# uniform Scalar,setFields

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 April 23, 2012, 12:01 uniform Scalar,setFields #1 Senior Member   Jian Zhong Join Date: Feb 2012 Location: Birmingham Posts: 109 Rep Power: 7 Sponsored Links Dear foamers, I want to define a uniform scalar (e.g alpha) with 0 in some region and 1 otherwise (may use setfields utility). Also, I just want to make these values unchanged when running the code. How to deal with that in the solver?

 April 23, 2012, 13:29 #2 Senior Member     Marco A. Turcios Join Date: Mar 2009 Location: Vancouver, BC, Canada Posts: 733 Rep Power: 21 Are you trying to use this field as a source term? If you are running OF 2.1 you might be able to use the source term functionality: http://www.openfoam.org/version2.1.0/numerics.php

 April 23, 2012, 13:54 #3 Senior Member   Jian Zhong Join Date: Feb 2012 Location: Birmingham Posts: 109 Rep Power: 7 YES. My current code is : fvVectorMatrix UEqn ( fvm::ddt(U) + fvm::div(phi, U) + turbulence->divDevReff(U) == alpha*gradP ); I defined gradP as a vector and alpha as a scalar. I want to keep alpha uniform when running as follows: defaultFieldValues ( volScalarFieldValue alpha 0 ); regions ( boxToCell { box (0 0 10) (30 10 50); fieldValues ( volScalarFieldValue alpha 1 ); } );

 April 23, 2012, 14:12 #4 Senior Member     Marco A. Turcios Join Date: Mar 2009 Location: Vancouver, BC, Canada Posts: 733 Rep Power: 21 Looks like what you have is right, so long as no transport equation is solved for alpha you're in business. Are you having trouble with the current approach as is?

 April 23, 2012, 14:16 #5 Senior Member   Jian Zhong Join Date: Feb 2012 Location: Birmingham Posts: 109 Rep Power: 7 The initial alpha is right. It seems that the next time step the value of alpha is 0. I just want to keep it as the initial value all the running time.

 April 25, 2012, 00:23 #6 Member   Yogesh Bapat Join Date: Oct 2010 Posts: 45 Rep Power: 8 Hello, You might try this function in fvMatrix.H which sets values in given cells. //- Set solution in given cells to the specified values template class ListType> void setValuesFromList ( const labelUList& cells, const ListType& values );

April 25, 2012, 11:52
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Jian Zhong
Join Date: Feb 2012
Location: Birmingham
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Quote:
 Originally Posted by ybapat Hello, You might try this function in fvMatrix.H which sets values in given cells. //- Set solution in given cells to the specified values template class ListType> void setValuesFromList ( const labelUList& cells, const ListType& values );
Hi,

Many thanks. Could you tell me more about how to use the function in the fvMatrix.H?

 April 25, 2012, 23:56 #8 Member   Yogesh Bapat Join Date: Oct 2010 Posts: 45 Rep Power: 8 Hi, I think it takes list of cells in which you want to set values and list of values in those cells. So you have to create list of cells in which you want to set value of alpha. You have to call this function before solve function for matrix is called. Regards, -Yogesh

 April 26, 2012, 13:10 #9 Senior Member   Jian Zhong Join Date: Feb 2012 Location: Birmingham Posts: 109 Rep Power: 7 Hi Yogesh, Thanks. I have solved the problem by changing the definition of alpha in the creatalpha.H file similar to 'p'. Cheers, Jian

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