Isotropic-turbulence-induced mass transfer across a severely contaminated water surface

Direct numerical simulations were performed to investigate the effect of severe contamination on interfacial gas transfer in the presence of isotropic turbulence diffusing from below. A no-slip boundary condition was employed at the interface to model the severe contamination effect. The influence of both Schmidt number (Sc) and turbulent Reynolds number (R-T) on the transfer velocity (K-L) was studied. In the range from Sc = 2 up to Sc = 500 it was found that K-L proportional to Sc-2/3, which is in agreement with predictions based on solid liquid transport models, see e.g. Davies (1972, Turbulence Phenomena, Academic). For similar R-T, the transfer velocity was observed to reduce significantly compared with the free slip conditions. The reduction becomes more pronounced with increasing Schmidt number Similar to the observation for free-slip conditions made by Theofanous et al. (Intl J. Heat Mass Transfer, vol. 19 (6), 1976, pp. 613-624), the normalized K-L in the present no-slip case was also found to depend on R-T(-1/2) and R-T(-1/4) for small and large turbulent Reynolds numbers. respectively