A compressible magnetohydrodynamic numerical code with time-dependent boundary conditions in cylindrical geometry

We describe a numerical code to study the magnetohydrodynamic (MHD) turbulence in a reversed field pinch (RFP) configuration by solving the compressible MHD equations in cylindrical coordinates. The compressibility requires that particular attention should be paid to the boundary conditions to have an accurate control of wave reflections from the boundaries of the computational domain. To fulfill these requirements the boundary conditions are calculated by a decomposition into characteristic waves. We present a method to calculate such boundary conditions in curvilinear coordinates and we apply it to the solution of the MHD equations in cylindrical geometry.