[uli_u]

Hi,

first of all thanks for this great toolset!

I have finished to set up a case to simulate the steady compressible turbulent flow through a manifold (1 inlet, 1 outlet) with rhoSimpleFoam. The goal is to estimate the massflow through the geometry by specifying:

Inlet: Total pressure 1bar, Temperature 293.15K
outlet: Static pressure, 0.9bar

Everything seems be fine but I have still the problem of defining the right BC for this setup.
What should be specified at the inlet to reflect the above BC?

Thanks for any help,

regards
Uli

[maritozzo]

Sorry.. How do you set the rhoSimpleFoam solver. I compiled it but i can't find it in the FoamX case window please help me

[mattijs]

rhoSimpleFoam is probably not configured inside FoamX.

You'll have to edit the files by hand. Just copy and modify an existing tutorial case for one of the other solvers.

[uli_u]

Hi Muzio,

I have edited the files by hand and started the code. The informative error messages helped me to complete the configuration.

I will send you my example by mail. Just put your own mesh in, edit the BCs and start the run by calling rhoSimpleFoam <your_root> tube.

The mesh I put in is just an example, the code will die after a few steps.

Maybe you can help me to find out the BCs for my problem (Totalpressure inlet 1bar, static pressure outlet 0.9bar).

Uli

[uli_u]

Hi,

I have tried to create a FoamX configuration for rhoSimpleFoam. Just untar it under $FOAM_SOLVERS/rhoSimpleFoam which will give you the directory FoamX with all the files needed for your first steps with rhoSimpleFoam.

rhoSimpleFoam_FoamX.tar.gz

As I am very new to Openfoam, there might be some mistakes in there but hopefully there is some expert out there who will fine tune this...

Have fun,
Regards
Uli

[uli_u]

Hi again,

for those who are interested I will add a test case for rhoSimpleFoam. It is a curved tube (meshed with netgen) with an inlet velocity of 50m/s, T=293.15K. Outlet pressure is 1bar. Create a directory under your tutorial directory, call it rhoSimpleFoam and untar the case there.

I have not finished to run this case, after a short time the calculation crashes. Neither decrease of the p-underrelaxation factor helps nor playing with the solver tolerances. Any ideas?



Regards
Uli

[uli_u]

Sorry,

the compressed size of the case is 1.5MB but the board posting limit is 50k. If you are interested, drop me a mail, I will send you the case.

Uli

[mattijs]

Hi Uli,

did you try underrelaxing rho? Just add an entry called 'rho' to the relaxationFactors.

[maritozzo]

Hi everybody , first of all , thank you very much!!..the last file was good.. but now i have other problems.
I have to calculate lift and drag acting on a airfoil, I'm using liftDrag application but it always give me strange results.
For example i always obtain drag coefficient zero for every angle of attack and the lift coefficent is given as a vector while it should be a single value

I just think that it refers to three directions because OpenFoam is a 3d code, but i don't know how to explain myself the drag coefficient

Thank you

[uli_u]

Hi Mattijs,

that was a good hint! I looked into the code and saw the call to rho.relax...I should have looked earlier!

After using the factor for rho the calculation ran a lot more timesteps, but there seems still to be an open issue...it still becomes unstable.

By the way, do you know the default value, when I use no detailed specification for rho-underrelaxatrion, is it 1?

Regards
Uli

[mattijs]

Hi Uli,

I did not converge it fully but it seemed to work with a really low underrelax for k,eps,rho (say 0.05)

Might just be that I haven't run it enough though.

[uli_u]

Hi Mattijs,

thanks for this information. I tried it and the job ran for a long time without getting unstable. I also stopped it, there was no real convergence. I think the problem itself is not a good example, I will think about a better one, maybe using a hex grid.

Nevertheless I still have the feeling that there is something wrong with the turbulence BC - especially epsilon. In several calculations I experienced that using "zeroGradient" works much better than putting a fixed value of epsilon on the inlet. I will investigate this in more detail and collect some pictures showing this behaviour.

Regards
Uli

[giovanni]

Hi all,

can anyone send me Ulrich's test case for rhoSimpleFoam?
The one mentioned on Monday, October 03, 2005 - 04:51 am?

Thanks a lot in advance!

Giovanni

[braennstroem]

Hi all,

I would like to take a look at the test case, too! Is it possible to get a small piece, without the mesh!?

Regards!
Fabian

[lgriffiths]

hi

could somebody email me either the above rhoSimpleFoam test case, or just any test case (for rhoSimpleFoam).

mesh is not important.

this would be a huge help, and much appreciated!

cheers,
Laurence

[jphandrigan]

Are there any test cases kicking around for rhoSimpleFoam? If there are, I'd greatly appreciate it if someone could it to my email address at jhand085@uottawa.ca . Thank you in advance!

[hellorishi]

Hello Everyone,

Even I am in the same boat...
There is no tutorial for rhoSimpleFoam in 1.5 or 1.5.x and I would like to have an example to understand the working BC,system, constant etc.

If anyone has a please help.

THanks
RIshi

[kcjarvis56]

Rishi,
Drop me an email at kcjarvis56 at hotmail(dot)com and I will send you a case.
Kirk

[hellorishi]

Thanks Kirk,

The case is now converging !

[mihir1310]

hello

may i have the test case for rhoSimpleFoam ??




thanx & regards !!!!!!!!!