CFD Online Discussion Forums

Hello,

for my computations I need to precribe the velocity U by using simple functions for each of the three components (Ux, Uy, Uz). The functions should be applied to all six patches that are used and they look like following:
Ux = 2 + x^2
Uy = 2(z-x)y
Uz = 2 - z^2
To set these values to U I tried to write an application named setU, where the different functions are set to the three components of U. It did compile without giving an error message, but when I ran the applications the values were not set in U, so the file and the values did not change.
But for example when I describe U by the expression U=omega ^ mesh.C() with
dimensionedVector omega
(
"omega",
dimensionSet(0, 0, -1, 0, 0),
vector(0, 0, 1000)
);
and uncomment the three other lines, it works and the results of U = omega ^ mesh.C() are written to the six patches in the file U.
But I need to calculate the components of U by the given three functions, so can anyone tell me how it is possible to evaluate the function in each cell and then write the results to the file U?

----------------------------------- setU ------------------------------------------------------------------
#include "fvCFD.H"
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
int main(int argc, char *argv[])
{
# include "addTimeOptions.H"
# include "setRootCase.H"
# include "createTime.H"
// Get times list
instantList Times = runTime.times();
// set startTime and endTime depending on -time and -latestTime options
# include "checkTimeOptions.H"
runTime.setTime(Times[startTime], startTime);
# include "createMesh.H"
for (label i=startTime; i<endTime; i++)
{
runTime.setTime(Times[i], i);
Info<< "Time = " << runTime.timeName() << endl;
mesh.readUpdate();
# include "createFields.H"

//U = omega ^ mesh.C();
U.component(0) = 2 * factor + sqr(mesh.C().component(0));
U.component(1) = 2 * (mesh.C().component(2)-mesh.C().component(0)) * mesh.C().component(1);
U.component(2) = 2 * factor - sqr(mesh.C().component(2));
U.write();
}
Info<< "End\n" << endl;
return(0);
}

------------------------------------------------- U ------------------------------------------------------
FoamFile
{
version 2.0;
format ascii;
class volVectorField;
location "0";
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 1 -1 0 0 0 0];
internalField uniform (0 0 0);
boundaryField
{
inside
{
type patch;
value uniform (0 0 0);
}
outside
{
type patch;
value uniform (0 0 0);
}
bottom
{
type patch;
value uniform (0 0 0);
}
top
{
type patch;
value uniform (0 0 0);
}
theta
{
type patch;
value uniform (0 0 0);
}
theta1
{
type patch;
value uniform (0 0 0);
}
}