Following is another great article from the Siemens PLM GTAC team.
NX Flow solver in Advanced Simulation requires all elements used in modeling Flow to be 3D elements. While the solid mesh for a design part occupies the part itself, the fluid mesh occupies the void between the bodies. Because the void itself is not a body, one must create a solid body to occupy the void. This solid body is generated in the idealized part I and then a mesh is applied on this body with 3D fluid elements using the NX meshing tools. This internal fluid volume can be created by one of the following 3 methods:
In this article we will go over the 3rd method specified above to extract the flow volume. Consider the task of extracting the internal flow volume in the following valve:
Here are the steps to extract the internal volume:
Thanks to SR for the tip.
Flow volumes in the context of an assembly can be created using surface wrapping techniques in Advanced Simulation. NX 9 CFD Modeling is a new pre-processing add-on product for CFD analyses. The attached video demonstrates the surface wrapping capabilities in the context of an exhaust manifold assembly. The manifold, exhaust pipe, gasket, and cylinder head geometry is represented.
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I am using NX 8.5. Is there any way in NX 8.5 to get the flow volumes in the context of an assembly?
I would appreciate your help.
You can try to unite all bodies in the assembly to form a single solid body. Then use synchronous modeling's Delete Face command as documented in the original topic of this thread.
Thank you for your answer.
I tried your method. It went well, till at the end which gave me this error:
Delete failed because the remaining faces cannot close the area after deleting the slected face.
Any idea what is this error for?
Delete Face begins with a solid body and must finish with a solid body. It literally deletes the faces you select and tries to close the holes that remain. Typically when you get this message it is because NX was unable to close a hole. Take a block with a cylindrical hole passing through it as an example. If you choose to delete the hole, then the solid is left with free edges at each end of the cylinder. For each free edge loop, NX will create a face to "heal" the solid body. If every free edge loop produces a face, then you should end up with a solid body.
It sounds like one or more of the free edge loops on your solid body failed to produce a face. You can diagnose the error by choosing to not heal the solid body in the Delete Face dialog. In Delete Face, expand the Settings block of the dialog and turn OFF Heal. The output from Delete Face will be a sheet body with many free edges. Examine your free edge loops to see if any look like they would have a difficult time creating a face. You could even try creating faces from the loops with N Sided Surface, Bounded Plane, or Fill Surface commands.
It could be that you selected too many faces for the delete face operation. That is, if you selected a face that should remain as part of the fluid volume, then I could see this error popping up. That's about all I can think of without having the part to test with.
The error during the unite that the tool is outside of the body means that NX thinks there is no intersection between the bodies to act as the "conduit" to unite the two into a single body. Without having your geometry, I can't really elaborate more on ways to achieve the fluid body that you desire. I have no idea what size your geometry is, but it seems like a 0.05mm gap can be idealized away to a 0.00mm gap. I imagine that a good mesh that represents that small of a gap is going to produce a ton of elements with little benefit with respect to the analysis results. Just for reference, default NX Modeling tolerance is 0.01mm. Typical minimum element sizes are a minimum of 10-100 times larger than the modeling tolerance.