|
|
 |
|
Seminar by Taku Ohwada |
|
Date: February 17, 2005
Time: 9:30am
Location: NIA, Rm 404
Speaker: Taku Ohwada, Kyoto University, Japan
Subject: "Kinetic Schemes for Finite Knudsen Number Flows: Deterministic Alternatives to DSMC"
Applications in space science and gaseous flows in nano- and micro-devices present problems that cover a wide range of Knudsen numbers (Kn). These applications require coupling Computational Fluid Dynamics (CFD) solutions in near-equilibrium regions (Kn~0) to solutions of the Boltzmann equation in nonequilibrium regions (Kn~O(1)). There has been considerable recent interest in particle-continuum hybrid methods which employ the Direct Simulation Monte Carlo (DSMC) technique as the Boltzmann solver. However, its stochastic nature makes DSMC subject to significant statistical noise; consequently, the required coupling to deterministic CFD becomes a difficult undertaking.
In this talk, we shall discuss our proposal for deterministic hybrid methods as alternatives to DSMC-CFD hybrids. The main idea of our proposal is to solve the Boltzmann equation at a level of sophistication and accuracy adapted to the problem, and to solve hydrodynamics with kinetic schemes based on the Boltzmann equation, thereby ensuring that the coupling between the two solutions is both theoretically consistent and numerically efficient. We will demonstrate the validity and the simplicity of the proposed deterministic hybrid approach by applying the conventional implicit finite difference method for the BGK equation with a gas-kinetic Navier-Stokes solver to some representative problems.
|
|
|
Home