SCHOOL OF MECHANICAL ENGINEERING SEMINAR Monday, July 23, 2012 at 15:00 Wolfson Building of Mechanical Engineering, Room 206

Dept. of Civil and Environmental Engineering

Imperial College London

In this seminar I will discuss some recent progress on the theoretical description of turbulent mass transfer in conduits for high Schmidt number passive scalars. At high Schmidt number, the mass transfer boundary layer (MTBL) becomes extremely thin and becomes entirely nested in the viscous sublayer. Making use of the large difference between wall-normal and streamwise length scales, asymptotic solutions are developed both for the near- and the far-field. Closed-form solutions are presented for Dirichlet, Neumann, Robin boundary conditions, as well as a non-linear second-order wall-reaction. The influence of a first-order reaction in the fluid is discussed and it is shown that the increase in mass-transfer coefficient at high reaction coefficients is caused by MTBL thinning.

The final part of the seminar will discuss the influence of surface roughness. It will be shown that a rough geometry can reduce the mass-transfer and a simple conceptual model is presented which captures the salient features.

High Schmidt number turbulent mass transfer: asymptotic solutions and the influence of surface roughness

Dr. Maarten van Reeuwijk