Abstract
A numerical simulation has been carried out to study the laminar flow in a symmetric sudden expanded channel subjected to a uniform blowing/suction speed placed at the lower and upper porous step walls. The governing equations for viscous flow have been solved using finite-difference techniques in pressure-velocity formulation. The results obtained here have been compared with the available experimental and numerical results of similar problems. It is noted that the recirculating region formed near the step walls diminishes in its length for increasing values of blowing speed applied at the porous step walls. For a suitable blowing speed, the recirculation zone disappears completely. The critical Reynolds number for the flow bifurcation (i.e. flow asymmetry) is obtained and it increases with the increase of the blowing speed. The critical Reynolds number for symmetry breaking of the flow decreases with the increasing values of suction speeds. The primary and the secondary recirculating regions formed near the channel walls are controlled using blowing.
Highlights
Laminar separated flows and the control of flow separation belong to one of the fundamental classes of flows which have attracted substantial attention in fluid mechanics over the years
Additional recirculation zones appear along the channel walls for further higher values of Reynolds number (Re)
We explore the effects of suction and blowing speeds placed at the porous step walls on flow separation and symmetry-breaking bifurcation in a twodimensional sudden expanded channel
Summary
Laminar separated flows and the control of flow separation belong to one of the fundamental classes of flows which have attracted substantial attention in fluid mechanics over the years. Two-dimensional laminar flow of an incompressible Newtonian fluid in a symmetric sudden expanded channel has been studied by several investigators. Experimental and numerical studies of Durst et al [1], Cherdron et al [2], Sobey and Drazin [3], Fearn et al [4], and Durst et al [5] investigated the sudden expansion channel flows with moderate expansion ratio. When the Reynolds number Re is relatively low, the flow is symmetric and the recirculating regions at the two channel walls are symmetric. With the increase of Reynolds number, the flow remains two-dimensional but asymmetry of the flow sets in. Additional recirculation zones appear along the channel walls for further higher values of Re. Recently, Chiang et al [6] reported the sidewall effects in
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