Geophysical and Astrophysical Fluid Dynamics Vol. 98, No. 3, June 2004, pp. 241–255 2D STUDIES OF VARIOUS APPROXIMATIONS USED FOR MODELING CONVECTION IN GIANT PLANETS MARTHA EVONUK* and GARY A. GLATZMAIER Department of Earth Sciences, University of California, Santa Cruz, CA, 95064 USA (Received 23 August 2003; In final form 13 January 2004) The effects of common approximations made when modeling convection in the interior of giant planets, like Jupiter, are examined using two-dimensional (2D) numerical calculations at high Rayleigh number (10 10 ). Small scale flow structures along the upper boundary and large scales in the lower region are observed for an anelastic fluid spanning five density scale heights. A much more symmetric distribution in the scale of flow structures is observed for a Boussinesq fluid in which density stratification is neglected. The absence of magnetic fields results in higher fluid velocities and smaller scale flow structures. Neglecting the inertial terms produces narrower plumes and a fundamentally different fluid flow pattern for anelastic fluids. Although restricted to two dimensions, our results demonstrate that the spatial structure and time dependence of thermal convection are significantly influenced by density stratification, magnetic fields and inertia. These effects should not be ignored in three-dimensional (3D) convection models of giant planets. Keywords: Giant plants; Numerical modeling 1 INTRODUCTION Approximations, such as assuming constant density and neglecting magnetic fields and inertial terms, are often used when modeling convection in the interior of giant planets like Jupiter. Models with these approximations, however, may not accurately capture the fluid dynamics within these giant planets. For example, giant gaseous planets experience a significant change in density with depth (Guillot, 1999). Models that assume a constant background density profile, the Boussinesq approximation, are approximately valid only for very thin shells within a giant planet. However, deep inter- ior models of Jupiter have employed the Boussinesq approximation (e.g., Sun et al., 1993; Aurnou and Olson, 2001; Christensen, 2001, 2002; Wicht et al., 2002). Shock pressure experiments suggest that hydrogen in Jupiter should become metallic at roughly 1.4 Mbars (Nellis et al., 1996) which corresponds to about 0.84 of Jupiter’s radius (Guillot, 1999). Convection of this electrically-conducting hydrogen in the deep *Corresponding author. E-mail: mevonuk@emerald.ucsc.edu ISSN 0309-1929 print: ISSN 1029-0419 online ß 2004 Taylor & Francis Ltd DOI: 10.1080/03091920410001696126