EFFECTIVE-MASS DIFFUSION OVER CELL BOUNDARIES IN A TAYLOR-COUETTE FLOW SYSTEM

Effective mass diffusion over cell boundaries in a Taylor-Couette how system was investigated ranging from singly periodic wavy vortex flow to weakly turbulent wavy vortex flow by a salt-solution tracer techniq ue. In order to determine experimentally the intercell mixing coeffici ent k(CB) between the neighbouring pairs of vortices, an appropriate m odel was formulated. As a result, k(CB) depends not only on Taylor num ber but also on axial wavelength with fluid viscosity. In the singly p eriodic wavy vortex flow region, the intermixing is enhanced by period ic fluctuations resulting from azimuthally travelling waves on the cel l boundaries. With increasing Taylor number in the doubly periodic wav y vortex flow and weakly turbulent wavy vortex flow regions, the mixin g characteristics go toward axial turbulent diffusion. In these two fl ow regions, the correlation between k(CB) and effective diffusion coef ficient D-z based on an axial diffusion model has been obtained as D-z = 2 lambda k(CB). (C) 1997 Elsevier Science Ltd.