Improved discretization of the wavelength derivative term in CMF operator splitting numerical radiative transfer

¹ Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany e-mail: yeti@hs.uni-hamburg.de
² Dept. of Physics and Astronomy & Center for Simulational Physics, University of Georgia, Athens, GA 30602-2451, USA
³ Dept. of Physics and Astronomy, University of Oklahoma, 440 W. Brooks, Rm 131, Norman, OK 73019-0225, USA
⁴ NERSC, Lawrence Berkeley National Laboratory, MS 50F-1650, 1 Cyclotron Rd, Berkeley, CA 94720-8139, USA
⁵ Laboratoire de Physique Nucléaire et de Haute Énergies, CNRS-IN2P3, University of Paris VII, 75005 Paris, France

Corresponding author: E. Baron, baron@nhn.ou.edu

Received: 8 October 2003
Accepted: 17 December 2003

Abstract

We describe two separate wavelength discretization schemes that can be used in the numerical solution of the comoving frame radiative transfer equation. We present an improved second order discretization scheme and show that it leads to significantly less numerical diffusion than the previous scheme. We also show that due to the nature of the second order term in some extreme cases it can become numerically unstable. We stabilize the scheme by introducing a mixed discretization scheme and present the results from several test calculations.