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Old   November 2, 2005, 12:05
Default heat transfer fluid-wall
  #1
marco
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hi, i am simulating the heat transfer of a fluid in a pipe. but i have problems how to define the boundaries. i have meshed the walls and the fluid and i defined the walls as "solids" and the liquid as "fluid" in gambit (my 2D modell looks like three rectangles on above each other)

but how do i define the boundarys. of course i have the inlet and outlet. i defined the outer lines as walls and the inner lines of the pipe as "interior". (these lines are transition between solid and fluid)

but then fluent prints the error " adjacent cell threads are of different types" (which they are, solid and fluid)

but if i define the inner lines as walls too, the i can not simulate that the wall is heaten up by the fluid because i have to set a constant temperature for a wall. that is ok for the outer lines because there is a constant temperature, but how can i deal with the inner lines of the wall? thanx for your help

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Old   November 2, 2005, 12:28
Default Re: heat transfer fluid-wall
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Mark
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Rather than specifying a constant wall temperature selct the coupled option in the wall boundary panel.

Mark
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Old   November 2, 2005, 14:56
Default Re: heat transfer fluid-wall
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marco
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hi,thank you, that works. no someone told my I should define the inner lines as "interface". i did that, but then fluent warns me as following: WARNING: Unassigned interface zone detected for interface 7 WARNING: Unassigned interface zone detected for interface 8

how can i fix that?
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Old   November 2, 2005, 16:31
Default Re: heat transfer fluid-wall
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Ralf Schmidt
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Take care that the interface between two volumes is shared by both of them. That mean: when two volume touch each other, the touching interface must be part of BOTH volumes. If not, Fluent has two faces at the same position and get confused. you end up with walls that do not belong there.

Ralf
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Old   November 2, 2005, 16:53
Default Re: heat transfer fluid-wall
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marco
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i am modeling in 2d, so my interface is a line between two faces. how can i manage, that the interface belongs to both of the faces? do i define this in gambit or fluent?
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Old   November 3, 2005, 02:11
Default Re: heat transfer fluid-wall
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Ralf Schmidt
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U have to define this in Gambit.

U can check, if you select the summarize line button and multible select the line we are talking about. Or: make a box with the mouse from upper left to lower right in that way, that ONLY the line is includet. Here, every line that cuts the box will be selected.

If there are two lines, both will appear in the selection box. In this case delet both faces (without lower geometry) as well as one of the dubble and lines and reconect them...

Ralf
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Old   November 3, 2005, 10:42
Default Re: heat transfer fluid-wall
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marco
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hi, i now realized it with defining the inner lines as walls. that works and i can calculate the heat transfer and display the heat in the different regions. now i have to calculate the drop of pressure and the shear rate within the pipe. how can i manage that? thanx

Marco

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Old   November 20, 2005, 12:34
Default Re: heat transfer fluid-wall
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gokul patil
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u can define inner wall as coupled ...
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