[GauthierL]

Hi,

I'm trying to manage to simulate a falling object (solid) in a homogeneous liquid (like water and later LBe). To manage this kind of simulation, I need several solvers :

"- a fluid flow solver with support for moving meshes;
- force calculation on the boundary;
- a 6-DOF solver that can calculate the position/motion based on the forces and intertial parameters. This will determine the boundary motion for you;
- an automatic mesh motion solver, which will deform the mesh based on prescribed boundary motion."
(Citation from Hrvoje Jasak)

I had a look during the 2 last months on this forum to try to figure out how to do. I'm not a pro OpenFOAM and my time is running out.
What I have done :

1. Use a dynamic mesh (floatingObject). The problem is, when the object moved a lot, the mesh crash because the cell volume is too low and Co number too high.
   I wanted to use
   

   dynamicFvMesh   dynamicRefineFvMesh;

   instead of :
   

   dynamicFvMesh   dynamicFvMesh;

   The problem is, we don't change the topology of the mesh. Therefore, the mesh will crash when the object move a lot or rotate.
2. Hence, I started to have a look on the TopoChanger. But, this is a way harder! If I'm not mistaking, no tutorial exist in of2.3. We need to install extension and implement the new library made by Sandeep Menon and his team.
   Nevertheless, it's not trivial and I'm stuck.
   
   So I tried to use this :
   

   dynamicFvMesh       movingConeTopoFvMesh;
   
   movingConeTopoFvMeshCoeffs 
   { 
       motionVelAmplitude      (0.00051 0 0); 
       motionVelPeriod         10; 
       leftEdge                0; 
       leftObstacleEdge        0.01; 
       rightObstacleEdge       0.02;
   
       right 
       { 
           minThickness        1e-8; 
           maxThickness        6e-3; 
       } 
       left 
       { 
           minThickness        1e-4; 
           maxThickness        6e-4; 
       } 
   }

   Unfortunately, I have an error message as follow :
   

   --> FOAM FATAL ERROR: 
   Face extrusion zone contains no faces. Please check your mesh definition.
   
       From function void Foam::layerAdditionRemoval::checkDefinition()
       in file layerAdditionRemoval/layerAdditionRemoval.C at line 86.
   
   FOAM aborting
   
   #0  Foam::error::printStack(Foam::Ostream&) at ??:?
   #1  Foam::error::abort() at ??:?
   #2  Foam::layerAdditionRemoval::checkDefinition() at ??:?
   #3  Foam::layerAdditionRemoval::layerAdditionRemoval(Foam::word const&, int, Foam::polyTopoChanger const&, Foam::word const&, double, double, Foam::Switch) at ??:?
   #4  Foam::movingConeTopoFvMesh::addZonesAndModifiers() at ??:?
   #5  Foam::movingConeTopoFvMesh::movingConeTopoFvMesh(Foam::IOobject const&) at ??:?
   #6  Foam::dynamicFvMesh::addIOobjectConstructorToTable<Foam::movingConeTopoFvMesh>::New(Foam::IOobject const&) at ??:?
   #7  Foam::dynamicFvMesh::New(Foam::IOobject const&) at ??:?
   #8  
    at ??:?
   #9  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
   #10  
    at ??:?
   Aborted (core dumped)

3. 
   I'm trying as well to use IBM method, but this is less accurate and moreover the mesh must be very accurate every places the object will be. It's not the best but if someone knows an IBM which refine, I might be really interested in.

So in the 2 first cases, I'm stuck and I can't go ahead. My level in OF do not allow me to change solvers. I'm wondering if anyone has done this kind of job before and can help me?

Do you think it's possible to manage that?

I highly thanks you for your help,

Sincerely yours,

Gauthier

[Kuifeng]

Hi GauthierL,

Did it work at last? I am interested to see how the falling object is to be simulated.

[kennyadapter]

Hi GauthierL,
I just started learning openfoam.I am doing the simulation of falling objects. Have you solved your problem?
thanks.