LELUYA - the Next Generation Radiative Transfer Modeling


Whenever energy in the form of radiation travels through a medium, it is absorbed, scattered, and reemitted. We study the medium by observing such reprocessed energy. The medium can be a dust cloud around a star or in a galaxy, the Earth's atmosphere, a human body, etc. Not surprisingly, numerical models of radiative transfer appeared together with the first computers. Since then, the algorithms have evolved and been able to calculate exact solutions to one-dimensional geometrical configurations (sphere or slab). However, there is still no a robust exact solver for multidimensional configurations. Current state of the art computer codes can handle it only by Monte Carlo techniques on simplified numerical grids, often with limited precision, or by applying approximate methods and trivial configurations to simplify the problem.

Astronomical observations of objects deeply imbedded in dust cannot be studied without an exact solution of the multidimensional radiative transfer problem. LELUYA is the first code capable of solving exactly an arbitrary axially symmetric multi-grain dust distribution around a heating source. A newly developed parallel algorithm automatically traces the dust density and optical depth gradients, creating the optimal adaptive grid, which is highly unstructured and triangular. Different grids are created this way for different wavelengths to accommodate the spectral variation of dust opacity. The radiative transfer problem, including dust absorption, emission and scattering, is solved exactly.