Molecular dynamics (MD) simulation is used to study slip at the fluid-solid boundary in an unsteady flow based on the Stokes’ second problem. An increase in slip is observed in comparison to the steady flow for shear rates below the critical shear rate of the corresponding steady flow. This increased slip is attributed to fluid inertial forces not represented in a steady flow. An unsteady mathe...

Abstract: The structure of natural tornadoes and simulated analogs are sensitive to the lower boundary condition for friction. Three-dimensional numerical simulations of storms require a choice for turbulence parameterizations and resolution of wind near the lower boundary. This article explores some of the consequences of choices of a surface drag coefficient on the structure of a mature simul...

Based on the no-slip boundary condition for walls at rest for the lattice Boltzmann Bathnagar-Gross-Krook method by J.C.G. Verschaeve [10], a no-slip boundary condition for walls with a tangential movement is derived. Numerical tests verify that the present boundary condition is second order accurate and stable for relaxation frequencies close to two.

Many types of micro-electro-mechanical-system (MEMS) based products are currently employed in a variety of applications. However, high friction in these systems is a problem which limits the development of MEMS devices in which sliding contacts are involved. The aim of this research is to evaluate the effect of boundary slip on the hydrodynamic friction in a low load lubricated MEMS, in particu...

The transient hydrodynamics and thermal behaviors of fluid flow in open-ended vertical parallel-plate porous microchannel are investigated semi-analytically under the effect of the hyperbolic heat conduction model. The model that combines both the continuum approach and the possibility of slip at the boundary is adopted in the study. The Effects of Knudsen number , Darcy number , and thermal re...

A general adsorption model is developed to describe the interactions between near-wall fluid molecules and solid surfaces. This model serves as a framework for the theoretical modelling of boundary slip phenomena. Based on this adsorption model, a new general model for the slip velocity of fluids on solid surfaces is introduced. The slip boundary condition at a fluid-solid interface has hithert...

In the present study, a compact analytical model is developed to determine the pressure drop of fully-developed, incompressible, and constant properties slip-flow through arbitrary cross-section microchannels. An averaged firstorder Maxwell slip boundary condition is considered. Introducing a relative velocity, the difference between the bulk flow and the boundary velocities, the axial momentum...

We consider the free fall of a sphere above a wall in a viscous incompressible fluid. Weinvestigate the influence of boundary conditions on the finite-time occurrence of contactbetween the sphere and the wall. We prove that slip boundary conditions enable tocircumvent the ”no-collision” paradox associated with no-slip boundary conditions. Wealso examine the case of mixed bou...

a lattice boltzmann method is applied to demonstrate the comparison results of simulating natural convection in an open end cavity using different hydrodynamic and thermal boundary conditions. the prandtl number in the present simulation is 0.71, rayleigh numbers are 104,105 and 106 and viscosities are selected 0.02 and 0.05. on-grid bounce-back method with first-order accuracy and non-slip met...

The flow and heat transfer of an electrically conducting non-Newtonian second grade fluid due to a radially stretching surface with partial slip is considered. The partial slip is controlled by a dimensionless slip factor, which varies between zero (total adhesion) and infinity (full slip). Suitable similarity transformations are used to reduce the resulting highly nonlinear partial differentia...