Simulating magnetised plasma with the versatile advection code

Matter in the universe mainly consists of plasma. The dynamics of plasmas is controlled by magnetic fields. To simulate the evolution of magnetised plasma, we solve the equations of magnetohydrodynamics using the Versatile Advection Code (VAC). To demonstrate the versatility of VAC, we present calculations of the Rayleigh-Taylor instability, causing a heavy compressible gas to mix into a lighter one underneath, in an external gravitational field. Using a single source code, we can study and compare the development of tills instability in two and three spatial dimensions, without and with magnetic fields. The results are visualised and analysed using IDL (Interactive Data Language) and AVS (Advanced Visual Systems). The example calculations are performed on a Cray J90. VAC also runs on distributed memory architectures, after automatic translation to High Performance Fortran. We present performance and scaling results on a variety of architectures, including Cray T3D, Cray T3E, and IBM SP platforms.