[alimea]

Hi foamers
I want to calculate the value of the stress tensor in cylindrical coordinates on a boundary surface. I did it in 2 ways:

1. Calculation the stress tensor (tet3) values on the surface and transfer them to cylindrical coordinates

List<symmTensor> tet30 = tet3.boundaryField()[patchI];
List<symmTensor> tet3RT1 = Tau0;  // Initialization
tet3RT1[i].xx() = tet30[i].xx()*pow(CS,2) + tet30[i].yy()*pow(SIN,2) + 2 * tet30[i].xy()*CS*SIN;   // TauS_rr
 tet3RT1[i].yy() = tet30[i].xx()*pow(SIN,2) + tet30[i].yy()*pow(CS,2) - 2 * tet30[i].xy()*CS*SIN;   // TauS_tt
 tet3RT1[i].xy() = (tet30[i].yy()-tet30[i].xx() )*CS*SIN + tet30[i].xy() * ( pow(CS,2)-pow(SIN,2) ); 

2. Transfering data to cylindrical coordinates and calculation of stress tensor values on the surface (Suppose the tet3RT is the stress tensor in cylindrical coordinates):

List<symmTensor> tet3RT2 = tet3RT.boundaryField()[patchI];  

The obtained values are a little different! I don't know which of them is the exact value!
Do you have any idea?