Free Surface Ship Flow

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 October 24, 2014, 01:42 #281 Member   Sachin Join Date: Aug 2014 Location: India Posts: 84 Rep Power: 11 I am working on a ship hull using LTSInterFoam. My simulations went well in the beginning until after around 15000 timesteps, the force values boomed up. It was around 9000 N and all of a sudden it shooted up to 4e08 +. Can anyone tell me what could be the possible reason. The hull is that of a barge.

 December 30, 2014, 23:43 Flow around ship hull #282 Member   Sachin Join Date: Aug 2014 Location: India Posts: 84 Rep Power: 11 Iam using Open Foam 2.3.1. Iam trying to simulate a flow around ship using LTSInterFoam. I encountered with the below error. can anyone help me out with this? Time = 0.001 Flow time scale min/max = 4.879e-94, 1.174e-20 Smoothed flow time scale min/max = 4.879e-94, 3.15e-91 Damped flow time scale min/max = 4.879e-94, 3.15e-91 PIMPLE: iteration 1 smoothSolver: Solving for alpha.water, Initial residual = 0.001018, Final residual = 5.476e-07, No Iterations 2 Phase-1 volume fraction = 0.6114 Min(alpha1) = -1.91e-08 Max(alpha1) = 2.414 Applying the previous iteration compression flux MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water Phase-1 volume fraction = 0.6114 Min(alpha1) = -3.396e-05 Max(alpha1) = 2.365 smoothSolver: Solving for alpha.water, Initial residual = 0.001111, Final residual = 5.757e-07, No Iterations 4 Phase-1 volume fraction = 0.6114 Min(alpha1) = -1.565e-08 Max(alpha1) = 3.426 Applying the previous iteration compression flux MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water Phase-1 volume fraction = 0.6215 Min(alpha1) = -0.418 Max(alpha1) = 10.33 smoothSolver: Solving for alpha.water, Initial residual = 0.162, Final residual = 0.0001505, No Iterations 5 Phase-1 volume fraction = 0.617 Min(alpha1) = -0.0001251 Max(alpha1) = 4.383 Applying the previous iteration compression flux MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water Phase-1 volume fraction = 0.6113 Min(alpha1) = -12.64 Max(alpha1) = 4.254 smoothSolver: Solving for alpha.water, Initial residual = 0.2362, Final residual = 0.0002031, No Iterations 5 Phase-1 volume fraction = 0.6144 Min(alpha1) = -0.2591 Max(alpha1) = 5.291 Applying the previous iteration compression flux MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water Phase-1 volume fraction = 0.615 Min(alpha1) = -7.501 Max(alpha1) = 25.08 smoothSolver: Solving for alpha.water, Initial residual = 0.2808, Final residual = 0.0002388, No Iterations 5 Phase-1 volume fraction = 0.618 Min(alpha1) = -0.1152 Max(alpha1) = 6.153 Applying the previous iteration compression flux MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water MULES: Correcting alpha.water Phase-1 volume fraction = 0.6383 Min(alpha1) = -7.343 Max(alpha1) = 57.66 smoothSolver: Solving for omega, Initial residual = 2.776e-05, Final residual = 1.459e-08, No Iterations 6 bounding omega, min: -1.657e+05 max: 2.675e+07 average: 9843 smoothSolver: Solving for k, Initial residual = 0.0004899, Final residual = 1.194e-08, No Iterations 9 bounding k, min: -0.007236 max: 5.074 average: 0.00445 smoothSolver: Solving for Ux, Initial residual = 0.5367, Final residual = 2.726e-18, No Iterations 3 smoothSolver: Solving for Uy, Initial residual = 0.6717, Final residual = 4.852e-20, No Iterations 3 smoothSolver: Solving for Uz, Initial residual = 0.7993, Final residual = 9.98e-34, No Iterations 3 #0 Foam::error:rintStack(Foam::Ostream&) at ??:? #1 Foam::sigFpe::sigHandler(int) at ??:? #2 in "/lib/x86_64-linux-gnu/libc.so.6" #3 double Foam::sumProd(Foam::UList const&, Foam::UList const&) at ??:? #4 Foam::PCG::solve(Foam::Field&, Foam::Field const&, unsigned char) const at ??:? #5 Foam::GAMGSolver::solveCoarsestLevel(Foam::Field&, Foam::Field const&) const at ??:? #6 Foam::GAMGSolver::Vcycle(Foam::PtrList const&, Foam::Field&, Foam::Field const&, Foam::Field&, Foam::Field&, Foam::Field&, Foam::Field&, Foam::Field&, Foam::PtrList >&, Foam::PtrList >&, unsigned char) const at ??:? #7 Foam::GAMGSolver::solve(Foam::Field&, Foam::Field const&, unsigned char) const at ??:? #8 Foam::fvMatrix::solveSegregated(Foam::dict ionary const&) at ??:? #9 Foam::fvMatrix::solve(Foam::dictionary const&) at ??:? #10 at ??:? #11 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #12 at ??:? Floating point exception (core dumped)

 December 31, 2014, 03:26 #283 Member   vincent Join Date: Apr 2011 Posts: 45 Rep Power: 15 Hi Sachin Could you send more details about your case (fvScheme and FvSolution dict)... It's difficult to find the problem withtout this. Have you check your mesh? May be it's due to bad mesh. Best regards Vince

 March 31, 2015, 06:30 Trim for the hull (Positioning the geometry in the Domain) #284 Member   Sachin Join Date: Aug 2014 Location: India Posts: 84 Rep Power: 11 Has anyone tried simulation of a vessel with a trim.?? I would like to simulate a ship with a trim of 7 degrees. Is there anyone who can help me out with this?

March 31, 2015, 06:34
#285
New Member

saman
Join Date: Apr 2012
Posts: 4
Rep Power: 14
Quote:
 Originally Posted by Sachin m Has anyone tried simulation of a vessel with a trim.?? I would like to simulate a ship with a trim of 7 degrees. Is there anyone who can help me out with this?
yes, I already considered trim on my simulations. what is exactly your problem?

 April 2, 2015, 02:13 #286 Member   Sachin Join Date: Aug 2014 Location: India Posts: 84 Rep Power: 11 is it possible to give a trim to the hull in open foam itself. That is, if i have a geometry can i simulate it with different trim using that same geometry by positioning it at an angle using openFoam. Is there a way to do that in OpenFoam.(Other than creating diffferent geometries in a cad software)

 April 2, 2015, 02:28 #287 Member   Sachin Join Date: Aug 2014 Location: India Posts: 84 Rep Power: 11 And also i would like to know how to get the wetted surface area in paraview

 April 2, 2015, 02:29 #288 Member   Sachin Join Date: Aug 2014 Location: India Posts: 84 Rep Power: 11 n thanx for the reply saman

 April 2, 2015, 03:34 #289 New Member   romainRH Join Date: Jul 2012 Posts: 24 Rep Power: 13 Hi Sachin M, Yes you can move the boat with openfoam. You can take a look at interDYnFoam or dynamicFvMesh For the wetted surface you can try to use a Quality filter to compute surfaces then use calculator to multiply by the volume fraction Sachin m likes this.

April 2, 2015, 04:32
#290
New Member

saman
Join Date: Apr 2012
Posts: 4
Rep Power: 14
Quote:
 Originally Posted by Sachin m is it possible to give a trim to the hull in open foam itself. That is, if i have a geometry can i simulate it with different trim using that same geometry by positioning it at an angle using openFoam. Is there a way to do that in OpenFoam.(Other than creating diffferent geometries in a cad software)
Sachin m

here is the command I use for rotating STL file.
surfaceTransformPoints 1.stl 2.stl -yawPitchRoll "(0 -5 0)"
To see the free surface around your hull you should to use Quality filter as romainRH said, put the alpha1 eqaul to 0.5.

Regards,
Saman

 April 7, 2015, 09:09 #291 New Member   Join Date: Feb 2015 Posts: 18 Rep Power: 11 Hi Everyone, I'm currently trying to make a simulation working for a flow around a motorboat (with free surface and so one) using inter foam. The reason I use inter foam instead of LTSInterFoam is because I want to go for dynamic simulation of the boat with interDyMFoam later on. For now, I've been able to run a proper simulation of my boat with LTSInterFoam but I'm unable to do the same with interFoam. I've asked questions in some other threads, got some useful answer but for now nothing is working. Does anyone have a bit of experience and would agree to share his source file (BC fv Schemes, fv solution controlDict) with me so as I have a working example. Obviously I don't need geometry since I understand it may be confidential... If you people have any tricks or tips I'll be more than happy to hear your advice since I'm a wee bit desperate... Regards Jordan

 April 7, 2015, 09:13 #292 New Member   romainRH Join Date: Jul 2012 Posts: 24 Rep Power: 13 Hi jojosaxo Can you be more precise about your problem? When does it occur? Does it start or crash before the first iteration?

 April 7, 2015, 09:33 #293 New Member   Join Date: Feb 2015 Posts: 18 Rep Power: 11 The simulation start normally, it only crashes after a few hundred of iteration. Generally, pressure is increasing. I also often see time step decreasing rf several order that means that velocity is exploding as well.

 April 7, 2015, 09:35 #294 New Member   James hakes Join Date: Aug 2013 Posts: 5 Rep Power: 12 Try mapfields from your LTS sim and use as initial conditions

 April 7, 2015, 09:55 #295 New Member   romainRH Join Date: Jul 2012 Posts: 24 Rep Power: 13 Also check courant number. I think the most relevant scheme is for the freeSurface transport equation. I use SuperBee for alpha1 (of.v2.2). i think it is not the same name now :/

 April 7, 2015, 10:43 #296 New Member   Join Date: Feb 2015 Posts: 18 Rep Power: 11 I did not get your answer about the "relevant scheme"... I've already tried to initialize with LTSinterFoam but if I carry on the computation with interFoam it blows up...

 April 7, 2015, 10:58 #297 New Member   romainRH Join Date: Jul 2012 Posts: 24 Rep Power: 13 I have found that in fvscheme, the parameter that most influence the behaviour of the simulation, is the numerical scheme used for solving the transport equation of volume fraction. Look for divSchemes and div (phi, alpha) in fvSchemes Is it clear now?

 April 7, 2015, 11:13 #298 New Member   Join Date: Feb 2015 Posts: 18 Rep Power: 11 Yes I got it! Unfortunately the scheme you're talking about is not available anymore... Would you be ok to share your file? Thank's a lot!

 April 7, 2015, 11:47 #299 New Member   romainRH Join Date: Jul 2012 Posts: 24 Rep Power: 13 I don't have it now i have to look in my old work. But SuperBee is still available in v2.3.1 ^^

 April 10, 2015, 01:50 #300 Member   Sachin Join Date: Aug 2014 Location: India Posts: 84 Rep Power: 11 Thank you romainRH and saman for your valuable replies. I would try out and let you know. In between is there anyone who has tried incorporating wave conditions in to the ship simulation using LTSInterFoam?

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