mixture model for cavitation
I have a hydrofoil and i study the cavitation which is showed on it. I use the spalartallmaras turbulent model and the mixture model for cavitation.
When i run the hydrofoil without cavitation (i dont use mixture model), i take a converge solution, but when i run it with the mixture model i take diverging solution after some iterations (and say: diverge xmom). What must i attend ? 
Hi there,
If you want I can send you several papers I've published on cavitation modeling in Fluent. Just send me an email. By Mateus 
my mail is : mech5190@upnet.gr
Send me these paper which tell me. 
Hi,
I am currently modeling a marine turbine and I am studying the cavitation effects on the turbine. I am facing the same issue. My first simulations ran very well without cavitation (without the mixture model). But when I try with the mixture model, I get a divergence problem : divergence in AMG solver. I tried to reduce the URF, but it does not work. I tried segregated and coupled solver, but I got the same problem. I am running out of ideas. Did you finally solved this problem and how ? Thank you Jeremie 
Hi,
I got some nice results using fluent to model cavitation... you can find them in paper: Experimental evaluation of numerical simulation of cavitating flow around hydrofoil Original Research Article European Journal of Mechanics  B/Fluids, Volume 24, Issue 4, JulyAugust 2005, Pages 522538 Matevž Dular, Rudolf Bachert, Bernd Stoffel, Brane Širok Give me you're mail so that I'll contact you directly... Best regards, Matevz 
Hi,
Thank you for your answer. As I wrote, I want to simulate a marine turbine in a steady water flow with ANSYS FLUENT 12. I study the performances of the turbine. My first simulations ran very well. I reached converged solutions for three different rpm. The conditions were :  steadystate, pressurebased solver  NO multiphase model  Realizable ke with wall treatment (I used an hybrid mesh with a fine prism boundary layer around the blades)  Velocity inlet, pressure outlet, rotating walls  SIMPLE pressurevelocity coupling, second order discretization With these results, I figured out that I could not ignore the cavitation effects. So I tried the same simulation with the mixture model (with the slip velocity disabled). But the solution diverged after 10 iterations (divergence detected in AMG solver). Then, I tried with the Volume Fraction equation disabled. I thought I was going to get the same results I got with my first simulations, but I still got a divergence detected in AMG solver. I reduced the URFs, I chose a coupled pressurevelocity scheme, a firstorder discretization. But I always got the same divergence issue. I really don't understand why I cannot reach a converged solution with the mixture model, even with the VF equation disabled. Thank you in advance for your help. Regards, Jeremie 
Hi,
I still have difficulties with the cavitation model in Fluent 12, and to get a converged solution with the cavitation model activated (Full Cavitation Model). So I wanted to have a converged solution without the mixture model, and to be sure of the pressure field. I use a uniform velocityinlet condition, a pressureoutlet condition, and the domain is closed by walls where a slip condition is set. The operating pressure is set to 0, and I set the static pressure outlet in order to get a total pressure corresponding to the depth of the turbine. I don’t change the default value for the vaporization pressure (2367.8 Pa). I have some doubts concerning these settings because I read somewhere that the operating pressure should be set equal to the ambient pressure, and the vapour pressure equal to 80000Pa. Does anyone have some advice about these pressure settings? Thank you Jeremie 
Hi,Matevz Dular
i got the same problem when i simulated a model Francis turbine with full cavitation. my email is liwan@whu.edu.cn and send me some papers Best regards Li wan 
Hi,Jeremie
how about your simulation? i have the same issue about the cavitation. we can communicate with each other and get some solutions. my email is liwan@whu.edu.cn best regards Li Wan 
Hello Matevz,
I am trying to simulate cavitation in journal bearings using the mixture model. Could you send me your papers on cavitation modeling (I may get some help on how to setup my cavitation model in FLUENT). My email is yousufmansoor@hotmail.com Cheers, Yousuf 
Hi Yousuf,
You can downoload all my papers from my web page: www2.arnes.si/~mdula or just type matevz dular in google to find my page. Best regards and good luck with your work... Mateus 
Hi,
let us concentrate only on the cavitation and not the full cavitation (gas cavitation) which occurs in many industrial applications and needs considering dissolution and absorption of non condensing gas. First of al: use either the schnell sauer or ZwartBelarmi. Mixture model without slip: bubbles won't grow up since the flow is high turbulent and the vapor bubbles are assumed then to flow as quick as the carrier phase. Start with very tiny time steps: Cavitation is very quick process, mechanic driven and numerical expensive. The most simulations i carried out the time step was below 1e4/1e5. Please do not the singhal mode which depicts one aspect of the ful cavitation model since it's highly instable and is based on old numerical inplementation 
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