2001-11-21
10:15 at ML H43

Boundary layer minimum entropy production principle: A case study

Iliya Karlin

Institute of Polymers, ETH Zurich

One of the well known problems of computational fluid mechanics is how to pose boundary conditions for systems with many field variables. In this talk, I will present a recent study of why, how, and to what extend modifications of the Glansdorff-Prigogine variational principle of minimum of the entropy production can be adopted to resolve this problem. Models studied are toy heat conduction problems for moment equations derived from the Boltzmann kinetic equation by Grad's method. It is demonstrated that the structure of minima of the entropy production sampled over boundary layers exibit a crossover at a certain thickness of the layer. Minimum principles are suggested on the basis of this observation, and compared to the recently proposed minimax principle [Struchtrup and Weiss, Phys. Rev. Lett., 80. 5048 (1998)].