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Old   April 23, 2012, 12:01
Default uniform Scalar,setFields
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Jian Zhong
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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?
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Old   April 23, 2012, 13:29
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Marco A. Turcios
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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
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Old   April 23, 2012, 13:54
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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
);
}
);
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Old   April 23, 2012, 14:12
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Marco A. Turcios
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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?
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Old   April 23, 2012, 14:16
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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.
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Old   April 25, 2012, 00:23
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Yogesh Bapat
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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<template<class> class ListType>
void setValuesFromList
(
const labelUList& cells,
const ListType<Type>& values
);
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Old   April 25, 2012, 11:52
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Quote:
Originally Posted by ybapat View Post
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<template<class> class ListType>
void setValuesFromList
(
const labelUList& cells,
const ListType<Type>& values
);
Hi,

Many thanks. Could you tell me more about how to use the function in the fvMatrix.H?
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Old   April 25, 2012, 23:56
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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
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Old   April 26, 2012, 13:10
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Jian Zhong
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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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