Mapping forces defined at coarse mesh to fine structural mesh
Mapping forces defined at coarse mesh to fine structural mesh
(OP)
Hi,
I am trying to setup an analysis where the velocities have been recorded in a fluid medium at particular locations. Now I have to use Morison equation to calculate the force at those particular locations.
The structure under analysis is to be applied with forces generated by the Morison equation. As mentioned earlier these records are available at few locations or in other words these forces are available over a coarse mesh. The flexible structure is discretized using a much finer mesh. When the structure vibrates the forces have to be mapped appropriately to the structure's node location at the current time step.
Is there a feature in ANSYS which can help me achieve this. I know there are mesh mapping algorithm when present in ANSYS when a Fluid Structure Interaction problem is solved. But in my case the fluid side has already been replaced with velocity or forces.
I appreciate you help.
HN
I am trying to setup an analysis where the velocities have been recorded in a fluid medium at particular locations. Now I have to use Morison equation to calculate the force at those particular locations.
The structure under analysis is to be applied with forces generated by the Morison equation. As mentioned earlier these records are available at few locations or in other words these forces are available over a coarse mesh. The flexible structure is discretized using a much finer mesh. When the structure vibrates the forces have to be mapped appropriately to the structure's node location at the current time step.
Is there a feature in ANSYS which can help me achieve this. I know there are mesh mapping algorithm when present in ANSYS when a Fluid Structure Interaction problem is solved. But in my case the fluid side has already been replaced with velocity or forces.
I appreciate you help.
HN





RE: Mapping forces defined at coarse mesh to fine structural mesh
Force Calculation:
The place I am getting stuck now is calculation of force using Morison equation (http://en.wikipedia.org/wiki/Morison_equation). This equation depends on the relative velocity between fluid and structure. So in my analysis I have to first calculate the structural velocity at keypoints and then use Morison's formula to get the force at keypoints. I will appreciate if anyone can comment if I am thinking in the right direction.
HN
RE: Mapping forces defined at coarse mesh to fine structural mesh
//signed//
Christopher K. Hubley
Mechanical Engineer
Sunpower Incorporated
Athens, Ohio
RE: Mapping forces defined at coarse mesh to fine structural mesh
In my case I have not started the analysis yet. I have fluid velocity records at some locations (may not coincide with any node on the structure). Now I want to calculate force using Morison equation (http://tiny.cc/l6zxi) that uses relative velocity between fluid and structural velocity.
My first question is:
How do I define such kind of non-linear forcing function (http://tiny.cc/l6zxi)?
My second question is:
Does CBDOF will map my input velocities at some arbitrary locations to node locations?
I apologize if I was not clear before.
HN
RE: Mapping forces defined at coarse mesh to fine structural mesh
The CBDOF command merely maps displacement results onto the cut boundaries of your submodel. Other boundary conditions (temperatures, velocities, etc.) will have to be carefully applied to both models in an identical fashion (if they are, in fact, important in the sub-model).
I don't have experience with the Morrison equation, but it looks like you're doing a harmonic response analysis first, and then mapping the results onto a smaller submodel (in an area of interest), is that correct? It's hard for me to make suggestions about how to apply the actual loads without seeing a picture or two.
I believe that you'll want to solve your larger dynamic model, and then map the cut-boundary displacement results at the phase angle you're interested in onto the (static?) submodel.
If temperatures are important, you'll also want to interpolate your thermal results onto the submodel with the BFINT command and perform a steady-state conduction run before running solving the structural submodel.
//signed//
Christopher K. Hubley
Mechanical Engineer
Sunpower Incorporated
Athens, Ohio