3D CONVECTION AT INFINITE PRANDTL NUMBER IN CARTESIAN GEOMETRY - A BENCHMARK COMPARISON

We describe the results of a benchmark study of numerical codes design ed to treat problems of high Prandtl number convection in three-dimens ional Cartesian geometry. In addition, quantitative results from labor atory convection experiments are compared with numerical data. The cas es of bimodal convection at constant viscosity and of square cell conv ection for temperature-dependent viscosity have been selected. We comp are the Nusselt number, local velocity, temperature, heat flow, topogr aphic and geoid anomalies for stationary solutions. A case of transien t time-dependent behavior and the stability limit of bimodal flow are also subject to a comparison. We obtain reasonable agreement among the eight tested codes; and some solutions, which agree within narrow lim its, are taken to define a reference for further testing of codes. The results from laboratory experiments agree with the numerical data wit hin the expected range of uncertainty.