Trying to figure out how to block a larger circle with two smaller circles
 

I'm trying to figure out how to block a larger circle with two smaller circles located at roughly its 2 and 5 o'clock positions with close proximity (see images).

CAD of geometry

Blocking

I have managed to create a good mesh for a single large circle with an o-grid. However, this new geometry is not as simple. I tried to create a large o-grid which encompasses the the main circle and the two smaller ones (which each have their own o-grids). But when trying to get a premesh it looked like this wasn't such a good idea.

The main problem is the smaller circles are located so close that when I try to split blocks around them, the splits intercept the larger circle (which I don't think will work?).

Any suggestions greatly appreciated.

Thanks,

Ollie.

Hi
 

Create an O grid on the resulting block.

Hi sameben,

Thanks for your response, I managed to figure out a blocking strategy after someone suggested one via another website. See images below for what I went with.

http://i.imgur.com/HjjjsMM.png

http://i.imgur.com/rAbZjRb.png

Thanks,

Ollie.

Hello Ollie

Can you please tell me how did you manage to generate O grid mesh. I too have a similar kind of configuration (two cylinders in Tandem, smaller cylinder followed by larger cylinder).
Any help would be appreciated.

Regards

Hi ksgr,

Generating an o-grid is fairly straight forward. It's a form of block strategy, once you create it, you need to associate edges with curves.

I suggest looking at YouTube tutorials, that's what I used to learn how to block my geometry.

Ollie.

Hello Ollie

I tried several ways but none of them were successful. I have smaller circle upstream and larger circle downstream. So when I try to create an O grid for small circle, the split block cuts the larger circle. How to go about this?

Hi ksgr,

It's your blocking strategy, try what I have suggested below. See how you must maintain continuity with your splits throughout the domain to ensure nodal placement doesn't go crazy. Don't forget to associate with the edges of the geometry.

http://i.imgur.com/ptneW5r.png

If you're still having problems, you can create the upstream mesh separately (just mesh the correct sized hole in a square domain, but ensure the cell sizes match the larger domain cells which border it). I did this for my dissertation to allow for cylinder motion, see the image below. You can then import both meshes and combine them, allowing flow through both domains. The upstream mesh (cyan) was imported and imposed onto the background mesh (the downstream cylinder).

http://i.imgur.com/gQBn4bj.png

Hope this helps!

Ollie.

Hi Ollie

Thanks for your suggestions. I will try it out and let you know if it works properly.

ksgr