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-   -   simple Gambit face geometry (https://www.cfd-online.com/Forums/fluent/38940-simple-gambit-face-geometry.html)

jdb December 14, 2005 22:08

simple Gambit face geometry
 
I tried searching the forum, but didn't find a lead. I'm trying to create a 2D axisymmetric GAMBIT model composed of a large cylinder with small spheres along its central axis.

I created a long 2D rectangle and will define one long edge as the axis of symmetry (thereby making it a cylinder). I placed two circles along this axis, such that their areas are split in half by the rectangle edge. Next I subtracted (and did not retain) the two circles. What I'm left with is the rectangle with two semi-circular "bites" taken out. So far, so good.

What I want to do next is give each semi-circle a diameter (line) so that the semi-circle is closed to form a volume. I created the diameter line(s), but cannot figure out a way to "stitch" (not sure if that's the right word) the diameter to the perimeter (trying for a semi-circular closed area). I tried the "connect edges" button but that failed. I tried "merge edges" but that failed. I tried "merge faces" but it only shows the rectangle face and not the diameter(s).

Ultimately I want to give the cylinder volume one property (liquid), and the semi-circles a different property (liquid). Any advice on this simple little stumbling block? Unfortunately someone borrowed the help manual last summer and didn't return it!

Jeremy December 15, 2005 15:23

Re: simple Gambit face geometry
 
I am not sure if I completely understand the situation, so my answer my not be helpful...

If you would have retained the circles when you subtracted the them from the rectangle, you would have ended up with three areas, one for the rectangle, and one for each of the circles. When importing this into fluent you should be able to define the two half circles (the spherical volumes) as one liquid and the rectangular area (minus the half circles) as another fluid.

I hope that helps, then again, I am not too clear on the geometry.


jdb December 15, 2005 15:49

Re: simple Gambit face geometry
 
It seems you generally understand my desired 2D setup, but I see two issues. (1) In past models when I used 3D, I did not retain the spherical volumes. The reason is that I only want to define a single "interior" boundary condition around each sphere. But if they're retained, then there end up being two faces side by side (the rectangular area's "cutouts" plus each sphere face). Isn't that a problem?

(2) If I retain the *full* circles, then it seems there might be some confusion because half of each circle would cross over the axis of symmetry. I assumed that wasn't allowed...


Jeremy December 15, 2005 16:35

Re: simple Gambit face geometry
 
(1) I don't think this is a problem, I believe they will simply share the face when imported into Fluent, but I can not say for sure without doing it.

(2) You can create two rectangles, one in the -ve area and one in the +ve area. Use the -ve rectangle to cut the spheres in half, not retaining the area. Then in the positive area you can subtract and retain. This will ensure that everything is in the +ve quadrant.


Jason December 17, 2005 10:40

Re: simple Gambit face geometry
 
Instead of subtracting the circular faces, split the rectangular face with the circular faces (do not use the retain option). This will leave the rectangular face with the two semi-circle bites removed, and the two semi-circle bites will also remain there.

Good luck, Jason


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