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October 8, 2019, 04:32 
Limiting volume fraction in interFoam

#1 
Senior Member
Sita Drost
Join Date: Mar 2009
Location: Arnhem, The Netherlands
Posts: 227
Rep Power: 18 
Hi all,
Does anyone have some tips on how to limit the volume fraction in a free surface simulation using interFoam + LTS + semiimplicit MULES? I'm simulating a ship hull at constant (final) velocity, on flat water (OpenFOAM7, Scientific Linux 7). What I've already tried is:
I'd greatly appreciate any help with this! Many thanks, Sita Code:
Starting time loop forces forces: Not including porosity effects Flow time scale min/max = 1, 1 Smoothed flow time scale min/max = 1, 1 Time = 1 PIMPLE: Iteration 1 smoothSolver: Solving for alpha.water, Initial residual = 0, Final residual = 0, No Iterations 1 Phase1 volume fraction = 0.800151 Min(alpha.water) = 0 Max(alpha.water) = 1 MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water Phase1 volume fraction = 0.800151 Min(alpha.water) = 0 Max(alpha.water) = 1 GAMG: Solving for p_rgh, Initial residual = 1, Final residual = 0.00265042, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.00738649, Final residual = 6.70127e05, No Iterations 4 GAMG: Solving for p_rgh, Initial residual = 0.00164859, Final residual = 1.27058e05, No Iterations 5 GAMG: Solving for p_rgh, Initial residual = 0.000374371, Final residual = 3.73205e06, No Iterations 7 time step continuity errors : sum local = 4.17722e06, global = 1.11554e07, cumulative = 1.11554e07 GAMG: Solving for p_rgh, Initial residual = 0.00181009, Final residual = 1.05501e05, No Iterations 6 GAMG: Solving for p_rgh, Initial residual = 0.000606215, Final residual = 4.91912e06, No Iterations 4 GAMG: Solving for p_rgh, Initial residual = 0.000128742, Final residual = 1.28266e06, No Iterations 5 GAMG: Solving for p_rgh, Initial residual = 4.12132e05, Final residual = 4.67321e08, No Iterations 34 time step continuity errors : sum local = 5.256e08, global = 4.63798e10, cumulative = 1.12018e07 PIMPLE: Iteration 2 smoothSolver: Solving for alpha.water, Initial residual = 0.00373314, Final residual = 9.88023e09, No Iterations 194 Phase1 volume fraction = 0.80014 Min(alpha.water) = 0 Max(alpha.water) = 1 MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water Phase1 volume fraction = 0.80014 Min(alpha.water) = 0.994681 Max(alpha.water) = 1.26243 GAMG: Solving for p_rgh, Initial residual = 0.643277, Final residual = 0.0025636, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000239485, Final residual = 2.04436e06, No Iterations 5 GAMG: Solving for p_rgh, Initial residual = 8.292e05, Final residual = 6.51857e07, No Iterations 5 GAMG: Solving for p_rgh, Initial residual = 2.60221e05, Final residual = 2.48377e07, No Iterations 7 time step continuity errors : sum local = 2.63399e05, global = 2.08929e06, cumulative = 1.97727e06 GAMG: Solving for p_rgh, Initial residual = 0.000181122, Final residual = 1.76238e06, No Iterations 6 GAMG: Solving for p_rgh, Initial residual = 3.24913e05, Final residual = 3.01908e07, No Iterations 6 GAMG: Solving for p_rgh, Initial residual = 8.87704e06, Final residual = 8.24178e08, No Iterations 9 GAMG: Solving for p_rgh, Initial residual = 4.60003e06, Final residual = 4.48455e08, No Iterations 7 time step continuity errors : sum local = 9.93412e06, global = 7.66582e07, cumulative = 1.21069e06 PIMPLE: Iteration 3 smoothSolver: Solving for alpha.water, Initial residual = 0.0051518, Final residual = 9.5141e09, No Iterations 193 Phase1 volume fraction = 0.800275 Min(alpha.water) = 0 Max(alpha.water) = 8.08354 MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water Phase1 volume fraction = 0.800276 Min(alpha.water) = 40.6607 Max(alpha.water) = 36.5421 GAMG: Solving for p_rgh, Initial residual = 0.0259583, Final residual = 0.000113245, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000229723, Final residual = 2.13199e06, No Iterations 6 GAMG: Solving for p_rgh, Initial residual = 3.9345e05, Final residual = 3.29743e07, No Iterations 5 GAMG: Solving for p_rgh, Initial residual = 6.93932e06, Final residual = 6.35426e08, No Iterations 7 time step continuity errors : sum local = 3.15815e05, global = 3.83816e08, cumulative = 1.17231e06 GAMG: Solving for p_rgh, Initial residual = 9.03879e05, Final residual = 6.14209e07, No Iterations 5 GAMG: Solving for p_rgh, Initial residual = 6.38855e05, Final residual = 5.87189e07, No Iterations 6 GAMG: Solving for p_rgh, Initial residual = 4.8023e06, Final residual = 4.93757e08, No Iterations 9 GAMG: Solving for p_rgh, Initial residual = 1.0839e06, Final residual = 4.14584e08, No Iterations 2 time step continuity errors : sum local = 7.41179e06, global = 1.83339e07, cumulative = 1.35565e06 smoothSolver: Solving for omega, Initial residual = 6.41347e05, Final residual = 6.31364e06, No Iterations 27 smoothSolver: Solving for k, Initial residual = 1, Final residual = 0.0949203, No Iterations 5 ExecutionTime = 11.67 s ClockTime = 17 s forces forces write: sum of forces: pressure : (307.111 1016.58 1924.9) viscous : (0.437865 1.16819 6.12748) porous : (0 0 0) sum of moments: pressure : (224.651 35978.2 23389.1) viscous : (1.46676 96.1615 17.0622) porous : (0 0 0) Flow time scale min/max = 6.73609e08, 1 Smoothed flow time scale min/max = 6.73609e08, 0.00624496 

October 16, 2019, 04:02 

#2 
Senior Member
Sita Drost
Join Date: Mar 2009
Location: Arnhem, The Netherlands
Posts: 227
Rep Power: 18 
Great, I think I found the solution myself: it looks like my initial conditions were off. I've changed some values, and up to now my simulations are running fine.


January 11, 2023, 02:44 
followup

#3 
New Member
Shai Aser
Join Date: Aug 2015
Posts: 25
Rep Power: 10 
Hi Sita,
what were the changes that you applied to the initial conditions ? Cheers, 

January 11, 2023, 08:04 

#4 
Senior Member
Sita Drost
Join Date: Mar 2009
Location: Arnhem, The Netherlands
Posts: 227
Rep Power: 18 
Hi Shai,
I'm reallyreally sorry, but I've changed jobs in the meantime; I'm in biofluid dynamics now, so I'm no longer using interFoam, and I can't remember what settings I used back then. Reading back my post, I'm pretty annoyed with myself for not writing exactly which initial conditions I changed! As far as I can remember, I gave up using LTS altogether in the end, because it turned out that practically all my simulations would run fine without it. Sorry I couldn't be of more help! Sita 

January 11, 2023, 08:10 
Hi again

#5 
New Member
Shai Aser
Join Date: Aug 2015
Posts: 25
Rep Power: 10 
So you went with regular Euler without compromising the timestep errors ?


January 11, 2023, 09:56 

#6 
Senior Member
Sita Drost
Join Date: Mar 2009
Location: Arnhem, The Netherlands
Posts: 227
Rep Power: 18 
I did indeed, worked for me most of the time (we used a commercial mesher, Hexpress, by Numeca). I never got to fully testing everything in all sorts of cases, though.


January 11, 2023, 10:06 
Thank you

#7 
New Member
Shai Aser
Join Date: Aug 2015
Posts: 25
Rep Power: 10 
Ok thank you very much!, Also for the tip on numeca. I'll check them out


June 5, 2024, 11:58 

#8 
Senior Member
Giles Richardson
Join Date: Jun 2012
Location: Cambs UK
Posts: 102
Rep Power: 14 
thanks  some great suggestions there
for reference its: rDeltaTSmoothingCoeff 0.05; // up to 0.5 rDeltaTDampingCoeff 0.5; Last edited by ufocfd; June 5, 2024 at 13:23. 

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