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select specific region of mesh in CFX

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Old   April 18, 2012, 02:54
Default select specific region of mesh in CFX
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Hi to everyone, I am a new user of ANSYS CFX,


I want to select specific region of mesh and fill this region with specific values of pressure and temperature as initials values, how can I do this in CFX? Any ideas welcome
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Old   April 18, 2012, 03:39
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Please go through this,

http://hikwww2.fzk.de/hik/orga/hlr/A...omains/ch1.pdf
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Old   April 18, 2012, 04:11
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That link refers to an old manual. Instead, see the pdfs that come with the installation (or the built in help).

Read the tutorials in cfx_tutr.pdf. You'll find them at:
<installation root>\ANSYS Inc\v140\commonfiles\help\en-us\pdf\
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Old   April 18, 2012, 05:49
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My prbolem is NOT inspecting boundary conditions! I want to choose a certain zone of mesh(for example a circular zone) and assign certain pressure and temperature in that zone and initialize problem.
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Old   April 18, 2012, 05:49
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Quote:
Originally Posted by Lance View Post
That link refers to an old manual. Instead, see the pdfs that come with the installation (or the built in help).

Read the tutorials in cfx_tutr.pdf. You'll find them at:
<installation root>\ANSYS Inc\v140\commonfiles\help\en-us\pdf\
My problem in NOT specifying boundary conditions! I want to choose a certain zone of mesh(for example a circular zone) and assign certain pressure and temperature in that zone and initialize problem.
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Old   April 18, 2012, 07:13
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Use a CEL expression to define the region, eg a = step(((1[m]-abs(x))/1[m]) selects a strip -1>x>1 to have a=1, elsewhere a=0. You can use this to define initial conditions and boundary conditions.
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Old   April 18, 2012, 08:04
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Quote:
Originally Posted by ghorrocks View Post
Use a CEL expression to define the region, eg a = step(((1[m]-abs(x))/1[m]) selects a strip -1>x>1 to have a=1, elsewhere a=0. You can use this to define initial conditions and boundary conditions.
Dear Glen. I'm interested in this thread too. But i'm not sure if it is possible to choose some part of the mesh on the curved surface to be able to set new boundary conditions. Is it possible?

Regards, Oleg
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Old   April 18, 2012, 08:07
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You have access to all the volume and faces defined in the mesh file if you look in the feature tree. But if the volume or face you want is not defined int he mesh file youhave to either remesh to include it or define it another way such as using CEL.
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Old   April 18, 2012, 08:18
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Quote:
Originally Posted by ghorrocks View Post
Use a CEL expression to define the region, eg a = step(((1[m]-abs(x))/1[m]) selects a strip -1>x>1 to have a=1, elsewhere a=0. You can use this to define initial conditions and boundary conditions.
Dear glen,thank you for your perfect answer, but I have another question,what is the mean of "step()",I couldn't find it in CFX help

Last edited by payam.t; April 18, 2012 at 08:55.
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Old   April 19, 2012, 08:49
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step() is in the CFX reference manual. It returns 0 if the argument is negative, 0.5 if zero and 1 if positive.
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Old   April 20, 2012, 04:31
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Quote:
Originally Posted by ghorrocks View Post
step() is in the CFX reference manual. It returns 0 if the argument is negative, 0.5 if zero and 1 if positive.
But you must know a point,a bout step() function, step() just back to three value,0,1,0.5,but about the step(x),this x, you must know this value not real value,just floating point.If the floating point locate nearby the value zero, and want to use the step()function, must use interpolation method to sovle it.
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