Example 1: Backward facing step (fluid flow)

The following specific case of the GAMM workshop [6] is studied here:

total length of channel $L=22$.

length inflow section $l=3$.

total height $H=1$.

height inflow section $h=0.5$.

viscosity $\nu=0.01$.

density $\rho=1$.

maximum flow component of parabolic profile in inflow section $U_{max}=1$.

the flow volume is $(2/3)hU_{max}=1/3$.

Reynolds $Re= U_{max}(H-h)/\nu = 50$.

The result for the minimum x-velocity $v_x$ at distance $x=0.8$ behind the step is studied. This result checks the correct modeling of the recirculation zone after the step. At the distance $x=0.8$ we find the minimum velocity is $v_x = -0.041$. This happens at $y=0.1$ above the lower edge. The results of the GAMM workshop were in between $-0.066$ and $-0.018$.