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galapago October 26, 2012 00:02

boundary conditions in gambit
hi everybody

i'm trying to simulate a section of a gas turbine blade in fluent with cooling holes and for the geometry, mesh and boundary conditions i use gambit. The solution in fluent present a divergence, i think that some detail in the boundary conditions is wrong, i dont know if all the faces in my geometry must have a boundary condition (wall, interior, etc.) because i let some faces without boundary condition, also i dont know the difference between internal and interior bc. could u help me with these doubts please?

thanks in advance

-mAx- October 26, 2012 13:55

if all your domain is well connected; then you don t need to define interior or internal faces.
Also all the outer surfaces you didn t define will be regrouped as wall boundary.

Now in fluent check if all the boundaries are present in the boundary panel and check if you have some shadow-wall

galapago October 26, 2012 14:06

Max, thanks for your response

then i guiess that a bad connection is the reason for my problems, how could i check the coneectiviti in gambit?
i thinked that are well connected because all the domains sharing faces.

thanks again bro

-mAx- October 26, 2012 14:14

yes you cab check the connectivity of faces here
Surfaces should appear in pink if surfaces are connected.
Another method for checking, is picking any volume and trying to MOVE it (not copy)
If you can move it; then you have connectivity problem

galapago October 26, 2012 14:23

then maybe isn't connectivity because all my domains appear pinks. aditionally i tried to move all volumes and gambit dont let me. What do u think? is there another way to solve my problem?

-mAx- October 26, 2012 14:29

any wall-shadow in fluent BC-list?
If you stop the diverging solution, you can display the solution.Then display velocity and check if you don t have "wall" which stop the fluid flowing

galapago October 26, 2012 16:20

5 wall shadows.

i can't display velocity but i can display pressure and
nothing interrupt the fluid flowing

-mAx- October 27, 2012 11:56

display and locate wall shadows in fluent; and fix connectivity in gambit

galapago October 28, 2012 00:28

then the solution is fix the zones where wall shadows appear although there is heat transfer in those walls?

-mAx- October 28, 2012 02:59

post some pictures for understanding

galapago October 28, 2012 17:43

Hi Max

100000 thanks for your help

a short description, the fluid enters the channel with a temperature a pressure and the cooling enters the plenum and goes out to cool the blade , then there is heat transfer in the blade, the first picture show the geometry and type zones, the second one show the areas that Fluent wall shadows

galapago October 28, 2012 17:51

another doubt

the surfaces around the cooling holes must be wall oe interior? these surfaces belong to a solid and the cooling holes are fluids

-mAx- October 29, 2012 04:06

can you post first picture with shaded mode turned on?

galapago October 29, 2012 14:46

Hi Max

-mAx- October 30, 2012 03:37

I am not experienced with solid conduction, I recommend you:

Also I recommend you to simplify your physic and start without solid elements (no solid conduction).
Then when you get congerged solution, increase complexity with solid conduction

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