Does anyone know a good source (possibly online)of test data for 2d laminar flows (like the backward facing step)? Thank you

Hey, there. Fisrt, you may want ot start with the simpler flows like Poiseuille flow, i.e. fully developed laminar flow between two parallel plates. If you are successful in that, proceed to more complex flows. People believe that square driven cavity flow is an option. Right, but it depends upon your goals. If you are to test code based upon somewhat crude "well-established" numerical method, a driven cavity flow is your option. However, if you about to test very accurate method, that's a poor choice. The reason is the singularity at upper corners, i.e. a velocity jump resulting in singular stressesat the upper corners. I am in a great doubt that you can handle this phenomenon properly.

The far better choice (maybe, an ideal choice) is to consider a natural convection in a square enclosure. The problem involves no singularity at all, though requires to take care of buoyanccy forces business. Despite the simplest geometry, the problem is a challenge to your code. Good benchmarked data is provided by Graham de Vahl Davis, "Natural convection of air in a square cavity: a bench mark numerical solution", Internat. J. Numer. Methods Fluids, vol 3 (1983) 249-264. Even though results are obtained via Richardson interpolation, they are quite good up to Ra=10^5.

As for a backfard facing step flow, it also involves a singularity at the step corner, though cfd-people do not often reailize it. However, as believed for moderate Re number flows, the effect of the corner is not crucial. Good references are D.K.Gartling, "A test problem for outflow boundary conditions - flow over a backward-facing step", Internat. J. Numer. Methods Fluids, vol. 11 (1990) 953-967; M.M.Grigoriev, G.F.Dargush, A poly-region boundary element method for incompressible viscous fluid flows, Internat. J. Numer. Methods Engrg., vol. 46 (1999) 1127-1158.

If you do not fail these tests, now you are up to test the performance of your code for the flows in complex geometries. But I'm affraid, there are not too many references I could give. Perhaps, I may want to try move ahead to transient flows, such as unsteady vortex shedding for a flow over a circular cylinder. I cannot recall any good reference for that flow, but maybe, other people could help you.

Regards.

I did lots of comparisons between experimental limner flame (including 2-d Limner flame) and DNS results (Direct Numerical simulation). I did that study in my Ph.D. theses at UNIVERSITY OF WISCONSIN MADISON. The tittle of the theses is (STUDYING REACTING TURBULENT COUETTE FLOW USING DIRECT NUMERICAL SIMULATIONS). You can check my these for more detail.

Thank you for the advice. Actually I am simulating an incompressible without buoyancy effects fluid so the convective flow would not be an option BR

Thank you for your help. Actually I am working without turbulence so the DNS data shouldn't be of great help to make comparisons. BR

I did comparesion for both laminar and turbulant case.