how to justify that my numerical predictions are correct
how to justify that my numerical predictions are correct when i don't have experimental results. what kind of validation tests can be performed? thanks in advance.. :)

You could simulate a known flow pattern and compare with bench mark solutions.
Bench mark flow solutins can be found in, Schafer, et al, "Bench maek computations of laminar flow around a cylinder" Notes on numerical fluid mechanics, 52, 547566 (1996) Oosterlee et al, "Benchmark Solutions for teh incompressible NavierStokes Equations in general co0ordinates on staggered grids", International Journal for numerical methods in fluids, 17,30321, (1993) Or if you are working with compressible flows, I'm sure you can find a similar document that is more appropriate. 
thanks Mr. dandalf ..
I did compared my simulation results with some standard benchmark problem. but the original problem which i am trying has no experimental results available in liturature. Is there any other check i can do before publication? 
The only other think I can think of is to double check conservation of mass throughout the simulation, if mass is conserved both locally and globaly throughout the simulation, then the flow must at least be physicaly plausable.

Hi Dan
In the above query u have metioned verify the conservation of mass,does that mean the mass flow rate value @ inlet and outlet boundaries

Hi Dan
In the above query u have metioned verify the conservation of mass,does that mean the mass flow rate value @ inlet and outlet boundaries
Quote:

but in finite volume method we are inherently solving conservation form of equations. This means if mass residue is sufficiently small, will it automatically satisfy both local and global conservation of mass??
whether mass conservation implies to momentum conservation also? 
If you are working with the compressible form of the conservation equatiosons both should already be satisfied.
My point was mearly that if checks reveal that either are not satisified then the result must be incorrect. you can double check conservation of momentum for each cell buy confirming, http://www.cfdonline.com/Forums/vbL...ad0727c21.gif for each direction. Of course if you are using a non cartesian mesh then you will have to adjust the equations. 
Thanks to all..

tushar,
One general practice to ensure cfd results are meaningful is  monitoring the residual convergence behavior of a physical variable inside the flow domain to one's satisfaction. However, the choice of the variable and location for its monitoring varies from problem to problem and so it must be made intelligently; otherwise it may not help. Futher, it is always advisable to put some extra effort and conduct i) mesh independence study ii) analyse turbulence models effectiveness iii) check numerical diffusion iv) check in results  numerical bounds of all variables (should be consistent to specified BCs)  any gradients in flow correlate to local geometry variations or other natural phenomena v) recheck if results appeal to commonsense Having done all this, you will be in a position to publish; but more importantly have the courage to defend and receive critical reviews. Best luck S 
All times are GMT 4. The time now is 05:35. 