NIRVANA+: An adaptive mesh refinement code for gas dynamics and MHD Original Research Article

A 2D Cartesian fully adaptive mesh refinement code for problems of gas dynamics and magnetohydrodynamics is presented. The code has been developed as a first step towards a future 3D version to enable fluid dynamical modeling of real-world problems presently beyond a numerical treatment. The refinement concept is based on the well-known strategy of multiple nested, successively refined, structured grid patches overlaid a fixed main grid. Adaptive grid technology is implemented in a numerical scheme which makes use of standard finite difference/finite volume formulations featuring global conservation of mass and the divergence-free magnetic field evolution with high accuracy. The performance of the new code NIRVANA+ is checked by hard test computations: the double Mach reflection problem of a strong shock, the circular advection of a current-carrying cylinder, and the dynamical evolution of a magnetohydrodynamic vortex.