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-   -   select specific region of mesh in CFX (http://www.cfd-online.com/Forums/cfx/99996-select-specific-region-mesh-cfx.html)

payam.t April 18, 2012 02:54

select specific region of mesh in CFX
 
Hi to everyone, I am a new user of ANSYS CFX,:D


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:rolleyes:

tauqirnawaz April 18, 2012 03:39

Please go through this,

http://hikwww2.fzk.de/hik/orga/hlr/A...omains/ch1.pdf

Lance April 18, 2012 04:11

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\

payam.t April 18, 2012 05:49

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.:confused:

payam.t April 18, 2012 05:49

Quote:

Originally Posted by Lance (Post 355312)
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.

ghorrocks April 18, 2012 07:13

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.

olegmang April 18, 2012 08:04

Quote:

Originally Posted by ghorrocks (Post 355357)
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

ghorrocks April 18, 2012 08:07

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.

payam.t April 18, 2012 08:18

Quote:

Originally Posted by ghorrocks (Post 355357)
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:cool:

ghorrocks April 19, 2012 08:49

step() is in the CFX reference manual. It returns 0 if the argument is negative, 0.5 if zero and 1 if positive.

lihui54312 April 20, 2012 04:31

Quote:

Originally Posted by ghorrocks (Post 355604)
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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