Developing Direct Simulation Monte Carlo and I have problem

[Noh-hoon Lee]

Please understand my low command of English.

I'm developing Direct Simulation Monte Carlo and I'm now validating.

To validate my DSMC code, I'm checking the viscosity in Couette Flow.

Simulation Condition is, Kn = 0.0056(Near Continuum) and Gas is Nitrogen, Temperature is 273K.

Nitrogen viscosity is approximately 1.656e-5 but in my simulation, viscosity is now 1.5e-5.

I can't understand why viscosity is lower than experimental value.

I have thougt it is caused by cell size. But I set the cellsize as half or quarter of mean free path.

It is common value of DSMC simulation.

I'm now wating for your advice :)

 

[asym]

In my opinion, instead of experiment, you should compare your results to someone else's simulation done with the same parameters. Search for some open source DSMC programs and use them as a benchmark.

 

[Noh-hoon Lee]

I try to find some thesis or simulation data but It was hard to find that.
I found DSMC-IP data but I need DSMC data. DSMC data is too hard to find.
So I try to compare my result to exact viscosity

 

[asym]

OpenFoam has a DSMC solver in it.

http://www.openfoam.com/features/standard-solvers.php#DSMCSolvers

However I don't know how difficult it is to make it work.

I am not familiar with this kind of simulations (I do ordinary molecular MC) so maybe it's something totally different from what you're looking for.

 

[Noh-hoon Lee]

Thank you for your help. I'll try to use OpenFoam and to modify the code to get the viscosity data. You show me the way