or man-made microswimmers swimming near obstacles have been investigated intensively owing to their importance in biology, physiology, and biomedical engineering. In this work, a direct-forcing fictitious domain method is...

The ways in which microorganisms behave in their confined environment remain unclear. To understand the dynamics of microorganisms swimming in geometric confinement, a fictitious domain method is applied to study the collective motions of squirmers in viscoelastic fluids confined by circular chambers at low Reynolds numbers. It is observed that bot...

A new immersed boundary method is proposed for the numerical simulation of the melting of solid particles in its own liquid at a high temperature. The main feature of the new method is the use of the modified direct-forcing immersed boundary method for the solution of the flow field and the sharp-interface immersed boundary method for the temperatu...

Interface-resolved direct numerical simulations (DNS) of clustered settling suspensions in a periodic domain are performed to study the filtered drag force for clustered particle-laden flows. Our results show that, for the homogeneous system, the filtered drag is independent of the filter size, whereas for the clustered particle-laden flows, the av...

The elasto-inertial focusing and rotating characteristics of spheroids in a square channel flow of Oldroyd-B viscoelastic fluids are studied by the direct forcing/fictitious domain method. The rotational behaviours, changes in the equilibrium positions and travel distances are explored to analyse the mechanisms of spheroid migration in viscoelastic...

In this study, a new criterion for the splashing of a droplet on a dry smooth surface is established from high-fidelity numerical simulations. The new criterion involves the Weber number, Reynolds number and contact angle. A new splashing mode, termed spreading splashing, is proposed, which predominates for contact angles below 120 degrees. For con...

We numerically investigate the hydrodynamic interactions between two microswimmers in viscoelastic fluids at low Reynolds number regimes using the fictitious domain method. In the Newtonian fluid, after contact, pushers rotate toward each other and remain in a “trapped” state for a long time, induced by a counterclockwise viscous torque. We believe...

Multigrain/polydispersity has a significant impact on turbidity current (TC). Despite the fact that several researches have looked into this effect, the impact of the fluid–particle interactions is not fully understood. Motivated by this, we employ the Eulerian–Lagrangian computational fluid dynamics–discrete element method model to investigate the...

In the present work, a three-dimensional fictitious domain method for particulate flows with heat transfer is proposed. For the case of fixed particle temperature, an iterative scheme for the temperature Lagrange multiplier is proposed, in order to determine its initial value and overcome the spurious oscillation of the explicit scheme at the initi...

The sedimentation of two spherical solid objects in a viscous fluid has been extensively investigated and well understood. However, a pair of flat disks (in three dimensions) settling in the fluid shows more complex hydrodynamic behaviour. The present work aims to improve the understanding of this phenomenon by performing direct numerical simulatio...

Granular materials exhibit unique secondary flow behaviors upon shearing. We demonstrate, using particle dynamics simulations, that the secondary flow patterns are controlled by a pressure exerted on particle bed. A threshold pressure, at which vortex flow transitions to disturbed or chaotic flow, depends on particle shape, that influences interpar...

We numerically investigate the hydrodynamics of a spherical swimmer carrying a rigid cargo in a Newtonian fluid. This swimmer model, a ‘squirmer’, which is self-propelled by generating tangential surface waves, is simulated by a direct-forcing fictitious domain method (DF-FDM). We consider the effects of swimming Reynolds numbers ( Re ) (based on t...

Clustering of flexible fibers in riser flows is investigated using a hybrid approach of Discrete Element Method and Computational Fluid Dynamics. Unlike spherical particles, the flexible fibers possess elongated shape, undergo significant deformation, and dissipate kinetic energies through rapid fiber deformation. The present studies show that thes...

The turbidity current (TC), a ubiquitous fluid–particle coupled phenomenon in the natural environment and engineering, can transport over long distances on an inclined terrain due to the suspension mechanism. A large-eddy simulation and discrete element method coupled model is employed to simulate the particle-laden gravity currents over the inclin...

Correlations for the interfacial terms in the fluid dissipation rate equation and Reynolds stress equations are established for particle-laden flows, based on data from the interfaced-resolved direct numerical simulations of particle sedimentation in a periodic domain at a density ratio ranging from 0.01 to 1000, a particle concentration ranging fr...

Pair of particle chain self-organization in a square channel flow of Giesekus viscoelastic fluid is studied by the direct forcing/fictitious domain method. The effects of particle diameter, initial particle distance, shear-thinning ( n), Weissenberg number ( Wi), and Reynolds number ( Re) are explored to analyze the mechanism of particle chain self...

Microorganisms can efficiently navigate in anisotropic complex fluids, but the precise swimming mechanisms remain largely unexplored. Their dynamics is determined by the interplay between multiple effects, including the fluid's orientation order, swimmer's undulatory gait and the finite length. Here, we extend the numerical study of the two-dimensi...

Clustering of flexible fibers in riser flows is investigated using a hybrid approach of Discrete Element Method and Computational Fluid Dynamics. Unlike spherical particles, the flexible fibers possess elongated shape, undergo significant deformation, and dissipate kinetic energies through rapid fiber deformation. The present studies show that thes...

Chemokine receptor CXCR4 plays a crucial role in leukocyte recruitment and inflammation regulation to influence tissue repair in ischemic diseases. Here we assessed the effect of CXCR4 expression in macrophages on angiogenesis in the ischemic hindlimb of a mouse. Inflammatory cells were increased in the ischemic muscles of hindlimb, and CXCR4 was h...

In this paper we demonstrate that the original Troshko-Hassan model with the correction coefficient being unity should be chosen for the interfacial term in the turbulent kinetic energy equation at the statistically steady state, based on theoretical analysis and interface-resolved direct numerical simulations of the particle sedimentation in a per...

Granular materials exhibit unique secondary flow behaviors upon shearing. We demonstrate, using particle dynamics simulations, that the secondary flow patterns are controlled by a pressure exerted on the particle bed. The threshold pressure, at which vortex flow transitions to disturbed or chaotic flow, depends on particle shape, that influences in...

A drag correlation is established for laminar particle-laden flows, based on data from the interfaced-resolved direct numerical simulations (IR-DNS) of particle sedimentation in a periodic domain at density ratio ranging from 2 to 1000, particle concentration ranging from 0.59 % to 14.16 %, and particle Reynolds number below 132. Our drag decreases...

We study the hydrodynamics of a spherical and dumbbell-shaped microswimmer in a tube. Combined with a squirmer model generating tangential surface waves for self-propulsion, a direct-forcing fictitious domain method is employed to simulate the swimming of the microswimmers. We perform the simulations by considering the variations of the swimming Re...

A turbulent channel flow of a binary mixture of finite-size neutrally-buoyant ellipsoidal particles is studied by using a parallel direct-forcing fictitious domain method at friction Reynolds number of 180 and the particle aspect ratios of 1/3 (oblate particle) and 4 (prolate particle) respectively. The total particle volume fraction is fixed at 14...

A hybrid smoothed particle hydrodynamics (SPH) coupled to a direct-forcing fictitious domain (FD) scheme is proposed for the simulation of particulate flows. The new method is effective in calculating the particle-fluid interaction forces and uses a kernel interpolation function to realize the momentum exchange between fluids and particles. A highe...

The migration of polydisperse particles and the formation of self-organized particle chains in a square channel flow of non-Newtonian fluids is studied. The effects of rheological behaviour of the fluid, solution concentration and flow rate are explored experimentally. The direct forcing/fictitious domain method is adopted to qualitatively verify t...

Deterministic lateral displacement (DLD) is a popular technique for separating micro-scale and nano-scale particles continuously. In this paper, an efficient three-dimensional fictitious domain method is developed for the direct numerical simulation of the motion of a non-colloidal spherical particle in the DLD device (i.e., cylinder array), based...

Rationale: Heart failure with preserved ejection fraction (HFpEF) can arise from hypertension‐induced cardiac remodeling. Monocyte/macrophage accumulation and inflammation are crucial elements in the pathogenesis of hypertension-induced cardiac remodeling. The C-X-C chemokine receptor 4 (CXCR4) is a critical regulator of the macrophage-mediated imm...

The migration of ellipsoidal particles in bounded shear flow of Giesekus fluids is studied numerically using the direct forcing/fictitious domain method for the Weissenberg number ranging from 0.1 to 3.0, the mobility parameter α which quantifies the shear-thinning effect ranging from 0.1 to 0.7. The model and numerical method are validated by comp...

Three-dimensional simulations of polydisperse shear flows of rod and disk mixtures are performed using the discrete element method. The effects of particle shape distribution on flow behaviors are investigated assuming that all particles have the same volume and density but different shapes in the simulations. The solid phase stresses and bulk fric...

Interface-resolved direct numerical simulations of downward particle-laden turbulent channel flows are performed by using a direct-forcing fictitious domain method. The effects of the particle settling coefficient, the density ratio (2, 10, and 100), and the particle size on fluid-turbulence interactions are investigated at a bulk Reynolds number o...

Gas-fluidized beds of flexible fibres, which have been rarely studied before, are investigated in this work using the coupled approach of the discrete element method and computational fluid dynamics. In the present numerical method, gas–fibre interaction is modelled by calculating the interaction force for each constituent element in the fibre, and...

The effects of the particle collision model in a direct-forcing fictitious domain method on the fluid and particle statistics of a fully developed turbulent channel flow laden with finite-size neutrally buoyant particles are numerically investigated. The particle collisions are described by a combination of the discrete element method and the lubri...

Particle migration and trajectory patterns in a confined simple shear-flow of Giesekus viscoelastic fluid are studied numerically using the direct forcing/fictitious domain method with Reynolds number, Re, from 0.1 to 50, Weissenberg number, Wi, from 0.1 to 1.0, and ratio of solvent viscosity to total viscosity at 0.3. The method is validated by co...

Interface-resolved direct numerical simulations of the interactions between spheroidal particles and upward vertical turbulent channel flows - Volume 891 - Chenlin Zhu, Zhaosheng Yu, Dingyi Pan, Xueming Shao

The effects of particle shape differences on binary mixture shear flows are investigated using the Discrete Element Method (DEM). The binary mixtures consist of frictionless rods and disks, which have the same volume but significantly different shapes. In the shear flows, stacking structures of rods and disks are formed. The effects of the composit...

Interface-resolved numerical simulations of particle-laden turbulent flows in a vertical channel filled with Bingham fluids - Volume 883 - Chenlin Zhu, Zhaosheng Yu, Xueming Shao, Jian Deng

Interface-resolved simulations of particle-laden turbulent channel flows with spanwise rotation at a Reynolds number of 180 and different rotation numbers ranging from 0.1 to 1.0 are performed with a fictitious domain method. The difficulty of the centrifugal force on the particles not satisfying the periodic boundary condition is circumvented by t...

The lateral migration of a spherical particle in a sheared Giesekus fluid is numerically studied by the direct-forcing fictitious domain method. The model is first validated by comparing the simulation results with the available data in the literature. Effects of the viscosity ratio, shear thinning, Weissenberg number, and wall confinement on the p...

The motion of neutrally buoyant ellipsoids in a planar Couette flow of Giesekus viscoelastic fluids between two narrowly set plates is numerically simulated with a fictitious domain method. The aspect ratio of the ellipsoid is 4 (i.e., prolate spheroids) and the Deborah number (De) ranges from 0 to 4.0. For a single ellipsoid initially placed in th...

In this paper, the lateral migration of a neutrally buoyant spherical particle in the pressure-driven rectangular channel flow of an Oldroyd-B fluid is numerically investigated with a fictitious domain method. The aspect ratio of the channel cross-section considered is 1 and 2, respectively. The particle lateral motion trajectories are shown for th...

A multiphase smoothed particle hydrodynamics (SPH) model was established to study the boiling phenomenon of a water film heated on a hydrophilic or hydrophobic surface. For the two-phase fluids of water vapor and liquid with continuous density gradient, conservation equations in Lagrangian formulation were discretized by SPH fluid particles. While...

A direct-forcing fictitious domain (DFFD) method is used to perform fully resolved numerical simulations of turbulent channel flows laden with large neutrally buoyant particles. The effects of the particles on the turbulence (including the mean velocity, the root mean square (RMS) of the velocity fluctuation, the probability density function (PDF)...

A parallel direct-forcing fictitious domain method is employed to perform interface-resolved numerical simulations of the interactions between neutrally buoyant finite-size spheroidal particles and turbulent channel flows. The effects of the aspect ratio of the spheroidal particles on the turbulence modulation and the rotation of the particles are...

The transport of finite-size particles in a turbulent plane Couette flow has been studied by particle-resolved numerical simulations based on the Force Coupling Method. The influence of the deviation of particle shape from sphericity was addressed, using neutrally buoyant spheroids with aspect ratio ranging from 0.5 to 2. The particle transport was...

In this paper, the lateral migration of a neutrally buoyant spherical particle in a pressure-driven rectangular-shaped channel flow of Giesekus viscoelastic fluids is numerically investigated with a fictitious domain method. The particle trajectories are shown for the channel aspect ratio 2, the ratio of the particle diameter to the channel height...

Interface-resolved direct numerical simulations of the particle-laden turbulent flows in a square duct are performed with a direct-forcing fictitious domain method. The effects of the finite-size particles on the mean and root-mean-square (RMS) velocities are investigated at the friction Reynolds number of 150 (based on the friction velocity and ha...

A parallel direct-forcing fictitious domain method is employed to perform fully resolved numerical simulations of turbulent channel flow laden with finite-size particles. The effects of the particle-fluid density ratio on the turbulence modulation in the channel flow are investigated at the friction Reynolds number of 180, the particle volume fract...

A parallel direct-forcing fictitious domain method is applied in fully-resolved numerical simulations of particle-laden turbulent flows in a square duct. The effects of finite-size heavy particles on the mean secondary flow, the mean streamwise velocity, the root-mean-square velocity fluctuation, and the particle concentration distribution are inve...

Choanoid fluidized bed bioreactors (CFBBs) are newly developed core devices used in bioartificial liver-support systems to detoxify blood plasma of patients with microencapsulated liver cells. Direct numerical simulations (DNS) with a direct-forcing/fictitious domain (DF/FD) method were conducted to study the hydrodynamic performance of a CFBB. The...

The direct-forcing fictitious domain method is extended to simulate the locomotion of a passively pitching foil. Our study focuses on the hysteresis phenomenon that the critical frequency for the reverse of the locomotion direction of the wing in case of decreasing frequency is smaller than that in case of increasing frequency. In our simulations,...

A 2D numerical simulation of fluid-structure interactions in the propulsion of a biomimetic jellyfish is conducted with the fictitious domain method. The effects of the fluid dynamics viscosity and the elastic modulus of the medusa on the swimming motion are investigated. The results indicate that the propulsion of the jellyfish is significantly af...

A direct-forcing fictitious domain method is employed to study the dynamics of an open triangle in a vertically oscillatory flow. The flow structures, the vertical force and the torque on the fixed body are analysed for the stable flow regime in which the flow structures form and evolve exactly in the same way in each period and the unstable regime...

A parallel direct-forcing (DF) fictitious domain (FD) method for the simulation of particulate flows is reported in this paper. The parallel computing strategies for the solution of flow fields and particularly the distributed Lagrange multiplier are presented, and the high efficiency of the parallel code is demonstrated. The new code is then appli...

A fully mesoscopic, multiple-relaxation-time (MRT) lattice Boltzmann method (LBM) is developed to perform particle-resolved direct numerical simulation (DNS) of wall-bounded turbulent particle-laden flows. The fluid-solid particle interfaces are treated as sharp interfaces with no-slip and no-penetration conditions. The force and torque acting on a...

Deterministic lateral displacement (DLD) technology is a newly developed method which can separate microscale and nanoscale particles continuously and efficiently. In this paper, a direct numerical simulation method (i.e. a fictitious domain method) is used to simulate the motion of an elastic particle (modelled as homogeneously elastic body) in th...

The orientation of a cone settling in a vertical duct has been numerically investigated by using the direct-forcing fictitious domain method. Our results indicate that with the characteristic Reynolds number Re being 30, the cone settles with apex pointing upward if the cone apex angle is smaller than 48°, irrespective of the initial orientation. F...

The effects of large neutrally buoyant particles on the flow instability and turbulence transition in pipe flow are investigated with the fictitious domain method. The periodic boundary condition is introduced in the streamwise direction. The work comprises two parts. In the first part, the pressure gradient is kept constant, and the purpose is to...

A direct-forcing fictitious domain method was employed to perform fully-resolved numerical simulations of turbulent channel flow laden with large neutrally buoyant particles. The effects of the particles on the turbulence at the friction Reynolds number of 180 were investigated. The particle volume fractions are 0.79% and 2.36%, respectively. Resul...

The structure of porous media was approximated by distributing solid particles in the cavity to study the heat transfer of natural convection in square porous media. And the fictitious domain method is used to resolve the equations of velocity and temperature. The influences of the particles' number, distributing pattern and shape on heat transfer...

A fictitious domain method is used to perform fully resolved numerical simulations of particle-laden turbulent flow in a horizontal channel. The effects of large particles of diameter 0.05 and 0.1 times the channel height on the turbulence statistics and structures are investigated for different settling coefficients and volume fractions (0.79 %–7....

In this paper, we combine the direct-forcing fictitious domain (DF/FD) method and the sharp interface method (SI) to resolve the problem of particle dielectrophoresis in three dimensions. The flow field is solved with the DF/FD method. The electric field governed by a Laplace equation with a jump coefficient across the particle surface is solved wi...

In this article, we employ a fully-resolved numerical simulation method (the fictitious domain method) to investigate the effects of large neutrally-buoyant particles on the turbulent flow in a pipe at low Reynolds number and non-dilute regimes. The tube Reynolds number is fixed to be 4 900, the particle-pipe diameter ratio is 0.1, and the particle...

The hydrodynamic performances of a fishlike undulating foil in the wake of a D-section cylinder are numerically investigated by using a modified immersed boundary method. The results regarding the effects of various controlling parameters, including the distance between the foil and the D-cylinder, the frequency and the phase angle of foil’s undula...

The Distributed-Lagrange-Multiplier based Fictitious Domain (DLM/FD) method previously proposed by Yu [J. Comput. Phys. 207 (2005), 1-27] for the simulation of fluid/flexible-body interaction problems is extended from the 2D to the 3D case in this study. We first demonstrate that the Lagrange multiplier problem can be more efficiently solved with a...

In this paper, we combine the direct-forcing fictitious domain (DF/FD) method and the sharp interface method to resolve the problem of particle dielectrophoresis in two dimensions. The flow field and the motion of particles are solved with the DF/FD method, the electric field is solved with the sharp interface method, and the electrostatic force on...

An immersed-boundary method is used to investigate the flapping wings with different aspect ratios ranging from 1 to 5. The numerical results on wake structures and the performance of the propulsion are given. Unlike the case of the two-dimensional flapping foil, the wing-tip vortices appear for the flow past a three-dimensional flapping wing, whic...

The flow in a finite diverging channel opening into a large space and resembling the experimental prototype of Putkaradze and Vorobieff (2006) was numerically investigated. The effects of the Reynolds number, initial condition, intersection angle, length of the wedge edges, and the outer boundary condition were examined. The numerical results showe...

The inertial migration of a single neutrally buoyant circular particle in both nonoscillatory and oscillatory pressure-driven flows in a two-dimensional (2D) channel at moderately high Reynolds numbers has been numerically investigated by using the direct-forcing fictitious domain (DF/FD) method. In both nonoscillatory and oscillatory cases, there...

The inertial migration of spherical particles in a circular Poiseuille flow is numerically investigated for the tube Reynolds number up to 2200. The periodic boundary condition is imposed in the streamwise direction. The equilibrium positions, the migration velocity, and the angular velocity of a single particle in a tube cell are examined at diffe...

A direct-forcing fictitious domain (DF/FD) method for the simulation of particulate flows is reported. The new method is a non-Lagrange-multiplier version of our previous DLM/FD code and is obtained by employing a discrete δ-function in the form of bi(tri-) function to transfer explicitly quantities between the Eulerian and Lagrangian nodes, as in...

In this study, the hydrodynamic interactions between two tandem foils undergoing fishlike swimming motion are investigated numerically by solving the Navier-Stokes equations with the immersed-boundary method. The two foils represent two tandem propellers attached on a concept ship. The thrusts and efficiencies at three typical Strouhal numbers, i.e...