On a DG Method for Two-Moment Radiation Transport with Applications in Nuclear Astrophysics

Abstract: When modeling radiation transport through a fast-moving fluid, such as in relativistic astrophysical systems, adopting momentum space coordinates associated with a frame of reference comoving with the fluid simplifies the inclusion of radiation-matter interactions.  However, this choice of momentum space coordinates complicates the discretization of the phase-space advection operator by the appearance of velocity-dependent terms.  In this context, we consider a conservative, multidimensional, spectral two-moment model in special relativity, and propose a numerical method for evolving this model.  The method is based on discontinuous Galerkin phase-space discretization and implicit-explicit time stepping, and is designed to maintain physically realizable moments during evolution.  Part of the seminar will be devoted to key aspects of the physical model and its main motivating applications: exploding massive stars and colliding neutron stars.  Numerical results that demonstrate the capabilities of the proposed method will also be presented.

Speaker’s Bio:  Eirik Endeve is a staff researcher in the Oak Ridge National Laboratory’s Multiscale Methods and Dynamics Group.  He received his Ph.D. from the Institute of Theoretical Astrophysics at the University of Oslo.  His current research interests include methods for solving kinetic equations, structure-preserving discretization of hyperbolic partial differential equations, and the development of methods for multiscale problems in physics applications.