On entry-flow effects in bifurcating, blocked or constricted tubes

• DOI: 10.1017/s002211207600270x
• Publication Date: 2006-04-11T17:07:00Z
• Authors: F. T. Smith
• Keywords: Inviscid flow; Pipe flow; Secondary flow; Length scale; External flow

For practically uniform entry conditions, the features of steady laminar flow produced by a particular small distortion walls channel or pipe are shown to alter first from those corresponding external situation when is in an ‘adjustment zone’, sited large distance O(R⅗l) inlet; R ([Gt ] 1) and l signify respectively typical Reynolds number length scale incompressible fluid motion. The planar there develops extended triple-deck structure, with unknown inviscid core motion bounded two-tiered boundary layers near walls. In three-dimensional flow, where similar structure occurs, induced secondary has jet-like nature close wall. size position indentation govern properties within this adjustment regime both can lead large-scale effects being propagated. most substantial occur if indentation, interior blockage bifurcation just downstream stage channel. pipe, however, such siting induces much less upstream influence, instead significant long-scale disturbances generated constricted asymmetrically over length. Vortex then be provoked far beyond constriction, sense rotation changing as moves further downstream, while source-like found.