[maheshchamarti]

Hi,
I am doing a steady state analysis of a radial turbo expander. I have created the meshes using turbogrid. There is a very minute radial gap between the two meshes. I am using the mixing plane mode for stage interface. I would like to know if this will affect my solution. Thank you.

[AtoHM]

I'd rather rework my meshes to fit together instead of taking the risk of getting non-valid results, though CFX is able to handle small deviations.

If you set up your flow path correctly and consistently for both sides before meshing you'll get matching faces. But take the time and fix stuff like that right away. Later you might want to create some images and present those results to somebody, there will be questions about the gap and its influence instead of your actual results.

[maheshchamarti]

Hi,
Thank you for the Input. I tried a bunch of things but nothing seems to be working. I can email the mesh. Would be great anyone can inspect and propose a solution. Thank you.

[ghorrocks]

If you could post some images of your mesh and the gap on the forum that would be better.

[maheshchamarti]

Hi,
Please find a snap shot of the mesh. The gap ism trying to show is the radial gap between the rotor mesh OD and vane mesh ID.

[ghorrocks]

How wide is the gap?

Is it a gap or an overlap?

[maheshchamarti]

The gap is of the order of 1 micron and at other places there is an overlap.

[ghorrocks]

CFX can handle a small gap at the interface. I suspect your gap is going to be small enough that it is OK. But the only way to be sure is to run it and find out. If it is not working you will have sections which do not connect. This will be shown in the "non overlap ratio", and the flow vectors will treat it like a wall at the interface. It is quite obvious.