A symmetry-breaking inertial bifurcation in a cross-slot flow

In the current paper we investigate, using a numerical technique, a new bifurcation phenomenon for a Newtonian fluid flowing through a two-dimensional so-called "cross-slot" geometry. A cross-slot, or cross-channel, geometry is formed by an "horizontal" planar channel along which two incoming fluid streams are made to impinge on each other, and an intersecting "vertical" channel which carries the outlet flow, with the other two streams now moving away from the central section and leaving through the vertical channel exits. At low Reynolds numbers (Re) the flow remains steady and symmetric and identical regions of standing recirculation attached to the four corners increase linearly in size with Re. At a critical Reynolds number (=1490 +/- 10) a supercritical pitchfork bifurcation is observed beyond which the unstable symmetrical solution is replaced by a pair of steady asymmetric solutions (each corresponding to larger recirculation regions on one vertical sidewall). The dynamics of the bifurcation are investigated in detail and a comparison made with the bifurcation observed for inertialess viscoelastic fluid flow. (C) 2014 Elsevier Ltd. All rights reserved.