A second-order positivity-preserving well-balanced finite volume scheme for Euler equations with gravity for arbitrary hydrostatic equilibria

We present a well-balanced finite volume solver for the compressible Euler equations with gravity where the approximate Riemann solver is derived using a relaxation approach. Besides the well-balanced property, the scheme is robust with respect to the physical admissible states. Another feature of the method is that it can maintain general stationary solutions of the hydrostatic equilibrium up to machine precision. For the first order scheme we present a well-balanced and positivity preserving second order extension using a modified minmod slope limiter. To maintain the well-balanced property, we reconstruct in equilibrium variables. Numerical examples are performed to demonstrate the accuracy, well-balanced and positivity preserving property of the presented scheme for up to 3 space dimensions.