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How to initialize stratified temperature profile in a rectangular tank

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Old   May 11, 2015, 21:13
Smile How to initialize stratified temperature profile in a rectangular tank
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Mrityunjay sahu
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Hi,
I am working on destratification process in a tank.Air bubble plume is used to destratify.
My tank dimension is 1.44X1.44X1.12. I want to study this process by using k-e turbulence model. However, I wanted to initialize the domain with stratified non linear temperature profile through out the domain. Kindly advise me the procedure to initialize it.

Thank you in advance.
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Old   May 12, 2015, 07:49
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Glenn Horrocks
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Use a CEL expression or a 1D interpolation function to define the initial stratification profile as an initial condition.
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Old   June 11, 2015, 15:47
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munmun
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I am trying it for rectangular domain as well. I have tried to put it as CEL function. But it is showing dimension unmatched?
Could you suggest me an example?
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Old   June 11, 2015, 19:41
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CEL requires the units to be correct for it to be a valid expression. You obviously have not got the units correct. Post the CEL expression and we will have a look at it.
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Old   June 11, 2015, 19:54
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Mrityunjay sahu
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The expression I want to put in is Temperature (T) = T*(1-tanh(2*(z-h)/h)
here h = depth of tank
z = varying depth
tanh(x) = exp(x)-exp(-x)/exp(x)+exp(-x)

I am getting following error
Bad expression value 'temperature' detected in parameter 'Buoyancy Reference Temperature' in object '/FLOW:Flow Analysis 1/DOMAINefault Domain/DOMAIN MODELS/BUOYANCY MODEL'.
CEL error:
The dimensions of the argument to function 'exp' are inconsistent with expected dimensions.
Argument dimensions resolve to 'm'; expected '<dimensionless>'.

Kindly help
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Old   June 11, 2015, 21:09
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Could you please your CEL section as it stands in the software ?

If tanh(x) defined anywhere, or built-in ? or you simplified the expression for us.

I think you meant as follows

DimlessDepth = (z - h ) / h

Code:
  DimlessDepth =2*(z - h ) / h
  MyTempDist = MyTrefValue *(1 - (exp(MyDimlessDept)-exp(-Same))/(exp(Same)+exp(-Same))
In any case, the expression you are using will not work for the Buoyancy Reference Temperature since it MUST BE a single valued expression for the region. It cannot be a distribution since it will not be compatible with implementation as described in the documentation.
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Old   June 18, 2015, 11:51
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Quote:
Originally Posted by Opaque View Post
Could you please your CEL section as it stands in the software ?

If tanh(x) defined anywhere, or built-in ? or you simplified the expression for us.

I think you meant as follows

DimlessDepth = (z - h ) / h

Code:
  DimlessDepth =2*(z - h ) / h
  MyTempDist = MyTrefValue *(1 - (exp(MyDimlessDept)-exp(-Same))/(exp(Same)+exp(-Same))
In any case, the expression you are using will not work for the Buoyancy Reference Temperature since it MUST BE a single valued expression for the region. It cannot be a distribution since it will not be compatible with implementation as described in the documentation.
Thanks for your guidance.
However, I could not get your question on "Could you please your CEL section as it stands in the software ?".
Yes I simplified tanh(x). It is not built in function.

However my query is im DimlessDepth "h" is variable and it changes. Shoud I use step function or any other function to define it?

Kindly guide me. Thank you in advance.
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