RSS Feed SIMULATIONS OF COMPRESSIBLE CONVECTION AND TURBULENCE
Juri Toomre
Scientific Significance:
The purpose of this project is to conduct three-dimensional simulations of turbulent compressible convection under the influence of rotation. Our goals are to examine the redistribution of angular momentum that leads to the mean flows which we know as differential rotation within a star like our sun. These studies seek to resolve the challenge raised by helioseismology, which, via measurements of the acoustic modes of the sun, has probed the inner structure of the solar convection zone and revealed a differential rotation with depth and latitude that is not in accord with the predictions of earlier numerical models. Previous simulations dealt with effectively laminar flows, and we now believe that fully turbulent flows may yield very different transport properties for quantities including the angular momentum. We propose to use hybrid pseudo-spectral/finite-difference and piecewise parabolic method codes in local area models of turbulent convection constrained by f-plane and b-plane rotation to investigate the dynamical effects of an increasingly turbulent state. Further, we intend to investigate global models of rotating convection within a spherical shell. The results from such modelling may be tested and confronted with new observational data forthcoming from the GONG helioseismology experiment in the next few years. From the proposed theoretical simulations, primary clues and perhaps even a cogent picture may emerge of how the solar convection zone operates on the larger scales.
Numerical Approach and Performance:
As part of the GCAG on GAFD Turbulence, Paul Woodward and David Porter from the University of Minnesota, in collaboration with Juri Toomre of the University of Colorado, are performing simulations of compressible convection and turbulence on a variety of computing platforms. On the T3D they are using a piecewise parabolic method (PPM) to model the Euler equations of inviscid, compressible fluid flow. This method uses a piece wise-parabolic interpolation scheme which generates a parabola to describe the internal structure of a computational cell or zone of the grid. Porter has already started to do scientifically meaningful calculations on the T3D. The code uses PVM for message passing and also runs on a workstation cluster as well as on the C90.
The scaling is indistinguishable from linear.
10 MFLOPS/PE
32 PE = 0.6 Equivalent C90 CPU's
Back to Contents Page