A grey diffusion acceleration method for time-dependent radiative transfer calculations

Conference · Mon Jul 01 04:00:00 EDT 1991

OSTI ID:5300883

Nowak, P F

The equations of thermal radiative transfer describe the emission, absorption and transport of photons in a material. As photons travel through the material they are absorbed and re-emitted in a Planckian distribution characterized by the material temperature. As a result of these processes, the material can change resulting in a change in the Planckian emission spectrum. When the coupling between the material and radiation is strong, as occurs when the material opacity or the time step is large, standard iterative techniques converge very slowly. As a result, nested iterative algorithms have been applied to the problem. One algorithm, is to use multifrequency DSA to accelerate the convergence of the multifrequency transport iteration and a grey transport acceleration (GTA) followed by a single group DSA. Here we summarize a new method which uses a grey diffusion equation (GDA) to directly solve the multifrequency transport (S{sub N}) problem. Results of Fourier analysis for both the continuous and discretized equations are discussed and the computational efficiency of GDA is compared with the DSA and GTA nested algorithms. 5 refs., 1 fig., 1 tab.

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5300883
• Report Number(s): UCRL-JC-108009; CONF-911107--29; ON: DE91017653
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400 -- Engineering-- Heat Transfer & Fluid Flow
657002* -- Theoretical & Mathematical Physics-- Classical & Quantum Mechanics
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALGORITHMS
CONVERGENCE
DIFFUSION
ENERGY TRANSFER
HEAT TRANSFER
ITERATIVE METHODS
MATHEMATICAL LOGIC
TIME DEPENDENCE