InterPhaseChangeFoam: trying to simulate cavitation phenomena inside of nozzle
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Dear Foam Users,
I am trying to simulate cavitation phenomena inside of nozzle and using interphasechangefoam. As you know that there are 3 transport models (Merkle, Kunz and Sauer) I have tried all of these 3 models with kwSST turbulence model however i have problems with the obtaining of cavitation region as follows; 1. If i set the initial cond. according to Velocity as follows: ==> 0/U Code:
internalField uniform (0 3.104 0); Code:
internalField uniform 1e5; 2.if i set the initial cond. according to pressure as follows: ==>0/P Code:
internalField uniform 1e5; Code:
internalField uniform (0 0 0); In addition; For interphasechange solver (or more generally if we try simulation multiphase with mass transition which initial condition setting is more logical; pressure or velocity based? Thanks in advance... |
Sorry I forgat to say that initial velocity and pressure values are taken from the experiment...
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Hi Baris,
are you still working on that issue? regards Alex |
Hi Alex,
Yes I am still working about same topic. Do you have any question? B |
I didn't realize, that you are sure pretty experienced, so I assume that you aren't stuck at the same place like one year before... :rolleyes:
I think i wanted to help you yeserday. I currently try different things with InterPhaseChangeDyMFoam, but my problem is more a lack of c++ knowledge... thanks for your offered help and sorry for the unnecessary disturbance. ;) regards Alex |
Thank you for your kind consideration. Yes, i faced stability problem for a long time. However, finally i fixed and solved the problem.
I think that C++ is main problem for all new beginners. This can be also fixed in time with hard work ;) Please keep in touch and let me know about your challenge and brief findings in InterPhaseChangeDyMFoam. BR Baris |
Hi people,
I have seen you are using interPhaseChangeFoam to simulate cavitation phenomena inside nozzle. Actually I'm working in this topic too. I have a question about this solver I hope you could answer me: interPhaseChangeFoam works with a hydrostatic pressure definition, isn't it? Did you do your simulations with this pressure definition or did you do any change? And... to make this change, is it necessary to modify the pEqn.H file, or is there another easy way? Regards, Alvaro. |
Hi Alvaro,
did you try to work with the cavitatingBullet tutorial multiphase/InterPhaseChangeFoam/cavitatingBullet ? You can change the geometry and customize it for your case. regards Alex |
Hi Alvora,
Here hydrostatic pressure definition is just a kind of trick to simplify the boundary conditions and also increase the stability when the gravity should be considered. I just didnt understand why you want to change it? Finally, solver also calculate the total pressure as calculated and indicated in "CreateFields.H" P=p_rgh+rho*gh. As Alex said you can look at cavitatingBullet tutorial or last year i attended to CFD open course in Chalmers and already written a tutorial which explains cavitatingFoam and interPhaseChangeFoam for nozzle cavitation. You can also download and check it here: https://www.researchgate.net/publica...njector_Nozzle BR. Baris |
Hi,
I've seen your work Baris, and looks fine. I've tried to implement the code but I have a problem in the step to compile "phaseChangeTwoPhaseMixtures". The terminal returns me the following error and I don't know how to solve it. Code:
alvaro@AlvaroPC:~/OpenFOAM/alvaro-2.3.0/applications/solvers/multiphase/TransportCavitatingFoam/phaseChangeTwoPhaseMixtures$ wmake Make/files Code:
phaseChangeTwoPhaseMixture/phaseChangeTwoPhaseMixture.C Code:
Kunz/Kunz.C Code:
# 1 "options" Thanks. |
Hi again,
I ran the simulation with interPhaseChangeFoam and I obtained high negative pressure values. I think it's wrong, but why does this happen? How can I avoid that? Regards |
Hi alvaro,
negativ pressure values aren't bad if they don't exceed -1e+05 Pa (-1bar) . I never gave it a thought, because I think its effective pressure and not absolute pressure plotted by paraView. regards Alex |
I think I have to correct myself.
I read in some posts, that p is the absolute pressure in InterPhaseChangeFoam, so you have discovered really an error. Edit: Now I have to correct/clarify my correction. My first suggestion Quote:
Quote:
As read here: http://www.cfd-online.com/Forums/ope...m-error-2.html Quote:
p_rgh is the relative/effective pressure that is plotted by paraFoam rho*gh is the atmospheric pressure so everything is fine in my computation. ;) regards Alex |
Hello Alex,
I'm not completely sure that you are right.You can find something about the negative pressure issue in this tutorial:http://www.tfd.chalmers.se/~hani/kur...lenceModel.pdf page 16 Regards Jiří |
Hi Jiri,
In that tutorial he also said that negative pressure is unrealistic condition. Quote:
BR Baris |
Quote:
Yes, I agree with this statemt. It was reaction to the last post. I have to confess that I read the thread only cursorily. On the other hand I thought that the tutorial could be useful. Have a nice day! Regards, Jiří |
Hi Shipman,I just cant't understand why the pressure could below 0,some people say that may be induced by compressible property,can you explain more details? thanks a lot
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regarding the p_rgh value and saturation pressure value
Dear all,
Sorry for reopening this discussion. I'm working on pump sump models and trying to model the cavitation at the suction side of the pump. I found in this forum that pressure should be applied as absolute and hence 1e5 value is used in tutorial I have following doubt, Since we have to input p_rgh value instead of p, then it should be 1e5-(1000(water)*-9.81*height) right instead of just 1e5? |
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