Radiative transfer in decomposed domains

¹ NORDITA, Blegdamsvej 17, 2100 Copenhagen Ø, Denmark e-mail: theine@nordita.dk
² Niels Bohr Institute, Copenhagen University, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
³ Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
⁴ Kiepenheuer-Institut für Sonnenphysik, Schöneckstraße 6, 79104 Freiburg, Germany

Received: 23 March 2005
Accepted: 7 November 2005

Abstract

Aims. An efficient algorithm for calculating radiative transfer on massively parallel computers using domain decomposition is presented. Methods. The integral formulation of the transfer equation is used to divide the problem into a local but compute-intensive part for calculating the intensity and optical depth integrals, and a nonlocal part for communicating the intensity between adjacent processors. Results. The waiting time of idle processors during the nonlocal communication part does not have a severe impact on the scaling. The wall clock time thus scales nearly linearly with the inverse number of processors.