
[Sponsors] 
June 18, 2014, 08:40 

#261 
New Member
Ali
Join Date: Oct 2013
Posts: 25
Rep Power: 3 
Hi Jianxi Yao,
Thank you very much for your response. I have attached the link of case files here. Please check it and let me know your advice. I appreciate your kind help. https://www.dropbox.com/s/e83368jwb3nz7f6/wigley.zip Best regards, Ali 

June 18, 2014, 09:35 

#262  
New Member
Jianxi Yao
Join Date: Apr 2011
Posts: 15
Rep Power: 6 
Quote:
I found some tutorials on the 7th OF workshop. See below: http://www.openfoamworkshop.org/2012/OFW7.html Please see the title named Marine Hydrodynamics by E. Patterson. You could download some useful materials via the link. My settings are very similar with E. Patterson. If you still feel unhelpful. I can send you my case files later (not now). Good luck. Jianxi Yao 

July 3, 2014, 17:20 

#263 
New Member
Ali
Join Date: Oct 2013
Posts: 25
Rep Power: 3 
Hi Jianxi Yao,
Good morning. I have tried several settings in fvschemes and fvsolutions including Prof. E. Patterson settings to calculate the resistance using InterDyMFoam. But the results are not satisfactory still now. please note that, I did not add any boundary layer or free surface mesh, just mesh around the hull only. I have spent a lot of time,but no outcome. I am little bit puzzled now. I appreciate any kind of help. Thank you Ali 

July 9, 2014, 09:24 

#264  
New Member
Jianxi Yao
Join Date: Apr 2011
Posts: 15
Rep Power: 6 
Quote:
My settings in fvschemes and fvsolutions are /** C++ **\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 2.3.0   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default Euler; } gradSchemes { default Gauss linear; limitedGrad cellLimited Gauss linear 1; } divSchemes { div(rhoPhi,U) Gauss linearUpwindV grad(U); div(phi,alpha) Gauss vanLeer; div(phirb,alpha) Gauss interfaceCompression; div(phi,k) Gauss upwind; //Gauss linearUpwind limitedGrad; div(phi,omega) Gauss upwind; //Gauss linearUpwind limitedGrad; div((muEff*dev(T(grad(U))))) Gauss linear; } laplacianSchemes { default Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } fluxRequired { default no; p_rgh; pcorr; alpha.water; } and /** C++ **\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 2.3.0   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSolution; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solvers { "alpha.water.*" { nAlphaCorr 1; nAlphaSubCycles 2; cAlpha 1; icAlpha 0; alphaOuterCorrectors yes; MULESCorr yes; nLimiterIter 100; alphaApplyPrevCorr yes; solver smoothSolver; smoother symGaussSeidel; nSweeps 1; tolerance 1e10; relTol 0; minIter 1; } "pcorr.*" { solver PCG; preconditioner { preconditioner GAMG; tolerance 1e05; relTol 0; smoother DICGaussSeidel; nPreSweeps 0; nPostSweeps 2; nBottomSweeps 2; cacheAgglomeration false; nCellsInCoarsestLevel 10; agglomerator faceAreaPair; mergeLevels 1; } tolerance 1e10; relTol 0; maxIter 100; }; p_rgh { solver GAMG; tolerance 1e08; relTol 0.01; smoother DIC; nPreSweeps 0; nPostSweeps 2; nFinestSweeps 2; cacheAgglomeration true; nCellsInCoarsestLevel 10; agglomerator faceAreaPair; mergeLevels 1; } p_rghFinal { solver PCG; preconditioner { preconditioner GAMG; tolerance 2e09; relTol 0; nVcycles 2; smoother DICGaussSeidel; nPreSweeps 2; nPostSweeps 2; nFinestSweeps 2; cacheAgglomeration true; nCellsInCoarsestLevel 10; agglomerator faceAreaPair; mergeLevels 1; } tolerance 2e09; relTol 0; maxIter 20; } "(Ukomega).*" { solver smoothSolver; smoother symGaussSeidel; nSweeps 1; tolerance 1e8; relTol 0; minIter 1; } "cellDisplacement.*" { solver smoothSolver; smoother symGaussSeidel; nSweeps 1; tolerance 1e8; relTol 0; minIter 1; } } PIMPLE { momentumPredictor yes; nOuterCorrectors 1; nCorrectors 3; nNonOrthogonalCorrectors 0; correctPhi yes; moveMeshOuterCorrectors yes; turbOnFinalIterOnly yes; } relaxationFactors { fields { } equations { ".*" 1; } } cache { grad(U); } // ************************************************** *********************** // I hope it is helpful. 

July 9, 2014, 10:56 

#265 
New Member
Ali
Join Date: Oct 2013
Posts: 25
Rep Power: 3 
Dear Jianxi Yao,
Thank you so much. I will run the simulation using your settings. Do you have any suggestion about meshing? I have generated mesh using pointwise (with boundary layer) and snappyHexMesh (without boundary). I have found that Prof. E Patterson's mesh was generated using pointwise. Thank you again for your kind help, Ali 

August 12, 2014, 09:55 
CFD problems KCS

#266 
New Member
David Fuentes
Join Date: May 2014
Posts: 4
Rep Power: 3 
hi partners
I'm trying to make a CFD analysis of the KCS hull using interFoam, but I can't find the convergence and when I see the results on paraFoam I can see some interference or something, can you help me? 

August 13, 2014, 05:46 
waves2Foam

#267 
Member
carlos
Join Date: Apr 2011
Posts: 37
Rep Power: 6 
Dear All,
I have simulated a fast planing boat some time ago, and as I remember, the problem with interFoam (or interDyMFoam if you use dofs for the hull) was the shock of the sudden speed acting on the hull and the waves generated reflecting on the sides and end of the domain.
Regards, Carlos. 

August 13, 2014, 07:27 
adding dumping on a dof

#268  
New Member
Kumar
Join Date: Aug 2014
Posts: 4
Rep Power: 2 
Hi Carlos
I am new to OpenFoam and I am trying to simulate free surface flow around ship hull with trim and sinkage. I have been able to compile waveDyMFoam and it works well for a small floating block in 2d as given in the video below, https://www.youtube.com/watch?featur...&v=YKbj_7JMRl8 But when I try to simulate ship motions, it doesn't converge. It diverges in a few time steps. Please help to find the cause. How to add dumping on a dof? Could you please give a reference. Regards, KM Quote:


August 13, 2014, 10:17 

#269 
Member
carlos
Join Date: Apr 2011
Posts: 37
Rep Power: 6 
Hi KM,
Is a long time I am not working on this, but I attach the pointDisplacement file I was using. My believe is that damping has no influence on the steady state but it helps to rich it. Keep in mind that I was not imposing any waves nor studing the motion. I just wanted to get the trim and sinkage. Therefore, springs will affect the result but not dumping. If you are using waves or studding the motion, this approach would not be correct. Hoppe it helps. Good luck and good results. Regards, Carlos. 

August 13, 2014, 10:26 

#270 
Member
carlos
Join Date: Apr 2011
Posts: 37
Rep Power: 6 
Hi KM,
Is a long time I am not working on this, but I attach the pointDisplacement file I was using. My believe is that damping has no influence on the steady state but it helps to rich it. Keep in mind that I was not imposing any waves nor studding the motion. I just wanted to get the trim and sinkage. Therefore, springs will affect the result but not dumping. If you are using waves or studding the motion, this approach would not be correct. Hoppe it helps. Good luck and good results. Regards, Carlos. PD: Added waveProperties 

August 14, 2014, 05:06 

#271 
New Member
Kumar
Join Date: Aug 2014
Posts: 4
Rep Power: 2 
Hi Carlos
Thank you for your response. I tried adding the two files in my simulation. But the solution still diverges. I have uploaded the files here http://www.mediafire.com/download/cs...1qv/wigley.zip . If you can help. With warm regards, KM 

August 15, 2014, 15:09 

#272 
Member
carlos
Join Date: Apr 2011
Posts: 37
Rep Power: 6 
Hi KM,
I am sorry not to be of more help. Keep on trying, finally you will get there. Best regards and good inspiration, Carlos. 

August 26, 2014, 00:30 

#273 
New Member
Kumar
Join Date: Aug 2014
Posts: 4
Rep Power: 2 
Hi Carlos
Thanks for the reply and your comments. I was our of town so couldn't read it earlier. Could you please help me to understand the RelaxationZone startX and endX definition. In my case flow is along x axis. Relaxationzone is starting from x = 40 and ends at x = 80. When we write, startX (40 40 0) and endX (80 40 0) what does it defines? Are they the opposite corners of the rectangle? I am still trying out simulations based on your comments. If someone else can also help me please. Thanks KM 

August 26, 2014, 04:27 

#274 
Member
carlos
Join Date: Apr 2011
Posts: 37
Rep Power: 6 
Hi Kumar,
As you say, the coordinates are the points of a rectangular section volume where the relaxation is applied. (minX minY minZ) (maxX maxY maxZ) After my previous reply, I noticed some omissions from my side:
Regards, Carlos. 

August 27, 2014, 05:13 

#275 
New Member
Kumar
Join Date: Aug 2014
Posts: 4
Rep Power: 2 
Hi Carlos
Thanks a lot for the response again. I am now trying out first with a rectangular block instead of a ship shape. I have included your comments. I have a question. What is Tsoft in the waveProperties dict file? When I keep it 0, the simulation seems to diverge. When I keep it 2, which I noticed in the some example file, I observe the water surface is no longer flat, there is a pulse shape formation near the inlet. Regards, KM 

August 28, 2014, 07:04 

#276 
Member
carlos
Join Date: Apr 2011
Posts: 37
Rep Power: 6 
Hi Kumar,
I remember to have that issue with the Tsoft. Unfortunately I do not recall why, but you will better ask in the waves2Foam forum. I beleave it is a delay in the start of the wave, so when you use only current it can be 0, but if you apply waves is better to use something like 2 to avoid the first impact. It is not clear to me in the example of the W2F file: " // Ramp time of 2 s // Foam::sin(2 * mathematicalConstant:i / (4.0 * Tsoft_) * Foam::min(Tsoft_, runTime.time().value() )) // and explicitly "1" for Tsoft = 0 Tsoft 2; " from:http://openfoamwiki.net/index.php/Contrib/waves2Foam Regards, Carlos. 

August 28, 2014, 11:23 

#277 
New Member
saman
Join Date: Apr 2012
Posts: 4
Rep Power: 5 
Hi all OpenFOAM users,
I am working on resistance calcualation of Wigley hull, very very repeated subject! I read all the posts here but I still have problem in forces results which are not suitable even for the OF222 Wigley tutorials without any changes, without motion !!! results for wave elevation have good agreement with experimental results but for forces are completely wrong for different Froude numbers!!! I try to use fvschemes and fvsolutions which Jianxiyao mentioned above but these files dosent work in OF222 and it also seems for moving case! If anyone have a suitable example or could help me to solve my problem I will be appreciate. If you need my files to check I will send it. Regards, Saman 

September 1, 2014, 00:47 

#278 
Member
Sachin
Join Date: Aug 2014
Location: India
Posts: 45
Rep Power: 2 
Hi all,
I have run a drag force analysis of accustom hull using LTSInterFoam. But after 12000 runs the free surface is seen above the ship hull. What could be the possible reason. Could it be because the solution is not yet stable. Should I run this for more number of iterations? One more thing, I need to find the drag force on the hull. The function to write the force that I have asks for only one density value. How can that function give me the drag when it is a multiphase problem. There should be two values of density changing with the value of alpha1. Can anybody help me with this? Below I am attaching few results: 1) The meshed hull with value of alpha1 shown. Blue region is air; red region is water. 2) Free surface after 100 iterations 3) free surface after 12000 iterations. inlet is at left and outlet at the right 

September 2, 2014, 13:45 
Nearwall treatment for a komega SST model

#279 
New Member
Join Date: Oct 2013
Posts: 6
Rep Power: 3 
Hi,
I would like to check that I am working under the right assumptions regarding the near wall treatment of my komega SST model. I have applied the nutkRoughWallFunction to my hull patch so I expect the wall function to be used and I should not need to capture the laminar sublayer but instead can target the log law region with 30<y+<300? Did I get it all wrong? Also is the wall function “scalable”? Since my layer thicknesses are constant along the length of the model I am wondering what would happen if in one area of the model the first cell was contained within the laminar sublayer. Would the wall function recognise the transition to the composite region? Thanks for your help! Last edited by jule; September 3, 2014 at 13:57. 

October 16, 2014, 02:15 

#280  
Senior Member
Fatema Zandi Goharrizi
Join Date: Mar 2009
Posts: 131
Rep Power: 8 
Quote:
OpenFOAM can do mesh adaption (tracking the moving surface) with dynamic mesh solvers such as interDyMFoam. in dynamicMeshDict the parameters would be difined and it is one of the capability of dynamic mesh of OpenFOAM. but as i know it just works for hexahedral meshes. regards Zandi 

Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
FreeSurface Ship Flow  Boundary Conditions  James Date  CFX  1  February 19, 2013 06:42 
ship freesurface analysis  Andrea Mercuri  CDadapco  0  September 28, 2004 11:01 
Free Surface Flow for Ship  sam  FLUENT  6  October 24, 2003 05:29 
viscous free surface flow past a ship hull  lololo  Main CFD Forum  0  June 12, 2002 23:02 
meshing for surface ship flow  boris  FLUENT  0  April 24, 2002 20:27 