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Old   January 31, 2014, 19:35
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  #21
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Bernhard Gschaider
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Quote:
Originally Posted by maalan View Post
At last I got it!! This is an example of the correct expression... I just wanted to call the value of the field on another patch...

Code:
    {
        type swakExpression;
        valueType patch;
        variables (
            "ddtUin{INLET}=(U-oldTime(U))/deltaT();"
            "ddtV{BODY}=(U-oldTime(U))/deltaT();"
        );
        patchName CYLINDER;
        accumulations (
            sum
        );
        expression "(ddtV-ddtUin)&normal()*area()";
        verbose true;
}
Now I have another problem... I know that to set a velocity ramp at the inlet one can do it by using both the uniformFixedValue function in OF and groovyBC. Well, I would like to set a ramp with the freestream BC and it's not possible to do it with 'uniformFixedValue', so is there any way to do it with groovyBC??

Thank you so much, Bernhard!!
Best!
Of course. By using the fractionExpression to switch between gradientExpression and valueExpression you can emulate something like the freestream BC
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Old   February 7, 2014, 06:21
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Quote:
Of course. By using the fractionExpression to switch between gradientExpression and valueExpression you can emulate something like the freestream BC
Thank you bernhard, but would you mind to explain further about this BC?? I have looked for this everywhere without success!!

Best,
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Old   February 13, 2014, 19:54
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  #23
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Bernhard Gschaider
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Quote:
Originally Posted by maalan View Post
Thank you bernhard, but would you mind to explain further about this BC?? I have looked for this everywhere without success!!

Best,
I only help with technical aspects of swak/groovyBC. The physics you've got to work out yourself.

Usually the best way is to sit down with a piece of paper "If the flow goes the BC is a Dirichlet condition with this expression else a Neuman with this gradient expression". Implementing this in groovyBC is then pretty straightforward (if you understand the meaning of the phi-field - but this has been explained numerous times here on the MessageBoard and on the Wiki)
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Old   December 2, 2015, 18:32
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  #24
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Mohammad Reza
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Hello everyone
I'm facing similar problem, I want to calculate surface integral of velocity multiplied by temperature in order to compute bulk temperature at each longitudinal position of a heated pipe and therefore Nusselt number in flow direction.
Do you have any idea how to implement it by swak4foam?
Thanks in advance
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Old   December 10, 2016, 10:48
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  #25
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Dear Bernhard,

I am troubling you again...

I want to create a new/derived field and write it at the output time.

lets visualize a new volScalarField of mag(U).

I found out there three ways to do it---

1. edit the application/code (I want to omit this option)

2. using Swak4foam with expressionField. I tried the following in controlDict,

Quote:
velocityMagSquared
{
type expressionField;
//outputControl outputTime;
//outputInterval 1;
fieldName UMag2;
expression "U&U";
autowrite true;
}
I also get the output file written in the corresponding output/time directory.

But problem is paraview do not import thes new field, it do not have this information.

(also how do swak4Foam decide weather to create a volScalarfield or volVectorfield )

the last way is using coded function/dynamic code,

I tried this, by adding the following lines in controlDict

Quote:
compute_ptot
{
functionObjectLibs ( "libutilityFunctionObjects.so" );
type coded;
enabled true;
redirectType ptot;
// outputControl outputTime;
// outputInterval 1;
code
#{

const volVectorField& U = mesh().lookupObject<volVectorField>("U");
volScalarField ptot
(
IOobject
(
"ptot",
mesh().time().timeName(),
U.mesh(),
IOobject::NO_READ,
IOobject::AUTO_WRITE
),
mag(U)
);


#};
}
I neither get any new file in the corresponding output/time directory nor any visualization..

Please give me some suggesions with option 2 or 3.

I am trying this in OF 3.x and using following libraries,
Quote:
libs (
"libOpenFOAM.so"
"libsimpleSwakFunctionObjects.so"
"libswakFunctionObjects.so"
"libgroovyBC.so"
"mylibfvOptions.so"

);
Thanks,
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Old   December 13, 2016, 18:24
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  #26
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Bernhard Gschaider
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Quote:
Originally Posted by cfd@kgp View Post
Dear Bernhard,

I am troubling you again...

I want to create a new/derived field and write it at the output time.

lets visualize a new volScalarField of mag(U).

I found out there three ways to do it---

1. edit the application/code (I want to omit this option)

2. using Swak4foam with expressionField. I tried the following in controlDict,

Quote:
velocityMagSquared
{
type expressionField;
//outputControl outputTime;
//outputInterval 1;
fieldName UMag2;
expression "U&U";
autowrite true;
}
It seems I'm currently on a crusade about this: PLEASE people. Use the Code-environment (the #-icon in the message-edit-toolbar) when adding code (and OpenFOAM-dictionaries count as code) to your messages. It makes reading so much easier
Quote:
Originally Posted by cfd@kgp View Post
I also get the output file written in the corresponding output/time directory.

But problem is paraview do not import thes new field, it do not have this information.
Which flavour of paraview: the built-in reader or paraFoam? Are any messages printed to the console about problems with the files or are they just silently ignored?
Quote:
Originally Posted by cfd@kgp View Post

(also how do swak4Foam decide weather to create a volScalarfield or volVectorfield )
By looking at the valid result of a computation: in your case: inner product of two vectors is scalar. Therefor a volScalarField

Quote:
Originally Posted by cfd@kgp View Post

the last way is using coded function/dynamic code,

I tried this, by adding the following lines in controlDict

Quote:
compute_ptot
{
functionObjectLibs ( "libutilityFunctionObjects.so" );
type coded;
enabled true;
redirectType ptot;
// outputControl outputTime;
// outputInterval 1;
code
#{

const volVectorField& U = mesh().lookupObject<volVectorField>("U");
volScalarField ptot
(
IOobject
(
"ptot",
mesh().time().timeName(),
U.mesh(),
IOobject::NO_READ,
IOobject::AUTO_WRITE
),
mag(U)
);


#};
}
I neither get any new file in the corresponding output/time directory nor any visualization..

Please give me some suggesions with option 2 or 3.

I am trying this in OF 3.x and using following libraries,
Quote:
libs (
"libOpenFOAM.so"
"libsimpleSwakFunctionObjects.so"
"libswakFunctionObjects.so"
"libgroovyBC.so"
"mylibfvOptions.so"

);
Thanks,
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