Flows through plane sudden-expansions

Occurrence of asymmetric flow pattern behind a double

“…Each figure shows the mean velocity field attached on upper wall (Fig.3(a)) and that on the lower wall ( Fig.3(b)). These results show the presence of two flow patterns in the flow behind a double orifice in a square pipe, which is in contrast to the observation of singularity in the sudden expansion in a rectangular pipe (Aloui and Souhar, 2000;Zilwa et al, 2000). Although these two flow patterns are found to be repeatable, the selection mechanism is not clear in the present state.…”

Asymmetric flows of viscoelastic fluids in symmetric planar expansion geometries

“…Such level of agreement is remarkable as it would appear that the exact "location" of the bifurcation, in terms of Reynolds number, would be rather sensitive to a number of variables, as mesh resolution, numerical precision, initial conditions, triggering mechanism, etc. In most earlier calculations of these phenomena, the asymmetric flow was usually triggered by introducing a slight geometrical asymmetry in the symmetric configuration, or by adding a small perturbation to the velocity profile imposed at inlet, or to the whole initial velocity field [10,11,13,29,30]. In fact, we found that such artificial triggering devices are not required and in our case the numerical solution naturally evolved to an asymmetric flow when the Reynolds number was above the critical value, Re c .…”

“…As a further check for the same expansion ratio E = 3, we compare our predictions against those of Da Zilwa et al [30] for the case Re = 187 (Re 0 = 280), when a second bifurcation occurs and a new recirculation zone appears by the wall adjacent to the smaller comer vortex. The situation is then as depicted in Fig.…”

“…All these pressures were obtained from the simulation results, f Re could then be calculated from Eq. (30) and is plotted as a function of the Reynolds number in Fig. 18.…”

Parallel pseudo-transient Newton–Krylov–Schwarz continuation algorithms for bifurcation analysis of incompressible sudden expansion flows

“…[14] 40.45(S), 44(E) Shapira et al (1990) [41] 107.5(L) 41.3(L) Durst et al (1993) [13] 62.5(S) Drikakis (1997) [12] 108(S) 40(S) 20.5(S) Foumeny et al (1996) [15] 40(S) Alleborn et al (1997) [1] 109(S)(L) 40(S) Battaglia et al (1997) [3] 112 [11] 92.5(S) 44(S) Mizushima and Shiotani (2000) [34] 40.23(S) Schreck and Schäfer (2000) [40] 40.7(S) Hawa and Rusak (2001) [22] 40.35(S)(L) Kadja and Bergeles (2002) [27] 100(S) Mishra and Jayaraman (2002) [33] 40.5(S) Wahba (2007) [45] 108 …”