Comparison Runs

I spent today playing with visualizing these runs in visit, and adjusting some of the parameters in the data files. Here is a plot summarizing some of my findings -

Focusing on the left column of the plot, we see the field restricts the lateral dispersal of the collision region away from the colliding streams. This seems to have 3 important effects. 1) In the hydro run, the clumps fragment and become localized structures moving in the flow, whereas in the MHD run a long filamentary structure forms. 2) The 'clumping' of material in the MHD run is enhanced, producing higher densities than in the Hydro run. A sink particle forms in the MHD run by frame 134, but does not form (at least by the final frame 140) in the hydro run. 3) The collision region seems bound in the MHD run, but not in the hydro run.

The right column shows the following: without cooling, we see the collision region expands (quickly) — increasing density leads to increased pressure, which forces the evacuation of the gas. In the hydro case, we see little localized clumps of lower density material form within the collision region. These structures do not form in the MHD runs, but rather we see again longer filamentary structures form there.

The boundary conditions are reflecting on left and right, and extrapolating on top and bottom. The behavior in the hydro, non-cooling case makes sense with these BCs, but I am not entirely sure what is going on in the MHD non-cooling case where there is some weird flow coming back into the grid on the top and bottom..

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1. Jonathan -- 11 years ago

Just a reminder that in 2D there is an inverse cascade of eddies to larger scales - so I don't expect those large eddies to show up in 3D.