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Spray Evaporation Divergence

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Old   October 8, 2015, 23:26
Default Spray Evaporation Divergence
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Jenna
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I am using Lagrangian-Euler coupling
Attached is a picture of my mesh (~500k cells coarse) and the state of the spray before the solution diverges.

I do not understand why my solution can run for 1200 time steps at 0.5e-8sec and then randomly crash after appearing to run for awhile.

Issues that arise upon divergence:
Eulerian of liquid's gas phase and air velocity shoots up high. Lagrangian particle velocity also shoots up. Temperature tries to go below my minimum reference value of 200k (when the chamber is at 900k and liquid initially at 363K).
convective courant number is okay until this divergence.

I also experience what looks like a reversed flow at my inlet.
The inlet for the eulerian phase = velocity inlet at 0.01 m/s of air (negligible).
Inlet defined as a part injector, so it uses the inlet surface as its starting point. It almost seems like the injector has re circulation around it into the inlet.. which is odd and noticeable as reversed flow vectors as well as negative pressure scalar.

PS: my injection velocity is 55 m/s, so you can already see in the second image that it is beginning to climb - although it did not do this in any of the previous time steps. Simulation is run as RANS, plan to use LES after this works

Any thoughts or suggestions are welcome!!
Attached Images
File Type: png mesh1.PNG (20.4 KB, 33 views)
File Type: png scalar1.PNG (45.4 KB, 47 views)
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Old   October 12, 2015, 03:03
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Mark Olesen
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This is really a case that you have to discuss with your support, since there are many details that can be a factor here.
Assuming your spray is multi-component, version-9.06 is the minimum version that you should be using. The temperature decrease is probably caused by the vaporize spray-wall interaction. You will also need to check that your specified (or implied) latent heat of vaporization is something sensible. There are a number of other things that can also be a factor, but this is impossible to diagnose via the forum. You will definitely need to do this yourself, with the friendly help of your support.

Cheers,
/mark
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