funkySetFields
 

Hello everyone,

Please can someone help me out. My geometry is a simple cylinder with boundaries as base, wall and top. The boundary condition for velocity field at the base is (0.5y,0.5x,0). I realized that I have to use funkySetFields in order to introduce such conditions. This I did using the dictionary option, a sample of my dictionary is

expression
(
base
field U;
expression "vector (0.5*pos().y, 0.5*pos().x, 0)";
)
it worked but unfortunately, it computed for the whole cylinder which has a total of 154000 cells.
I am presently trying to use "conditions" so that the expression is only applied at the base. I used
conditions "pos().z=0", but I keep getting an error of invalid character.

I decided to give this condition since there is no z component at the base.

Please, I need a command which applies this condition only to the base and not the whole geometry.

Thanks

You need the -keepPatches-option. Have a look at
http://openfoamwiki.net/index.php/Co...t-Room_Example
where the usage is demonstrated.

An alternative would be the groovyBC, but as your boundary condition is stationary this would be like going after mice with an atom-bomb

Thanks so much, I will look into it and hopefully I would get my expected results.

Using dictionary
 

Hi,

I installed funkySetFields last week, and have been having some fun playing around with it, on OF 1.6

I've successfully set up the dictionary version for specifying two different fluids:
simple example to make waves.

FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object funkySetFieldsDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //



expressions
(
Alpha1
{
field alpha1;
expression "1";
condition "pos().y>= 0.5";

}
);


-----------

My question is this: how would I used the dictionary to specify velocity?

I did manage to set velocity with a command line approach:

funkySetFields -field U -expression 'vector(0,10*pos().y,0)' -condition "pos().y > 0.5" -time 0

but I'd like to know how to do it via a dictionary. Whatever I tried didn't work!

TIA

The same way you did for alpha1:

Could you be bit more specific about "whatever"?

Initialize field alpha
 

Hello,

Before opening a new thread, I post my problem of initializing field alpha with expression from http://openfoamwiki.net/index.php/Co...on_Sloping_Bed right here.
When using funkySetFields, I get following error message:
Within alpha1 dict, I use zeroGradient BC for several patches. That should be OK, because setFields works as expected.
I am using swak4Foam with 1.6-ext, see header above for more details.

Maybe someone has any clue, what is wrong here?


Stefan

Hmm. Tried your expression and it works for me. I think I have an idea what happens here (an overzealous template that is convinced that surfaceFields have zeroGradient-patches) and I think I already fixed that .... just don't know when and whether it is in the latest release. Which version of swak4Foam are you using? The latest from the SVN?

Bernhard

Thank you Bernhard for quick reply, svn info of my swak4Foam states:
I will update swak4Foam and see if it works.

That is the latest RELEASED version. Try the development version (the one downloaded with hg) which is substantially newer and might (not toally sure) fix your problem (but also might have other problems)

Could this error be related to the simpleFunctionObjects-library? I did not explicitly compile this library before compiling swak4Foam.
The error only occur, if I use 'faceAverage' expression.

No. The problem occurs in FieldValueExpressionDriver which is part of swak4FoamParsers which doesn't depend on any other libraries

The problem is one of the intermediate surfaceScalarFields (when that gets created)