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Pedro ROS August 26, 2007 07:59

scroll compressor: NOT REMESHING 2ND LAYER
Hello, I am working on a scroll compressor,2D simplest models as possible (I got 2models 1meshed in TRI the other one QUAD cells, STRUCTURED,PAVE, size function Proximity:cells per gap:2,grow rate:1.2,max:2mm; from walls. SMOOTH LAYERING A REMESH activated; Parameters, alike to those in the In_Cylinder tutorial, sizes equals to original ones in the compressor mesh.

The problem seems to be caused by the first layer of the mesh in contact with the moving spiral wall, which is modified, but for any unknown reason it is not splited nor collapsed to the second row of cells (both values alpha=0.5 ), so when the wall touches the second layer, the first one generates negative volumes, stopping the Mesh Motion Preview after 120 iterations (time step iteration 120e-05 seconds).


_ Do you know why this is happening or how can I solve it?

_ Do I need a UDF to control the mesh? If so, wich one?

Any advice is really welcome, After a week working on it (and on the Fluent User's Guide) with no results I am pretty lost.

Thanks in advance to any of you.


Pedro ROS

Pedro ROS August 31, 2007 08:23

Re: scroll compressor: NOT REMESHING 2ND LAYER
Hello, By studying deeper the Users Guide, I noticed:

"If you want to use dynamic layering on cells adjacent to a moving wall that do not span from boundary to boundary, you must separate those cells which are involved in the dynamic layering and use the sliding interfaces capability in FLUENT to transition from the deforming cells to the adjacent non-deforming cells (see Figure 10.6.6). For a moving interior face, the zones must be separated such that they are either expanding or collapsing on the same side. No one zone can consist of both expanding and collapsing layers."

So I guess Layering will not work due to the spiral, which reduces the cell size before the (moving) contact point in between spirals and increases it after it. I thought about using only spring Smoothing with the minimum number of layers possible, to avoid a row interfere in the next... Did anybody tried to solve a scroll compressor like this? Any clue?



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