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3d velocity profile at velocity inlet

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Old   August 31, 2015, 05:28
Unhappy 3d velocity profile at velocity inlet
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swetha prakash
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hey all... i have to do a 3d simulation of a flow with velocity inlet. (i already have the 2d velocity inlet profile.) I am gonna have to read in the velocity profile at the inlet to do the simulation but i have no idea how to generate one. the flow is a turbulent velocity profile fully developed. i am not sure how to generate one.
is it like we have to give a user defined function in fluent or we can manually calculate it and edit the .prof file and read it in fluent.

the question might be dumb. but i am not quite familiar with ansys fluent.
thanks
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Old   August 31, 2015, 13:46
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Lucky Tran
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I think the best way is to generate the profile using Fluent from a periodic simulation to get your fully developed velocity profile solution. Then export the profile at the periodic boundary (export the .prof file). Then import the profile onto your simulation. Actually you should also export/import the turbulence quantities (k, epsilon, omega,etc.) and any other important quantities (temperature,etc) since these are also needed at the inlet.

Even if you don't use Fluent to generate the profile, I still think the easiest way is to generate some type of .prof file and read it into Fluent. The .prof is just a table of x,y,z u,v,w,t,k,epsilon values. The .udf approach does not add any value or utility to defining the inlet velocity bc's.

But make sure you also get the turbulence quantities, they are just as important as having the right velocity profile.
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Old   September 1, 2015, 02:38
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swetha prakash
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thank you sir.. but i actually have only the mean value of velocity at the inlet. are you suggesting that i use the mean value at the inlet in fluent for the flow and get the velocity profile and other turbulent quantities after running it and exporting the .prof file and then using it again as inlet condition?

still confused.
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Old   September 1, 2015, 03:10
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Quote:
Originally Posted by LuckyTran View Post
I think the best way is to generate the profile using Fluent from a periodic simulation to get your fully developed velocity profile solution. Then export the profile at the periodic boundary (export the .prof file). Then import the profile onto your simulation. Actually you should also export/import the turbulence quantities (k, epsilon, omega,etc.) and any other important quantities (temperature,etc) since these are also needed at the inlet.

Even if you don't use Fluent to generate the profile, I still think the easiest way is to generate some type of .prof file and read it into Fluent. The .prof is just a table of x,y,z u,v,w,t,k,epsilon values. The .udf approach does not add any value or utility to defining the inlet velocity bc's.

But make sure you also get the turbulence quantities, they are just as important as having the right velocity profile.
Actually i just have the mean value of velocity at the inlet. thats all i have. i have to read in a velocity profile and other quantities at the inlet. and i have no clue how to do that. i suppose i have to give the mean velocity at the inlet as a constant parameter an run it once to get the profile and then export it as .prof file and then read it????

I am still not clear on what to do. thats why.. sorry..
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