Heat transfer in the transition regime: solution of boundary value problems for Grad's moment equations via kinetic schemes.

Abstract

This paper presents a systematic approach to the calculation of heat transfer in rarefied gases (Knudsen numbers between 0.01 and 1) by means of Grad's moment method with high moment numbers, based on the Boltzmann equation with linearized collision term. The problem of describing boundary conditions for the moments is solved by the use of the so-called kinetic schemes that allow the implementation of the boundary condition for the Boltzmann equation. The results, obtained with up to 48 one-dimensional moment equations, exhibit temperature jumps at the walls with adjacent Knudsen boundary layers. For given wall temperatures and Knudsen number, the results change with the number of moments, and converge if the number of moments is increased.