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  • Evolution of windblown sand flux and dune field——Trans-scale modeling and simulation
  • Windblown sand flux and dune field evolving toward the oasis have been a common ecological and environmental threat confronted by many countries.Meanwhile,it is also a kind of complex dynamical process involving multiple temporal and spatial scales which is still out of accurate description through current field observations.Available models and reliable quantitative simulations are of significant value to predict the spreading rate of desertification and provide an optimal design for sand prevention.This p...
  • Surface effect on Bleustein-Gulyaev wave in a piezoelectric half-space
  • Surface effect,which is attributed to the different environment surrounding the surface or near-surface atoms from that embracing the bulk atoms,may become significant when the surface-to-volume ratio of a body is large.This paper considers the effect of a plane boundary of a piezoelectric body modeled as a thin layer with specified material properties,for which a transfer relation between the state vectors at the top and bottom surfaces is derived based on the state-space formulations.The equations of surf...
  • Competing failure mechanisms of thin metal films on polymer substrates under tension
  • The ductility of thin metal films on polymer substrates reported in recent experiments has a huge disparity,ranging from less than 1 % up to more than 50 %.To reveal the underpinning origins for such a large variation,this paper reports a systematic computational study of two competing failure mechanisms:metal film necking and grain boundary cracking.The quantitative results suggest that strong grain boundaries and metal/polymer interfacial adhesion are keys to achieve high ductility of polymer-supported me...
  • A statistical mechanics model of carbon nanotube macro-films
  • Carbon nanotube macro-films are two-dimensional films with micrometer thickness and centimeter by centimeter in-plane dimension.These carbon nanotube macroscopic assemblies have attracted significant attention from the material and mechanics communities recently because they can be easily handled and tailored to meet specific engineering needs.This paper reports the experimental methods on the preparation and characterization of single-walled carbon nanotube macro-films,and a statistical mechanics model on ...
  • Assessment of the modulated gradient model in decaying isotropic turbulence
  • A recently introduced nonlinear model undergoes evaluations based on two isotropic turbulent cases:a University of Wiscosion-Madison case at a moderate Reynolds number and a Johns Hopkins University case at a high Reynolds number.The model uses an estimation of the subgrid-scale(SGS) kinetic energy to model the magnitude of the SGS stress tensor,and uses the normalized velocity gradient tensor to model the structure of the SGS stress tensor.Testing is performed for the first case through a comparison betwee...
  • Numerical investigation on the position of holes for reducing stress concentration in composite plates with bolted and riveted joints
  • This paper studies the effects of fiber orientaion and holes position on stress concentration and the determination of weakened areas in the composite of glass fiber reinforced epoxy resin around the hole for joints by using the finite element method.In this study,for the observation of areas affected by stress concentration Tsai-Wu failure criterion is used to determine the failed elements and ANSYS Software is implemented for modeling.In order to compare the effect of geometric parameters on stress concen...
  • A theoretical model of collision between soft-spheres with Hertz elastic loading and nonlinear plastic unloading
  • This paper presents a theoretical model on the normal(head-on) collision between soft-spheres on the basis of elastic loading of the Hertz contact for compression process and a nonlinear plastic unloading for restitution one,in which the parameters all are determined in terms of the material and geometric ones of the spheres,and the behaviors of perfect elastic,inelastic,and perfect plastic collisions appeared in the classical mechanics are fully described once a value of coefficient of restitution is speci...
  • Band-pass filtered velocity statistics in decaying turbulent box
  • For homogeneous isotropic turbulence study,the acquisition of band-pass filtered velocity increments(FVI) in a non-forced turbulent box is still a challenge both experimentally and numerically.Turbulence and associated physical processes,at a given instant,are permanently contaminated by a forcing process which can seldom be universal.The situation tends to be the origin of intermittency and the non-Gaussian probability density distribution for acceleration and velocity gradients.To reveal implied mechanism...
  • A typhoon-like vortex solution of incompressible 3D inviscid flow
  • This letter obtains a typhoon-like vortex solution by solving the Bragg-Hawthorne equation.The solution describes spiral paths of fluid material element on the Bernoulli surface,whereas some new exact solutions are obtained which are bounded in the whole region.The first one is a continued umbrella vortex solution,which is a typhoon-like vortex.The second one is a multi-planar solution,which is periodic in z-coordinate.Within each layer,there is an umbrella vortex solution similar to the first one.The above...
  • Convective stability analysis of a micropolar fluid layer by variational method
  • This paper studies Rayleigh-B‘enard convection of micropolar fluid layer heated from below with realistic boundary conditions.A specific approach for stability analysis of a convective problem based on variational principle is applied to characterize the Rayleigh number for quite general nature of bounding surfaces.The analysis consists of replacing the set of field equations by a variational principle and the expressions for Rayleigh number are then obtained by using trial function satisfying the essential...
  • Unsteady hydromagnetic Couette flow through a porous medium in a rotating system
  • This paper investigates the unsteady hydromagnetic Couette fluid flow through a porous medium between two infinite horizontal plates induced by the non-torsional oscillations of one of the plates in a rotating system using boundary layer approximation.The fluid is assumed to be Newtonian and incompressible.Laplace transform technique is adopted to obtain a unified solution of the velocity fields.Such a flow model is of great interest,not only for its theoretical significance,but also for its wide applicatio...
  • Lagrangian formulation of continuum with internal long-range interactions
  • Based on a new definition of nonlocal variable,this paper establishes the Lagrangian formulation for continuum with internal long-range interactions.Distinguished from the existing theories,the nonlocal term in the Lagrangian formulation automatically satisfies the zero mean condition determined by the action and reaction law.By this formulation,elastic wave in a rod with the internal long-range interactions is investigated.The dispersion of the elastic wave is predicted.
  • Mixed convection effects on heat and mass transfer in a non Newtonian fluid with chemical reaction over a vertical plate
  • This paper studies mixed convection,double dispersion and chemical reaction effects on heat and mass transfer in a non-Darcy non-Newtonian fluid over a vertical surface in a porous medium under the constant temperature and concentration.The governing boundary layer equations,namely,momentum,energy and concentration,are converted to ordinary differential equations by introducing similarity variables and then are solved numerically by means of fourth-order Runge-Kutta method coupled with double-shooting techn...
  • Vibration and stability of an aircraft tail under simultaneous primary-combined and internal resonance
  • This paper adds a negative velocity feedback to the dynamical system of twin-tail aircraft to suppress the vibration.The system is represented by two coupled second-order nonlinear differential equations having both quadratic and cubic nonlinearities.The system describes the vibration of an aircraft tail subjected to both multi-harmonic and multi-tuned excitations.The method of multiple time scale perturbation is adopted to solve the nonlinear differential equations and obtain approximate solutions up to th...
  • Simulation of bacterial flagellar phase transition by non-convex and non-local continuum modeling
  • Bacterial flagellar filament can undergo a stress-induced polymorphic phase transition in both vitro and vivo environments.The filament has 12 different helical forms(phases) characterized by different pitch lengths and helix radii.When subjected to the frictional force of flowing fluid,the filament changes between a left-handed normal phase and a right-handed semi-coiled phase via phase nucleation and growth.This paper develops non-local finite element method(FEM) to simulate the phase transition under a d...
  • Coupled modeling of tumour angiogenesis, tumour growth,and blood perfusion
  • This paper proposes a more realistic mathematical simulation method to investigate the dynamic process of tumour angio-genesis by fully coupling the vessel growth,tumour growth and associated blood perfusion.The tumour growth and angiogenesis are coupled by the chemical microenvironment and the cell-matrix interaction.The haemodynamic calculation is carried out on the new vasculature,and an estimation of vessel collapse is made according to the wall shear stress criterion.The results are consistent with phy...
  • 《力学快报:英文版》封面

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