GEM Reconnection Problem Code Comparisons

The GEM reconnection problem is described in [J. Birn, J. F. Drake, M. A. Shay, et al., J. Geophys. Res. 106 3715 (2001)]. The CEMM is using this well-defined 2D test problem as one of it's benchmark problems. We present results from several codes for both the "resistive MHD" model, and for the "two-fluid" model, which has the Hall terms added to the generalized Ohm's law.

**Phase I: Resistive MHD****Phase II: 2-Fluid (Hall) MHD****Code Descriptions and Parameters**

The form of the resistive MHD equations used, and the parameters for this problem are given here . We present comparisons for two values of the fluid viscosity. In the first, the dimensionless viscosity is 10 times the dimensionless resistivity. This is the "high viscosity case" and is the one described in the writeup. In the second, the viscosity is reduced by a factor of 100, so that it is 1/10 times the dimensionless resistivity. This is the "low viscosity case". References for the codes and for the resolution settings are given near the bottom of this page.

The form of the 2-fluid MHD equations used, and the parameters for this problem are given here .

A descriptions of the codes applied to this problem and the parameters they used in the solution are given here.

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More details regarding the M3D-C1 code applied to this problem, including some extensions to the case of a non-zero guide field, are given in the July 2006 SIAM presentation .

The exact equations being solved by the SEL code are given here . Some variations for SEL around the baseline are given here . The midplane profiles for the case nu = 5.E-6 and Dn=0 are shown here . Results for a full-domain simulation with the SEL code (9/12/06) are given here .

please email contributions to jardin@pppl.gov