mixed convection of al 2 o 3 -water nanofluid in a square microcavity is investigated numerically. governing equations are discretized and solved using the finite volume method and simpler algorithm. the knudsen number is selected between 0.001 and 0.1 to consider slip velocity and the jump temperature boundary conditions. results showed that nusselt number is a function of richardson number, k...

In this work, slip flow of helium gas has been studied in a three dimensional rectangular microchannel heat sink with 11 microchannel and 10 rectangular fins. Helium gas flow is considered ideal and incompressible. The finite volume method with using coupled algorithm is employed to carry out the computation. To validate the present work, comparison with numerical and experimental studies is do...

micro scale gas flows has attracted significant research interest in the last two decades. in this research, the fluid flow of gases in the stepped micro-channel at a wide range of knudsen number has been analyzed with using the lattice boltzmann (mrt) method. in the model, a modified second-order slip boundary condition and a bosanquet-type effective viscosity are used to consider the velocity...

For gas flows in microchannels, slip motion at the solid surface can occur even if the Mach number is negligibly small. Since the Knudsen number of the gas flow in a long microchannel can vary widely and the Navier-Stokes equations are not valid for Knudsen numbers beyond 0.1, an alternative method that can be applicable to continuum, slip and transition flow regimes is highly desirable. The la...

abstract: since the field of micro electromechanical systems (mems) continues to grow, the flow in micro devices have become an area that receives a significant attention. the microscopic flows are usually characterized by the knudsen number (kn). when the characteristic size of the particle decreases down to a value comparable to the mean free path of the molecules, the continuum assumption fa...

Classical continuummethods break down for rarefied gas flows inmicro-channels. Twononcontinuumhydrodynamicmodels are investigated here: compressible Korteweg fluid-like andBiVelocity (VolumeDiffusion) hydrodynamicmodels. The pressure driven rarefied gasflow in a rectangularmicro-channel in thewhole range of Knudsen number is numerically considered. The Kortewegmodel shows improved results in co...

For gas flows in microfluidic configurations, the Knudsen layer close to the wall can comprise a substantial part of the entire flowfield and has a major effect on quantities such as the mass flow rate through micro devices. The Knudsen layer itself is characterized by a highly nonlinear relationship between the viscous stress and the strain rate of the gas, so even if the Navier-Stokes equatio...