Numerical solution of multi-component species transport in gases at any total number of components

In Böttcher [K. Böttcher, Numerical solution of a multi-component species transport problem combining diffusion and fluid flow as engineering benchmark, Int. J. Heat Mass Transfer 53 (1–3) (2010) pp. 231–240], one of us described an implementation of ternary multi-component species transport by diffusion and convection and presented benchmark cases and simulation results for these cases computed with software ENTWIFE. In this paper, an implementation of the Stefan–Maxwell equation into the ANSYS CFX software is described in combination with a procedure to numerically calculate the ordinary multi-component diffusion coefficients in gases at any total number of components. Finally, the benchmark for ternary mixtures is extended to a quarternary one. A comparsion to the benchmark results of Böttcher revealed an implementation mistake in Böttcher’s paper leading to wrong results in case of largely different molar masses. The correct benchmark results are presented here and furthermore compared to two different kinds of effective binary diffusion approaches in multi-component gas mixtures.