2ND-ORDER-ACCURATE RADIATIVE HYDRODYNAMICS AND MULTIDIMENSIONAL PROTOSTELLAR COLLAPSE

A second-order-accurate numerical scheme for computing the radiative hydrodynamics of three-dimensional, collapsing protostellar clouds has been developed and implemented in both spherical and cartesian coordinates. The scheme employs spatially second-order-accurate advective fluxes based on van Leer monotonic interpolation and consistent advection. The advective fluxes also contain the terms necessary to make the scheme temporally second-order-accurate in the presence of spatially and temporally varying velocity fields. A predictor-corrector treatment of the source terms completes the requirements for second-order accuracy in time. The Poisson equation for the gravitational potential is solved by either a spherical harmonic expansion or a Green's function method. Radiative transfer in the Eddington approximation is handled through the solution of a mean intensity equation. The numerical scheme has been shown to be second-order-accurate through convergence testing and has been shown to improve the performance on a shock propagation problem compared to schemes that do not contain the spatially and temporally second-order-accurate terms.