Learning Forum

[SitiMN]

Hi,

I have an enquiry. When I'm doing the post-processing for my simulations in Ansys Fluent, I have found discontinuity in my contour plot (as shown in image 1 below). The discontinuity is obvious at the top-left region of my computational domain. I'm using a sliding mesh method to run this simulation and this discontinuity is observed at the interface between the rotating and stationary regions. The yellow surface in image 2 shows the interface between the internal rotating mesh and the external stationary region. Is there any way that this can be fixed?

Image 1

[Rob]

Check the cell size on either side of the interface. It'll be a result of the cell size and flow gradients.

[SitiMN]

Hi Rob I'm not sure how to do that. Can you explain further? Also, can I improve this contour plot discontinuity without changing the cell size and re-run the simulation?
Thank you.

[Rob]

Plot the mesh (all edges) on the same surface. It'll be messy but should given an indicator of the mesh. I suspect the mesh on the rotor is asymmetrical due to the presence of the outlet(?) tube.

[SitiMN]

Yes, I can see the cell discontinuity on the same surface (as indicated by the red box). This is probably due to the internal is rotating whilst the outer part is stationary, thus after running the simulation the cells do not align properly. Is there any way to smooth this in the contour plot?
Thank you.

[Rob]

It's not usually that pronounced a problem and the cell size isn't too dissimilar in the mesh image. If you replot the contour with node values off it'll highlight if you've got a high gradient in that region which can result in some distortion in the results.