The buoyancy effects are maximal in upflow regions that are broader scale than the sites of strong shear, the narrow downflow regions. Thus the two contributions to the coefficients of viscosity and thermal diffusivity arise from different spatial locations and are of different scales. The contribution of buoyancy effects in the model produces detectable differences in energy spectra and the time dependence of some global quantities. The time step limitation imposed by having to resolve both sound and Alfven waves for a deep atmosphere is also very severe, thus an implicit method of time integration can be preferable in some circumstances. The staggered mesh system can prevent the development of numerical instabilities in the direction of gravity and avoids redundant computational effort.
Further improvements are underway.
This code has been instrumented, and parallel performance data have been collected on the IBM SP2 at Maui. A Networked Virtual Reality Application R. Hudson and A. Malagoli have developed a prototype virtual environment that makes use of the CAVE to perform interactive volume visualization of 3-D turbulence data from simulations.