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#1 |
New Member
Join Date: Aug 2011
Posts: 3
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Hello, I am using dsmcFoam to simulate a cold gas thruster that vents to a near vaccum. I used the supersonic wedge as my basis and adjusted the initial conditions for my problem. The geometry is just three concentric cylinders of growing diameter. The first cylinder having a inlet on its face and the final cylinder having an outlet on all faces except the area that interests with the middle cylinder. I am able to intialize and run the program, but when it comes to running the dsmcFieldsCalc, it breaks down. This is the error message that I recieve when I try running the command: Small value (min(mag(rhoNMean)) [0 -3 0 0 0 0 0] 9.99e-301) found in rhoNMean field. Not calculating dsmcFields to avoid division by zero. Has anyone come across this problem before and can explain how they fixed this? Thanks, yc
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#2 |
Senior Member
Vincent RIVOLA
Join Date: Mar 2009
Location: France
Posts: 283
Rep Power: 18 ![]() |
I can't help you much since I have the same problem.
Did you find a solution? |
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#3 |
New Member
Join Date: Feb 2013
Posts: 1
Rep Power: 0 ![]() |
Yellow / vinz this happens in the very low density regions. (In paraview you can identify these cells using threshold whilst viewing the density fields.)
I had a similar problem and used some scripting as a quick fix. If you havent resolved the issue since your last message, post your case and i'll check if i can help. |
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#4 |
Senior Member
Vincent RIVOLA
Join Date: Mar 2009
Location: France
Posts: 283
Rep Power: 18 ![]() |
Hello T-1,
The problem looks to be related to the fact that we are simulating wedges which apparently not handled by dsmcFoam so far. |
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#5 |
New Member
murali
Join Date: Feb 2013
Location: pondicherry
Posts: 10
Rep Power: 13 ![]() |
hello T-1
i am also facing same problem, Small value (min(mag(rhoNMean)) [0 -3 0 0 0 0 0] 9.99e-301) found in rhoNMean field. Not calculating dsmcFields to avoid division by zero. calculating averages can you help me to solve this error |
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#6 |
Member
Join Date: Jul 2013
Posts: 62
Rep Power: 13 ![]() |
Hello, does anybod fix this problem and have a solution?
Please answer if you know it. Best regards CFDNewbie147 |
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#7 |
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,978
Blog Entries: 45
Rep Power: 128 ![]() ![]() ![]() ![]() ![]() ![]() |
Greetings CFDNewbie147,
I'm sorry to say that everyone who asked about this on this thread, did not follow the basic instructions on http://www.cfd-online.com/Forums/ope...-get-help.html The very most basic question is: what were the exact steps that were taken to reach that message? Beyond this:
Best regards, Bruno
__________________
Last edited by wyldckat; February 18, 2014 at 15:14. Reason: see "edit:" | Rephased from "This thread" to "The following thread" |
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#8 |
Member
Join Date: Jul 2013
Posts: 62
Rep Power: 13 ![]() |
Hello Bruno,
thank you for answering. 1. I use the OpenFOAM version 2.2.1 2./3. I use the the wedge15Ma5 dsmc tutorial as base for my simulations I took the simulation case and adapted it to an extern built mesh which I've imported to OpenFOAM without any failures in checkMesh. It looks like a windtunnel with inlet, outlet, walls and the geometry inside the windtunnel. As in the wedge15Ma5 tutorial i made the sides of the windtunnel to the "flow" region with "patch" and the geometry itself as the "obstacle". With this i do the dsmcInitialise where particles are inserted and then I do dsmcFoam. But when doing the dsmcFieldsCalc there's always the mentioned failure message. 4. It's "only" a windtunner with an object inside it. So yes I can or anybody can built it quickly. (e.g from motorbike tutorial) I hope this will be enough information. Best regards CFDNewbie147 |
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#9 |
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,978
Blog Entries: 45
Rep Power: 128 ![]() ![]() ![]() ![]() ![]() ![]() |
Hi CFDnewbie147,
I'm not very familiar with these solvers. But I've found the file "discreteMethods/dsmcFoam/README" in the "tutorials" folder, which has some crucial information on what fields are used by this solver. Beyond this, please provide a simple case that reproduces this problem. That way it'll take me considerably little time to try and diagnose the problem. Otherwise, don't expect me to give any answers on this before July 2014 ![]() Best regards, Bruno
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#10 |
Member
Join Date: Jul 2013
Posts: 62
Rep Power: 13 ![]() |
Hello again,
I think I solved the problem. When you look at the file "discreteMethods/dsmcFoam/README" as you've said: [...]"setting zeroGradient boundary conditions on walls" [...] for iDof, internalE, linearKe, momentum, rhoM and rhoN. I changed the originally "calculated" for my wall to zeroGradient and the dsmcFields-calculation works and i get overallT, UMean and so on... I don't know exactly why there was calculated because these parameters are only relevant for cell data but now it works. If anybody does have some hints, please answer ![]() Best regards CFDNewbie148 |
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#11 | |
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,978
Blog Entries: 45
Rep Power: 128 ![]() ![]() ![]() ![]() ![]() ![]() |
Hi CFDnewbie147,
Quote:
Bruno
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Tags |
calc, dsmc, dsmcfieldscalc, dsmcfoam, error |
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