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-   -   "Unable to solve the local rotating region" (http://www.cfd-online.com/Forums/floefd-floworks-flotherm/106565-unable-solve-local-rotating-region.html)

Walle September 1, 2012 10:35

"Unable to solve the local rotating region"
 
Edit: This is solved. Information at the end.

Hello there! Ny name is Chris, I have been lurking the forums for a few months, but decided to register when I couldn't find an answer to my problem.

I'm trying to do a simple external simulation of a rotating fan within a short "tunnel", the medium is air.

https://dl.dropbox.com/u/655744/fan.JPG

There is a semi-transparent part that is the same diameter as the fan, as well as the same length (fan hub-to-hub length, slightly longer than the blades). I've set that part as a local rotating region, and set the speed to -600 RPM (I tried solving it without the minus, didn't change a thing). It's also disabled in the component control dialog. I've also created a boundary condition "Real wall" where I've selected all the surfaces of the enclosure, and set it to "stator".

The center of the fan is located in origo, and the fan enclosure as well as the solid for the local rotating region are concentric to the fan.

Yet, I get the error "Unable to solve the local rotating region, simulation stopped" when I try to solve it.

Any ideas what I might be doing wrong?

Thanks, Chris

Edit: I had missed that I had a hidden body in my fan model, the body I used to specify the local rotating region when I ran a simulation for the fan without the enclosure. When I suppressed that it solves nicely.

Rian September 18, 2012 19:26

Same problem: "Unable to solve the local rotating region" - Solution does not work
 
Hi there. I am really new to CFD and have only had introductory training in FloEFD. I don't know if FloEFD is suitable for my application but I'd prefer to use it if possible since my time is quite limited.

The aim of my project is to test two different configurations in a CVT (Continuous Variable Transmission) cover to find out if an inlet improves the cooling of the belt significantly. Here is a few pictures, just for clarification:
https://www.dropbox.com/s/3t2hs7fzri...Cover_Sim1.JPG
https://www.dropbox.com/s/q0mvafah4f...Cover_Sim2.JPG

The inlet will in the first configuration be closed and in the second one open to see the difference (hopefully it is large). The reason for the odd shape of the inlet is due to space limitations.

After doing a few tutorials and checking the capabilities of FloEFD, this is how I defined my system: (please comment if something is wrong)
Analysis type: External, exclude cavities without flow conditions
Physical features: Heat conduction in solids, Rotation (Local regions)
Fluid: Air and Solid: Aluminum
The rest are all default.

I created a rotating region that fully encloses the driving CVT, the CVT cover was inserted as an insulator. The boundary conditions are "Real Wall" at the CVT cover walls and "Environment Pressure" at the outlet. The inner and outer sheaves of the driving CVT were defined as volume sources with a constant temperature. This will be modified later. The only goal that was defined for now is the mass flow rate at the outlet.

After running the simulation, the error "Unable to solve the local rotating region" still appears. The rotating region has been disabled in the component control.

What may I be doing wrong/can do better? Any comments/suggestions will be really appreciated!! Even if I defined the system incorrectly.

Rian September 18, 2012 19:27

I see the images didn't post. Please open this if possible:
https://www.dropbox.com/s/3t2hs7fzri...Cover_Sim1.JPG
https://www.dropbox.com/s/q0mvafah4f...Cover_Sim2.jpg

Boris_M September 19, 2012 05:28

Hi Rian,

two things I noticed, you are using external analysis yet you close the lids. Is there a different coolant inside the CVT that has no connection to the exterior?
If this is just airflow going in from the outside and is driven by the radial fan of the CVT then you don't need any lids except maybe for the outlet if there is a pipe or so instead leading directly into the environment.
Second, what type of real wall are you using? Do you mean stator wall? There are different settings you can apply for a wall such as roughness or temperature etc.

Also it looks like your rotating region is cutting into the housing at the inlets. You will need a distance to the wall of the planar side of the housing as there are holes in the wall. Also I cannot quite see the shape of your rotating region and the rotating component in it. I think the rotating region might be defined in a bad way. If you could post some images from just the purple component with the rotating region around which is highlighted, this would help to understand how it looks like relative to the rotor.

Also, did you use gravitation and if yes in which direction relative to the axis of rotation is the vector?

Boris

Edit: Please answer in the other thread, I just saw you posted it separately again. That way we can separate it from the old problem. Thank you.


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