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CFD_SIM November 27, 2012 07:04

Rotating of a 2D Blocking
Hey Folks,

i'm having a problem while rotating my mesh.
Just imagine a 2D channel which is symmetrical, so a rotation is no problem.
After i finished the blocking and the mesh i rotated the whole mesh by "Extrude Mesh".

But after loading it into Pre i just have one Boundary for everything. So i'm missing my Inlet, Outlet and my Walls (all defined in ICEM via Parts).

I would guess that the answer is pretty simple, but i'm not seeing ist. Does anybody has an idea?

Oh, and i tried already "Transform Mesh" but that doesn't work either.

energy382 November 27, 2012 08:39

you can just rotate the mesh in cxf pre. no need to do it in icem

CFD_SIM November 27, 2012 09:17

Yes. That's one solution, but i've seen it diffrently and would like it more if i could rotate it in ICEM and have all my parts associated to my mesh. Now its only the FLUID part that has all elements.

energy382 November 27, 2012 09:25

you can either use rotate oder mirror mesh function.

transform mesh/rotate/check copy (number of copies=1)/check merge nodes/axis=z/angle=180 (if half symmetrical)

energy382 November 27, 2012 09:26


Originally Posted by energy382 (Post 394397)
you can either use rotate oder mirror mesh function.

transform mesh/rotate/check copy (number of copies=1)/check merge nodes/axis=z/angle=180 (if half symmetrical)

you can also rotate or mirror blocking (that's the way i usually do it)

CFD_SIM November 27, 2012 09:32

I have tried to rotate my blocking, but i just had a lot of 2D Blocks aroud my rotationaxis. But no 3D Block...which looked kind of strange.

Your suggestion works if there is a 3D Blocking and i rotate this.

energy382 November 27, 2012 09:46

ah ok sorry, I thought you're talking about 3D blocking. So you've a 2D blocking?!

If so, just blocking/create block/2d to 3d/translate or rotate

CFD_SIM November 27, 2012 10:11

Yes i have a 2D Block.
I've allready tried this option a while ago but it did't get me the reslut that i wished for.

I will try it and be in touch, maybe i did some settings wrong.

Far November 27, 2012 10:44

Do you have the geometry in 3d? Can you post some pics?

CFD_SIM November 27, 2012 17:58

4 Attachment(s)
Ok, i have tried your suggestion energy382 but the result is still not the one that i was looking for.

I have attached some pictures so that you can have a look.

The first two are just a geometry that is similar to my problem and a blocking that i done real quick (so ignor the quality).
The third picture shows the blocking after i have rotated it, but i still don't have a inlet, outlet eg.

And the last picture shows the converted Mesh...problem here is that i have only a mesh in the part orfn.

Maybe i did something wrong while rotating or the geometry itself can somehow be rotated.

Another possibility would be to get a geometry that is 3D, so that i could rotate this easier...but that was not my plan and i hope we can figure it out together.

diamondx November 27, 2012 18:10

you want to define element for boundary conditions ??

while you are on the meshing tab, click on create part, select one shell, then use the flood option like "limit by curve" and assign them to inlet for example. do same for the rest, export it to fluent and it will work...

CFD_SIM November 28, 2012 06:19

Yeah ok...i tried this one too, but i can only select one element. There is no limitation by a curve, because there is no curve. Like i said, i only have a 2D Mesh. Should i also rotate the geometry?

The example that i once saw, did just have a 2D blocking with a 2D geometry, but i could not figure out how the mesh was rotated so that the boundary conditions were in place.

diamondx November 28, 2012 09:53

when rotating your block, you can check "extrude point and curve" so you can have curve... but in the post#10 i can see curves there (4th picture).
is this the button you used, just to make sure...

CFD_SIM November 28, 2012 10:06


Yes the checkbox for extrude curves and points was selected. So that is not the problem.

And i did use the right button for selecting the elements but it still didn't work. I could select all the elements by hand, but that would take me really long and i think there is an easier way :-).

Do you have another idea?

Jaiganesh S November 28, 2012 10:14

CFD - Basics
Hi all,

I have some doubts about Grid generation. I have mentioned below.

what is the difference between Physical domain and Computational domain?.. why should we use it?

What is the difference between Body fitted structured mesh and algebraic structured mesh?

Kindly reply me. Thank you in advance.

diamondx November 28, 2012 12:44

i can take a look at your project, if it' not classified of course...

CFD_SIM November 28, 2012 15:07

i think i got it today. But i'm not sure how i managed to get to this point. I will try it again tomorrow.

If you'd like i can upload my project tomorrow, but you can also just make a 2D Blocking name the parts and try it like that. There should be no difference i would think.

CFD_SIM November 29, 2012 04:28

2 Attachment(s)
So i've tried some things and i have the boundary conditions defined, like i wanted them. What made the difference was that i selected the blocks from the Screen and not like the other times only by the Blockingpart "Fluid".

But i still have a problem, mabye this has something to do with wrong settings or something like that. I did the 2D to 3D Block rotation and choosed 180 copies by an angle of 2.

When i upload the mesh into my pre i have a lot of elements that seem wrong or do overlapp.

CFD_SIM November 30, 2012 04:58

2 Attachment(s)
So i looked at the quality today and as i thought i have a lot of bad quality in my mesh (not sure how i got it, but it happend while transforming the 2D into the 3D Block).

When i klick on "Check Mesh" i get the information that there are 7949 problem elements (misoriented volume elements). So i tried to just fix that right away with the button "fix". After that process there were only 493 elements left, but i could not get them away like this.
After that i checked the quality again, but there was no change at all. The determinate is at a value of -0.999957 and the min angle is really bad too!

So no wonder that nothing is working ;-). Well after that i tried to smooth things with the "smooth hexa mesh orthogonal". The mesh quality improved a little bit, but i got triangles from not what i wanted in my mesh.

I uploaded a close up of the inlet boundary and there you see that it's not a real circle.

Maybe somebody can have a look and might have an idea.

diamondx November 30, 2012 18:18

there you go :

you can improve quality by improving the initial blocking you have done in the beginning..

here is the project :

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