Troubles with the dpm model
 

Hi, I'm Marco Antonelli and I am researcher at the University of Pisa.

I set up a cluster for parallel computing using Fluent 6.3 and I'm simulating the injection of gasoline inside an engine cylinder. When I used a single pc it ran all ok, but since I've been trying using this cluster, I've this trouble with the injection: after some time steps, the calculation is blocked at the dpm injection advance and does nor proceed, neither giving any error.

Anyone had the same trouble than me?

Thanks

Marco

Re: Troubles with the dpm model
 

Are you running a multiphase simulation?

Re: Troubles with the dpm model
 

My simulation is a discrete phase one. I'm injecting gasoline inside an engine cylinder.

Re: Troubles with the dpm model
 

The reason I asked, to quote the 6.2 manaul..

"When tracking particles in parallel, the DPM model cannot be used with any of the multiphase flow models (VOF, mixture, or Eulerian { see Chapter 23: Modeling Multiphase Flows) if the shared memory option is enabled (Section 22.11.9: Parallel Processing for the Discrete Phase Model). (Note that using the message passing option, when running in parallel, enables the compatibility of all multiphase ow models with the DPM model.)"

Re: Troubles with the dpm model
 

No, any of these model was used. Moreover, the message passing option is currently used. The strange fact is that the calculation start, but stops after a random number of time steps without an apparently cause.

bye

Marco

Re: Troubles with the dpm model
 

Do you use wall-film model ? The same happens also to me

Re: Troubles with the dpm model
 

Yes, I do. I'm trying to change some parameters about numerics, but I've still got very few results...

If I'll discover something interesting, I'll post it.

bye

Marco

Re: Troubles with the dpm model: collision probl ?
 

I am simulating injection of liquid ammonia (tb=-33 Deg) in tha atmosphere (air + water vapour, 80% humidity). The solver is pressure-based, usteady. Problem time 900 sec, time step=0.25 sec, 150000 cells, 6 node parallel computer. DPM: injected 5 parcels per particle time step=0.05 sec. coupled, unsteady. Boundary: wall-film. I had very big problems: temperature & pressure out of the limits, dpm concentration > 10000kg/m3, extreme jumps in the mass sources, evaporation of droplets with temp. below dew point (??), crash. Despite I eliminate problems in crashes (re-writing the mass & heat transfer routines), FLUENT enters in an infinite loops after the message Advancing DPM Injection ...

I remove the problem by switching off the droplet-collision option !!!

Try it. Gian

PS: now I use wall-jet because with wall-film I had problems in parallel processing like "lost x particles in node y" and consequent mass error

Re: Troubles with the dpm model: collision probl ?
 

However, coalescence is a very important matter while simulating injections (especially gasoline injection)...

I have the same qusetion, how did you solve it?
think you!
:confused:

Hi All! Is the wall-film model compatible with combustion models in Fluent?

Thanks a lot in advance!

Marta