2014-04-30
10:15 at HCI J 574

Model reduction in kinetic theory by order of magnitude of moments.

Henning Struchtrup

Department of Mechanical Engineering, University of Victoria, Canada

Proper scaling of the kinetic equations describing rarefied gas flows introduces the Knudsen number, which can be used to reduce the description based on the order of magnitude of the Knudsen number. The order of magnitude method considers the reduction not of the kinetic equation itself, but of an associated system of moment equations. In its core, it combines elements of the Chapman-Enskog and Grad methods such that the benefits of both methods are retained, but their shortcomings are removed. The method yields a hierarchy of increasingly complex moment systems that are relevant for increasing order of the Knudsen number. The talk will highlight recent results for hard sphere molecules and polyatomic molecules, for which the scaling leads to two different Knudsen numbers and thus an increased level of complexity.