Influence of turbulence and atmospheric chemistry on grid size with respect to location in modeling and simulation of photochemical smog formation and transport

In models for photochemical smog formation and transport, mixing is assumed to be instantaneous and consequently the reactions are assumed to be kinetically controlled. In this work, the Damkohler number is calculated to check the validity of this assumption. The results show that this number is above 50, especially near pollution point sources such as the power station stacks, so that the diffusion limits the reactions for such cases. Using the irregular or adaptive grids minimized the Damkohler number and diffusion limitations which indicates that the grids should be finer near the source and coarser in remote regions. Therefore, depending upon the atmospheric conditions and emission sources, one can determine the optimum grid sizes for modeling and simulation of photochemical smog.