[michel1988]

Hello,
I want to set the initial field (for example, scalar field s) in a centrosymmetric computational domain (for example, a cube [-1,1]*[-1,1]*[-1,1]) with:
(1) for the region z>=0, the field is a random field.
(2) for the region z<0, s(x,y,z)=-s(-x,-y,-z).
Anyone can teach me how to realize this initialization? I am new to OpenFOAM.
Thanks.

[thomasArk47]

The quickest/simplest way is to write "hard coded" functionality directly in the code source of the solver you want to use. But dirty job!

The cleaner/right way is to use a codedFunctionObject and writing your initialisation in the read section for example. Here is an example of possible implementation:

////////////////////////////////////////////////////////////////////////////
codedInitFields
{
// Load the library containing the 'coded' functionObject
functionObjectLibs ("libutilityFunctionObjects.so");
type coded;
// Name of on-the-fly generated functionObject
redirectType codedInit;
// Compilation rules
codeOptions
#{
-I$(LIB_SRC)/OpenFOAM/lnInclude
#};
codeLibs
#{
-lOpenFOAM
#};
codeInclude
#{
#include "volFields.H"
#include "surfaceFields.H"
#include "pointFields.H"
#};
codeData
#{
// Do nothing
#};
codeRead
#{
// Name of the field to initialise
word fieldName_ = "XXXXX";
//Search the field you want to initialise in the db
Info<< "coded : Looking up field " << fieldName_ << endl;
//I suppose your field is a vectorField. Adapt it.
if (mesh().foundObject<volVectorField>(fieldName_))
{
const volVectorField& field =
mesh().lookupObject<volVectorField>(fieldName_);
forAll (field,cellI)
{
const point& p = mesh().cellCentres()[cellI];
if (p.z()>=-VSMALL)
{
//do your job
field[cellI].x() = p.x();
field[cellI].y() = 2*p.y();
field[cellI].z() = 3*p.z();
}
else
{
//assume GREAT is not used in z>0 part!
field[cellI] = 2*GREAT;
}
}
// Costly procedure... If your mesh is cartesian, uses
// associated indexation to avoid findCell.
forAll (field,cellI)
{
const point& p = mesh().cellCentres()[cellI];
if (p.z()<=VSMALL && field[cellI]>GREAT)
{
point pSym(-p);
label cellSymI = mesh().findCell(pSym);
field[cellI] = field[cellSymI];
}
}
}
#};
codeExecute
#{
// Do nothing
#};
codeEnd
#{
// Do nothing
#};
code
#{
// Do nothing
#};
}
///////////////////////////////////////////////////////////////////////

Don't forget to activate the allowSystemOperations flag in the etc/controlDict file (set "allowSystemOperations 1");

[Ben UWIHANGANYE]

Originally Posted by thomasArk47

The quickest/simplest way is to write "hard coded" functionality directly in the code source of the solver you want to use. But dirty job!

The cleaner/right way is to use a codedFunctionObject and writing your initialisation in the read section for example. Here is an example of possible implementation:

////////////////////////////////////////////////////////////////////////////
codedInitFields
{
// Load the library containing the 'coded' functionObject
functionObjectLibs ("libutilityFunctionObjects.so");
type coded;
// Name of on-the-fly generated functionObject
redirectType codedInit;
// Compilation rules
codeOptions
#{
-I$(LIB_SRC)/OpenFOAM/lnInclude
#};
codeLibs
#{
-lOpenFOAM
#};
codeInclude
#{
#include "volFields.H"
#include "surfaceFields.H"
#include "pointFields.H"
#};
codeData
#{
// Do nothing
#};
codeRead
#{
// Name of the field to initialise
word fieldName_ = "XXXXX";
//Search the field you want to initialise in the db
Info<< "coded : Looking up field " << fieldName_ << endl;
//I suppose your field is a vectorField. Adapt it.
if (mesh().foundObject<volVectorField>(fieldName_))
{
const volVectorField& field =
mesh().lookupObject<volVectorField>(fieldName_);
forAll (field,cellI)
{
const point& p = mesh().cellCentres()[cellI];
if (p.z()>=-VSMALL)
{
//do your job
field[cellI].x() = p.x();
field[cellI].y() = 2*p.y();
field[cellI].z() = 3*p.z();
}
else
{
//assume GREAT is not used in z>0 part!
field[cellI] = 2*GREAT;
}
}
// Costly procedure... If your mesh is cartesian, uses
// associated indexation to avoid findCell.
forAll (field,cellI)
{
const point& p = mesh().cellCentres()[cellI];
if (p.z()<=VSMALL && field[cellI]>GREAT)
{
point pSym(-p);
label cellSymI = mesh().findCell(pSym);
field[cellI] = field[cellSymI];
}
}
}
#};
codeExecute
#{
// Do nothing
#};
codeEnd
#{
// Do nothing
#};
code
#{
// Do nothing
#};
}
///////////////////////////////////////////////////////////////////////

Don't forget to activate the allowSystemOperations flag in the etc/controlDict file (set "allowSystemOperations 1");

Hello,


Me I want to map a cylinder on a Cartesian grid, the cartesian grid is already made and has the center(0,0,0). May you help to know hoe it is done?


I would appreciate!