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Near wall treatment (k and epsilon)

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Old   October 31, 2012, 16:58
Default Near wall treatment (k and epsilon)
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Sagnik
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Hi, I want to set dk/dn = 0 and depsilon/dn = 0 at the walls in Fluent where 'k' = turbulent kinetic energy and 'epsilon' is the rate of dissipation of turbulent kinetic energy. I wonder if it can be done !

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Old   November 1, 2012, 03:55
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Yes. it can be done with the help of UDF
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Old   November 1, 2012, 04:57
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Quote:
Originally Posted by sagnikmazumdar View Post
Hi, I want to set dk/dn = 0 and depsilon/dn = 0 at the walls in Fluent where 'k' = turbulent kinetic energy and 'epsilon' is the rate of dissipation of turbulent kinetic energy. I wonder if it can be done !

Thanks
Sagnik
What are the default boundary conditions in Fluent for these variables at wall? And why you want to set these boundary conditions?
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Old   November 1, 2012, 12:02
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Hi cfd seeker, I understand there is a udf function called "DEFINE_WALL_FUNCTIONS". But that does not allow you to specify gradients of k and epsilon. Can you be a bit more specific about what UDF and whether you have seen anybody implementing it?
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Old   November 1, 2012, 12:44
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Hi far,

The default boundary conditions can be viewed at:

http://hpce.iitm.ac.in/website//Manu...ug/node510.htm


For the test case that we are designing we want to see whether it is important to model the wall properly to get the global flow features right ?

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