[fportela]

Hello all,

I have been trying to get a solution for a supersonic turbulent channel flow.

I managed to get sonicFoam working for a Mach number (based on wall temperature) of about 1.5 - t1.png. To achieve this I simply add a momentum source term to the UEqn and eEqn.

When I try to get to M ~ 3 - t2.png - the simulation crashes during laminar-turbulent transition with the following message:

[15] --> FOAM FATAL ERROR:
[15] Maximum number of iterations exceeded
[15]
[15]     From function specieThermo<Thermo>::T(scalar f, scalar T0, scalar (specieThermo<Thermo>::*F)(const scalar) const, scalar (specieThermo<Thermo>::*dFdT)(const scalar) const) const

I am not sure what can be going on, so if you need more information to help me sort this out, just let me know!

Cheers,
Felipe

[immortality]

hi
I didn't get what you mean exactly.
I thought sonicFoam is suitable for all Mach numbers!really its not good for supersonic flows?
If its so why you don't use rhoCentralFoam?i think its certaily appropriate for all regimes of flows.

[fportela]

Originally Posted by immortality

hi
I didn't get what you mean exactly.
I thought sonicFoam is suitable for all Mach numbers!really its not good for supersonic flows?
If its so why you don't use rhoCentralFoam?i think its certaily appropriate for all regimes of flows.

Hi there,

I didn't say sonicFoam doesn't work for supersonic flows, just that I can't manage to get my test case working.

I am aware my original post was a bit vague, but the problem is I don't know where the bug is hiding, though I would expect this to be an issue with the way I set up the case, rather than the solver itself!

I'll give it a go with rhoCentralFoam and see if it helps. Though I'm still curious about why this doesn't work...

UPDATE:

Hi again,

So I took the last time step from the crashed case and let it run with rhoCentralFoam (no momentum source now) and it still crashes (same error message) after some iterations.

[immortality]

Hi
what are your BC's?
could you attach them here?
and why you want to add a source term?and it should be frmo Mach type?
could you attach your modified solver?

[achyutan]

Hi felipe,

To know exactly what is going wrong, try to debug using gdb.
As it is, sonicFoam appears suitable for supersonic flows. I have been successful simulating mach 3 flow (laminar).

regards,

[fportela]

Originally Posted by immortality

Hi
what are your BC's?
could you attach them here?
and why you want to add a source term?and it should be frmo Mach type?
could you attach your modified solver?

Hi,

I have periodic BC's in the stream- and spanwise directions. Upper and lower walls have no-slip (U = 0), constant temperature (T = 300) and zero gradient on pressure.

I have the source term to sustain the flow, otherwise it would just "fade" to rest...

Originally Posted by achyutan

Hi felipe,

To know exactly what is going wrong, try to debug using gdb.
As it is, sonicFoam appears suitable for supersonic flows. I have been successful simulating mach 3 flow (laminar).

regards,

I will try that thanks!

Yes, I wouldn't expect it to be a problem with the solver. I'll let you know if I find what's wrong!

[fportela]

Hi again,

I changed the scheme I was using for div(phid,p) from Gauss linear to vanLeer.

The simulation now seems to be more stable, however my temperature is reaching extremely low values.

I noticed in the tutorials that Gauss limitedLinear 1 is used to discretise this term, shouldn't this affect only the solution for pressure?

Originally Posted by immortality

Hi
could you attach your modified solver?

I sent you a message with the necessary changes

[fportela]

Hi,

So, I tried the Ma ~ 2 test case with rhoCentralFoam. The result is quite different from that of sonicFoam: I get a bunch of shocks that just reflect from one wall to the other - see attached snapshot.

Any ideas? What are the main differences from sonicFoam to rhoCentralFoam that could give such different solutions?!

From what I've read on this types of flows, I would not expect such shocks to develop...

[fportela]

Hi,

In case someone gets a similar issue, just wanted to give the heads up that the viscous term is missing in the energy equation of sonicFoam, in my case this was causing the crash with the temperature decreasing - isothermal wall was extracting energy from the flow, but now heat was produced due to friction

Also, I believe the term

p*fvc::div(phi/fvc::interpolate(rho))

should be

fvc::div(phi/fvc::interpolate(rho), p)