An Adaptive Projection Method for
               Modeling Low Mach Number Flows

                             by

                        Ann Almgren*
           Lawrence Berkeley National Laboratory

         JTB 120,  3:20pm Monday, February 24, 1997

                          Abstract

 Interesting problems in computational modeling are often
 characterized by the need for much higher resolution in
 certain regions of the domain than in others.  To achieve
 the desired accuracy on a uniform grid would be beyond the
 scope of current computational resources.  Adaptive mesh
 refinement, which increases the resolution in the regions
 of most interest, allows one to model large problems more
 efficiently.

 In this talk I present a projection method for solving
 time-dependent low Mach number equations, such as those
 given by the anelastic model of the atmosphere or those
 governing low speed combustion, on an adaptive hierarchy of
 grids. The incompressible Navier-Stokes equations are used
 as a prototype for demonstrating how to handle the
 hyperbolic vs. elliptic nature of the evolution and
 constraint equations governing these flows.

 The approach to adaptive refinement presented here uses a
 nested hierarchy of structured grids with simultaneous
 refinement of the grids in both space and time.  Multiple
 grids per level as well as multiple levels of refinement
 are allowed, and the grids are dynamically created and
 destroyed as the resolution requirements change.

 Results will be presented from several three-dimensional
 calculations.


*Dr. Almgren's visit is sponsored by the Center for High
 Performance Computing.

Requests for preprints and reprints to: ASAlmgren@lbl.gov
This source can be found at http://www.math.utah.edu/research/
or visit the Center for Computational Sciences and
Engineering web site at http://www.nersc.gov/research/CCSE/