Direct Numerical Simulation of Turbulent Mass Transfer Around a Rotating Stepped Cylinder

Direct Numerical Simulation was carried out to predict mass transfer in turbulent flow around a rotating stepped cylinder. An immersed boundary method was employed for efficient implementation of the irregular cylinder surface on the cylindrical grid system. This investigation is a follow-up study of Nesic et al. [Corrosion, Vol. 56, No. 10, pp. 1005 – 1014] The original motivation of this work stemmed from the efforts to design a simple device which can generate flows of high turbulence intensity at low cost for corrosion researchers. Two cases were considered; Sc = 1 and 10 both at Re = 335. Here, Sc and Re stand for Schmidt number and Reynolds number, respectively, based on the step height and the surface speed of the cylinder upstream of the step. Characteristics of the averaged concentration field are presented and analyzed. Correlation between the wall-shear stress and the mass-transfer rate is also discussed. The numerical results are qualitatively compared with those of experiments conducted with a similar flow configuration.