Numerical simulations of mass transfer in turbulent pipe flow at high schmidt numbers

Numerical simulations for the wall mass transfer in a turbulent pipe flow were performed at Reynolds numbers (Re) of 40,000, 70,000 and 100,000 and Schmidt number (Sc) of 100, 200, 400 and 1280. Six versions of Low Reynolds Number (LRN) k-ε turbulence models were evaluated by examining the variation of the turbulent viscosity and diffusivity in the wall-normal direction. The predicted values of the turbulent viscosity and diffusivity from the AKN Low Reynolds Number model closely follow the cubic dependence in the near-wall region and found suitable for mass transfer simulations at high Schmidt numbers. The near-wall region was resolved down to y+=0.14 for Reynolds number of 100,000, which allowed the mass transfer to be obtained from the near-wall concentration profile. The exponent of the Schmidt number dependence on the Sherwood number was approximately 0.333 and in agreement with existing mass transfer correlations and experimental data for smooth pipe flow. The predicted mass transfer coefficient was in good agreement with pipe flow results and with experimental and numerical mass transfer results that yielded different Schmidt number dependences over the range considered.