CFD load importing and mapping on a structural model

I want to perform static analysis in MSC PATRAN using loads obtained from CFD done in ANSYS-FLUENT. I want to know:

1) Does PATRAN supports direct import of loads externally (in my case from ANSYS-FLUENT)? If yes how to do it efficiently?

2) How to map loads on structural model to get best results.

3) If there is a better way to perform this analysis please do suggest.

Thanks in advance

Regards

Ahmad Altaf

0 Arthur Hickson over 5 years ago

Hi,

1)Patran can import result files in various formats. The results can be displayed on a mesh that corresponds to the analysis model . The resulting vector or fringe plot can be used to create a Spatial FEM Field. The field can be used to apply LBCS, e.g pressure, to another mesh in the Patran db.

2)Most exact is to use same mesh as CFD - one to one node mapping. But probably impractical. Mapping loads generally means that you are changing the mesh distribution. However you "map" the load the change in mesh requires that you "distribute" or spread the load over an area and this process "dilutes" the original spatial resolution. The change in element normal directions due to different element sizes between the original and new mesh mean that element pressures will give rise to different resolved nodal forces. For "accurate" mapping the overall process should take into account the original "OLOAD" and ensure that the mapped "OLOAD" is the same, otherwise you have changed the total load (forces and moments) on the structure. This is non-trivial to achieve.

3)Start simply, try using pressure mapping and ensuring that the second mesh has sufficient elements to capture the pressure variations of the first. Then the OLOAD differences will hopefully not be significant.

To start have a look at this article:

https://simcompanion.mscsoftware.com/infocenter/index?page=content&id=KB8016606

This is a topic that aerospace companies have spent years working up their own internal methodologies and processes around the tools and limitations of software and computers. You can read up on the "SPLINEx" options in the Nastran manual developed for aeroelastic mapping and the Spline6/7 methods introduced in version 2005 for coupling aerodynamic and structural models.

best regards

Arthur
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