Title of article :
A New Relaxation Time Model for Lattice Boltzmann Simulation of Nano Couette Flows in Wide Range of Flow Regimes
Author/Authors :
Ghatreh Samani, S Department of Mechanical Engineering - Najafabad branch, Islamic Azad University, Najafabad, Iran , Meghdadi Isfahani, A. H Department of Mechanical Engineering - Najafabad branch, Islamic Azad University, Najafabad, Iran
Abstract :
The standard LBM with the relaxation time is only able to simulate the flow features in continuum and slip
regimes. In the present paper, a new relaxation time formulation considering the rarefaction effect on the
viscosity for the lattice Boltzmann simulation of shear driven flows is presented in order to cover wide range
of the flow regimes. The results show that in spite of the standard Lattice Boltzmann Method, LBM, the
presented relaxation time equation is able to predict flow features in wide range of flow regimes including
slip, transition and to some extend free molecular flow regimes. The velocity profiles, slip length and shear
stress agree very well with DSMC (Direct Simulation Monte Carlo) and linear Boltzmann results.
Keywords :
Rarefaction , Relaxation time , Knudsen number , Transitional regime , Micro and nano- Couette , Lattice Boltzmann method
Journal title :
Astroparticle Physics
