Numerical studies of a three-dimensional flow in suddenly contracted channels

This paper aims to provide deeper insight into the suddenly contracted channel flow. The channels under investigation have a width of 18D, where D represents the channel height upstream of the step plane, and two contraction ratios: C=2 and 4. In the present three-dimensional finite volume analysis, the advective fluxes are discretized using an upwind scheme that provides a third-order accurate solution in uniform grid cases. For efficient calculation of field variables, working equations are solved separately based on the semi-implicit velocity-pressure coupling procedures. We exploit a theoretically appealing topological theory to determine lines of separation and reattachment, from which the pitchfork bifurcation flow can be identified in the contraction channel. To further elucidate the vortical details of the channel flow, we trace massless particles seeded in the flow, showing the spanwise spiraling flow motion. Emphasis is placed on flow phenomena in the upstream salient corner eddy and downstream tip corner eddy. (C) 2002 American Institute of Physics.