Essential components of the KOSMA-tau PDR modelling approach

PDR model for fractal source

The model has to simulate processes from the nm scale to the pc scale. On the large scale we find a filamentary, fractal structure illuminated by UV radiation. We describe this structure in terms of turbulence models and simulate it as a superposition of clumps. Using a size distribution of clumps, we can mimick any fractal distribution. Within the individual clumps, we solve the radiation transfer problem, the energy balance, and the chemical structure to predict the full physical and chemical structure and line intensities that can be compared with observations in the infrared and millimeter range.