# University of Minnesota

Aerospace Engineering and Mechanics

**Winter 1999 Seminar Series**

*Boltzman Equation, Chapman-Enskog Expansion, and Rivlin-Ericksen
fluids*

*Abstract*

### The classical Chapman-Enskog expansion provides a bridge between the
kinetic description of gas dynamics and continuum mechanics. However truncation
of this expansion beyond (first) Navier Stokes order yields instability of the
rest state. A special case of Chapman-Enskog is obtained when the constraint of
constant density is imposed: the Rivlin-Ericksen fluid which of course exhibits
the same instability phenomena upon truncation. This talk illustrates how an
approximate sum of the Chapman-Enskog expansion eliminates the instability
paradox via derivation of a generalized Clausius-Duhem inequality.

### Friday, February 5, 1999

209 Akerman
Hall

2:30-3:30 p.m.

### Refreshments served after the seminar in
227 Akerman Hall.

Disability accomodations provided upon request.

Contact Kristal Belisle, Senior
Secretary, 625-8000.