CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   CD-adapco (http://www.cfd-online.com/Forums/cd-adapco/)
-   -   Star CCM Overset Mesh Error (Rotating Turbine) (http://www.cfd-online.com/Forums/cd-adapco/114253-star-ccm-overset-mesh-error-rotating-turbine.html)

thezack March 7, 2013 13:42

Star CCM Overset Mesh Error (Rotating Turbine)
 
Hi, I am having an error in my simulations that I cannot seem to fix. I have a turbine (DFBI 1 axis rotation) rotating inside of another larger mesh. The purpose of the simulation is to simulate a gravitational vortex turbine (water enters from the top of a funnel and swirls down the funnel creating a vortex, and a turbine is placed at the bottom to rotate a shaft). The simulation is 3D. Mesh 1 is the polyhedral mesh of the funnel volume, and mesh 2 is the overset mesh of the turbine completely enclosed within mesh 1. Both are polyhedral mesh, mesh 2 has prism layer mesher, surface remesher, and surface wrapping meshing models. Mesh 1 has polyhedral, prism layer, and surface remesher.

I keep trying varying levels of mesh size for mesh 1 and mesh 2, and I keep getting this error message:


Updating indirect region interface Overset Mesh 1 between Turbine and SwirlyMarch5NoDamEntrance.
Failed to cut hole in region SwirlyMarch5NoDamEntrance.
This might be due to an overlapping of overset regions or due to invalid mesh configuration!


Am I using the wrong meshing models? Should mesh 1 or mesh 2 be finer? Should they be roughly the same mesh size or should 2 be much finer? I am new to this, and I have no idea how to proceed. I keep messing around with the mesh properties and nothing seems to work. I am not sure if there is something specific I should be changing. The documentation on Star CCM+ has a troubleshooting section, but it does not say how to fix those kinds of errors. Ive tried setting up the scalar overset mesh type scene, but of course it is in 2-D when my simulation is 3-D, so I cannot see where on the mesh the error is. I am pretty stumped here and would greatly appreciate any help. Thanks!

ryancoe May 14, 2013 15:08

Zack,

The overset mesh can be challenging to configure. I've had some luck using a series of plane sections with the Overset Scalars to try to find the locations where you're having problems. Its a bit unwieldy, but its the best thing I've found thus far.

If that doesn't help, I would try to simplify the geometry to make it more overset-friendly until you get it working, and then work back to full fidelity.

hyderkhan74 September 27, 2013 07:58

Hi
I have the same problem so i wonder how you solve it ?
thanks in advance

ayannath23 December 11, 2013 04:09

Hi Zack,
I think the error is due to improper mesh..
Please go through the tutorial in star ccm+ help (Tutorial Guide > Motion > DFBI: Lifeboat with Overset Mesh). It explains nicely about the meshing requirements.

Thanks,
Ayan

Kush7876 April 26, 2016 02:03

Problem Solved
 
Proper meshing would solve this problem, you should make sure that there should at least 3 cells of overset mesh are there on 1 cell of background mesh and also you should maintain the same through out the path in which overset mesh is travelling.

Further please refer to "best practices for overset mesh" in star user guide


All times are GMT -4. The time now is 21:16.