Resumen
Measured O/H ratios in the ISM suggest an homogeneous distribution while D/H suggests that deuterium is far from homogeneous. To study this, we added a tracer field to the ISM model of de Avillez (2000) to study mixing and dispersal in kiloparsec-scale simulations of the ISM with different supernova rates and different inhomogeneity length scales. We find that classical mixing length theory fails to predict the very weak dependence of mixing time on length scale that we find on scales of 25 to 500 pc. Derived diffusion coefficients increase exponentially with time, rather than remaining constant. The variance of composition declines exponentially, with a time constant depending on the inverse square root of the supernova rate. One major reason for these results is that even with numerical diffusion exceeding physical values, gas does not mix quickly between hot and cold regions.
