Gasdynamic and magnetohydrodynamic modeling of the magnetosheath: A tutorial

Abstract

A review is presented of the current status of the MHD and gasdynamic convected magnetic field (GDCF) modeling of solar wind plasma flow in a planetary magnetosheath. The MHD model is fundamentally more accurate, but computational difficulties only now being surmounted have limited available solutions to a few cases. The GDCF model, derived as a tractable approximation to the MHD model, has reached a mature state in which a solution can be obtained in a few seconds using a work station. The accuracy and usefulness of the results are demonstrated by comparisons with corresponding MHD solutions and with observations for the earth and other planets for which insitu observations are available. Some of these are described here for the first time. All magnetosheaths display a basic similarity, but the size and certain other features vary greatly because of differences in conditions, particularly the distance from the sun, relative importance of the planetary magnetic field and ionosphere, importance of ion pickup processes etc. These are faithfully described by the GDCF model and, by inference, the MHD model. The paper closes with a brief discussion of related applications to the moon and the heliosphere, and general remarks.