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May 18, 2015, 21:17 |
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#101 |
New Member
Pablo Murillo
Join Date: Apr 2015
Location: Cádiz, Spain
Posts: 3
Rep Power: 11 |
Hi all of you!
First of all, many thanks for your help. This treath is incredible. I am studing this problem too and finally I have been able to lauched it correctly on OpenFOAM 2.3.x thanks to this treath. jerikanti, you can find attached it. I hope you find it interesting Best Regards, Pablo Case: https://goo.gl/ygHRKD PD: Mesh is not the suitable one but it is enough |
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May 23, 2015, 07:38 |
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#102 |
New Member
Amin S
Join Date: Mar 2014
Posts: 5
Rep Power: 12 |
Dear All,
I've started working on VIV of a cylinder lately.thanks to Maimuna and Bruno,I could perform two cases using OF2.3.0: first case a forced oscillation with a vertical displacement excitation of cylinder in Re=3900. second a two degree of freedom vibration of cylinder subjected to steady current at Re=200,based on scenario1 with a minor modification in blockMeshDict file and using coefficients like K(stiffness),c(damping),.. from experimental data. questions: 1.what constants should be used for springs&dampers? should we derive it from a beam model analogy of a cylinder span under fluid forces? 2.why in scenario1,4 springs&dampers used for 2 degree of freedom motion?(maybe springs are considered to act in one direction,i.e. only positive displacement) we could restrain the cylinder with 2 set of spring&damper in each direction.. 3.has anyone performed VIV analysis for a coupled system of fluid-structure,including FSI in OpenFoam? like implementation of icoFsiElasticNonLinULSolidFoam solver in FoamExtend..for example HronTurekFsi tutorial case.. |
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June 15, 2015, 05:16 |
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#103 |
Member
Thaw Tar
Join Date: Apr 2013
Location: Yangon, Myanmar
Posts: 35
Rep Power: 13 |
Dear Amin S,
I read your dynamicDict file but still have not run yet. Could you run that case? How is the motion amplitude of the cylinder? I think your mass ratio is about 1/100 which is extremely small and will cause very large amplitudes. Can your mesh handle this amplitude? As for me, I faced a lot of simulation blow ups because the mesh distorts too much because of very large cylinder amplitudes and the solution diverged. By the way, I could run some cases with 2DoF movement using only a spring with length 0. These just worked fine. Regards Thaw Tar P.S. In my research, I calculated spring constants using beam analogy and I think these are fine. (Actually, I could not find a better approach) |
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August 9, 2015, 11:09 |
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#104 |
New Member
Pablo Murillo
Join Date: Apr 2015
Location: Cádiz, Spain
Posts: 3
Rep Power: 11 |
Hi all,
Anybody knows where can I find simulation or experimental data to validate a case of 2D spring mounted laminar cylinder with 1DOF, and 2DOF too? For example, Cl(t) and Cd(t) for low Re, around 200. Thanks you in advance. Best regards, Pablo |
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September 17, 2015, 10:15 |
restraints problems
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#105 |
New Member
Agnese Paci
Join Date: May 2015
Location: Bologna, Italy
Posts: 14
Rep Power: 11 |
Dear all,
I'm trying to simulate a floating vertical cylinder with mooring systems. I thought to use verticalSprings implented in dynamicMeshDict/restraints, but it does not work. I put anchor points on the bottom boundary and refAttachmentsPt on the bottom of my cylinder. Could it be correct? Can anyone help me using these restraints? thank you very much Agnese |
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October 12, 2015, 17:01 |
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#106 |
Member
Davi Barreira
Join Date: Apr 2014
Location: Fortaleza
Posts: 76
Rep Power: 12 |
Agnese, post your dynamicMeshDict, so we can help you out.
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October 13, 2015, 03:53 |
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#107 |
New Member
Agnese Paci
Join Date: May 2015
Location: Bologna, Italy
Posts: 14
Rep Power: 11 |
Hi david,
you are very very kind! Fortunately, at the end, I could! My model runs !!! Thank you very much anyway! have a good day Agnese |
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October 13, 2015, 21:05 |
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#108 |
Member
Davi Barreira
Join Date: Apr 2014
Location: Fortaleza
Posts: 76
Rep Power: 12 |
Edited: No problem. I had some questions too, but I read the code and now I think I understood how the linearSpring is implemented.
Last edited by davibarreira; October 14, 2015 at 20:30. |
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December 1, 2015, 02:33 |
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#109 | |
New Member
Jason
Join Date: Dec 2015
Posts: 12
Rep Power: 10 |
Quote:
I'm a beginner and also trying to simulate the vortex induced vibration. Could you share your case files with us as I found you have done a lot of work on it and it would be useful for a lot of learners like myself? Thank you! Jason Last edited by llib11ik; December 1, 2015 at 03:56. |
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December 1, 2015, 03:47 |
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#110 | |
New Member
Jason
Join Date: Dec 2015
Posts: 12
Rep Power: 10 |
Quote:
Thanks for your sharing! I download your file and follow your instructions, but I still can not run it (under OF240). Can you please help? Thank you very much! Jason Errors are: Code:
ceeyang@ceeyang-HP-EliteDesk-800-G1-SFF:~/OpenFOAM/ceeyang-2.4.0/run/tutorials/incompressible/pimpleDyMFoam/oscillatingCylinder$ ./Allclean Cleaning /home/ceeyang/OpenFOAM/ceeyang-2.4.0/run/tutorials/incompressible/pimpleDyMFoam/oscillatingCylinder case ceeyang@ceeyang-HP-EliteDesk-800-G1-SFF:~/OpenFOAM/ceeyang-2.4.0/run/tutorials/incompressible/pimpleDyMFoam/oscillatingCylinder$ ./Allprepare ./Allprepare: line 1: #!/bin/sh: No such file or directory ./Allprepare: line 3: gmsh: command not found /*---------------------------------------------------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.4.0 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ Build : 2.4.0-f0842aea0e77 Exec : gmshToFoam channel-with-cylinder.msh Date : Dec 01 2015 Time : 16:11:20 Host : "ceeyang-HP-EliteDesk-800-G1-SFF" PID : 9491 Case : /home/ceeyang/OpenFOAM/ceeyang-2.4.0/run/tutorials/incompressible/pimpleDyMFoam/oscillatingCylinder nProcs : 1 sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). fileModificationChecking : Monitoring run-time modified files using timeStampMaster allowSystemOperations : Allowing user-supplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time #0 Foam::error::printStack(Foam::Ostream&) at ??:? #1 Foam::sigSegv::sigHandler(int) at ??:? #2 ? in "/lib/x86_64-linux-gnu/libc.so.6" #3 Foam::PtrList<Foam::polyPatch>::operator[](int) const at ??:? #4 ? at ??:? #5 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #6 ? at ??:? ./Allprepare: line 4: 9491 Segmentation fault (core dumped) gmshToFoam channel-with-cylinder.msh /*---------------------------------------------------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.4.0 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ Build : 2.4.0-f0842aea0e77 Exec : changeDictionary Date : Dec 01 2015 Time : 16:11:21 Host : "ceeyang-HP-EliteDesk-800-G1-SFF" PID : 9517 Case : /home/ceeyang/OpenFOAM/ceeyang-2.4.0/run/tutorials/incompressible/pimpleDyMFoam/oscillatingCylinder nProcs : 1 sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). fileModificationChecking : Monitoring run-time modified files using timeStampMaster allowSystemOperations : Allowing user-supplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 0 --> FOAM FATAL ERROR: Cannot find file "points" in directory "polyMesh" in times 0 down to constant From function Time::findInstance(const fileName&, const word&, const IOobject::readOption, const word&) in file db/Time/findInstance.C at line 203. FOAM exiting |
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December 1, 2015, 05:24 |
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#111 |
Senior Member
ok
Join Date: Oct 2013
Posts: 346
Rep Power: 13 |
Code:
hi Maimouna, Thanks for your sharing! I download your file and follow your instructions, but I still can not run it (under OF240). Can you please help? Thank you very much! Jason could you please post your case to have a look, or you could contact me via HTML Code:
may78may@hotmail.com |
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December 1, 2015, 06:31 |
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#112 |
New Member
Jason
Join Date: Dec 2015
Posts: 12
Rep Power: 10 |
Dear Maimouna,
Thanks for the kind reply! Please see my case file as attached. My plan for the work is as below, which is quite similar as yours: 1) model the flow around a static cylinder (done, as attached); 2) model the flow around a forced vibrating cylinder (try to modify my current case by learning from your case); 3) model the flow around a freely vibrating cylinder (final task). Currently I'm still at the stage 2) and I'm new to OF, so I have a lot to learn. Could you please give me some advice? At the same time, I'm also studying the cases you uploaded and trying to figure out how to make the cylinder vibrate. Thank you very much! Jason |
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December 1, 2015, 08:10 |
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#113 |
Senior Member
ok
Join Date: Oct 2013
Posts: 346
Rep Power: 13 |
Dear Jason,
could you please provide me all information about your case laminar or turbulence? Reynolds number? case domain and boundaries? OpenFOAM version? operating system and its version? all other information to be able to give you feedback. Regards Maimouna |
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December 2, 2015, 08:07 |
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#114 | |
New Member
Jason
Join Date: Dec 2015
Posts: 12
Rep Power: 10 |
Dear Maimouna,
After I installed gmsh, I can successfully run your case "oscillatingCylinder" now. Thanks! I also made some modifications to my previous case to make the cylinder vibrate now (forced vibration). The information of my case: Turbulent Re=9500 2D channel with velocity inlet, pressure outlet, nonslip walls and a moving cylinder OpenFOAM 2.4.0 UBUNTU 14.04.3 LTS My case files are also attached for more detailed info. Next I'd like to make the cylinder vibrate freely (vortex induced vibration). Could you please kindly give me some advice on how to modify my current case to model the VIV? Thank you very much! Jason Quote:
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December 3, 2015, 00:18 |
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#115 | |
New Member
Jason
Join Date: Dec 2015
Posts: 12
Rep Power: 10 |
Dear Thaw Tar,
I followed Maimouna's instructions but only got many XY files in the "logs" directory. Could you kindly let me know how you create the single center of mass file? Thank you very much! Jason Quote:
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December 3, 2015, 05:01 |
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#116 | |
Senior Member
ok
Join Date: Oct 2013
Posts: 346
Rep Power: 13 |
Quote:
I'm bit busy theses days, I'll back to your cases as soon as I can. All the best Maimouna |
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December 6, 2015, 23:03 |
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#117 |
New Member
Jason
Join Date: Dec 2015
Posts: 12
Rep Power: 10 |
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December 9, 2015, 11:20 |
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#118 |
Senior Member
ok
Join Date: Oct 2013
Posts: 346
Rep Power: 13 |
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December 11, 2015, 03:32 |
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#119 | |
New Member
Jason
Join Date: Dec 2015
Posts: 12
Rep Power: 10 |
Dear Maimouna,
First of all, thank you very much for your kind help. With your help and learning from the posted cases, currently I can run a case with free vibrating cylinder. However, still a few questions: 1. Follow your method below, I can only get the x of the mass center. Do you know how to get all x y z? 2. For the attached case, I can find the cylinder is moving, but velocity and displacement are very small (the order is e-6 to e-9). I tried to change the mass, stiffness and damping but none of them works. Can you give me suggestions to make the cylinder move more obviously? Thank you! Best regards Jason Quote:
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December 11, 2015, 04:25 |
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#120 |
Senior Member
ok
Join Date: Oct 2013
Posts: 346
Rep Power: 13 |
Dear Jason,
I'm away from my Ubuntu machine now. Give me some days then I'll back to you. All the best. Maimouna |
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