backward_step, a FreeFem++ code which solves the backward step benchmark problem for Navier Stokes flow.
The backward step geometry is:
| y=H +--------------L5--------+ y=H
| | |
| L1 L2
| | |
| y=0.5 +-L4--+ |
| L4 |
| y=0 +--------L3--------+ y=0
| ^ ^ ^
| x=0 x=3 x=22
|
+--------------------------------------------------
In flow case 1, H = 1.5, and in flow case 2, H = 1.
Solutions are desired at Reynolds numbers 50, 150, 500.
Side L1 is an inflow boundary, with a parabolic inflow profile:
uinflow = (H-y)*(y-1/2)/((H-1/2)/2)^2
Side L2 is an outflow boundary where boundary conditions are not imposed.
Sides labeled L3, L4 and L5 are no slip walls, with U = V = 0.
The steady incompressible Navier Stokes equations for (u,v,p) in 2D are:
-nu ( uxx + uyy ) + u ux + v uy + px = 0
-nu ( vxx + vyy ) + u vx + v vy + py = 0
ux + vy = 0
where nu is the kinematic viscosity.
The computer code and data files described and made available on this web page are distributed under the MIT license
