Most of the interesting physics occurs in predictable regions of the simulation volume, so the simulations also vary the grid scale accordingly and take advantage of some processing shortcuts, according to Ricker. By placing small simulation zones where high resolution is needed and larger cells outside the main interaction region, he uses fewer processors and substantially cuts the simulation's processing time. His first runs on the Texas T3E ran for about 48 hours each on 32 processors. We'd like to do high-resolution runs at two values of each parameter to better resolve the cooling flows and to check the convergence of the results. Next Figure 2.
Gas density is shown by log contours and temperature by color.
Arrows indicate direction of gas flow. In an example merger, a strong shock front dissipates the cluster cores' kinetic energy as heat in the surrounding gas. The infalling cores drive curved bow shocks that transfer the cores' angular momentum to the surrounding gas. Long after the collisional shock front has passed through the cluster volume, material in its wake falls back toward the merged cores and creates a secondary accretion shock around the cluster. The evolution of the cooling flows seems to depend on the mass ratio and impact parameter, but in unexpected ways.