[kit607]

Hi all,

I am simulating the combustion inside a turbine. I got the mass flow rate of the fuel and air. I set the massflowrate boundary condition using flowRateInletVelocity. However, I also wanted to set the radial, axial and tangential components for the velocity. Is there any boundary condition can do that?

I have looked into swirlFlowInletVelocity, swirlInletVelocity and cylindricalInletVelocity, but I not sure which 1 is suitable for me because I do not have the value for the RPM.

Thank you for you help.

[Artur.Ant]

Yes u can do it.
The way I report may be not very elegant.
In this example I know the polynomial function for the velocity field in the cylindrical coordinates system.
Once the radial, axial and tangential velocity field was calculated in cylindrical coordinates the script transform the velocity vector in x,y,z cartesian field.
Be careful with this last transformation which depends on how is rotated cylindrical system respect to cartesian coordinates system.
The BC is stationary.


Inlet
{
type fixedValue;
value #codeStream
{
codeInclude
#{
#include "fvCFD.H"
#};
codeOptions
#{
-I$(LIB_SRC)/finiteVolume/lnInclude \
-I$(LIB_SRC)/meshTools/lnInclude
#};
codeLibs
#{
-lmeshTools \
-lfiniteVolume
#};
code
#{
const IOdictionary& d = static_cast<const IOdictionary&>
(
dict.parent().parent()
);

const fvMesh& mesh = refCast<const fvMesh>(d.db());
const label id = mesh.boundary().findPatchID("Inlet");
const fvPatch& patch = mesh.boundary()[id];
vectorField U(patch.size(), vector(0, 0, 0));
const scalar pi = constant::mathematical:i;
const scalar axia_A = 1.41367332956092e-10;//coeff of polynomial function
const scalar axia_B = -4.18418721719881e-08;
const scalar axia_C = 4.91363590703797e-06;
const scalar axia_D = -0.000288677283485151;
const scalar axia_E = 0.00866669227298041;
const scalar axia_F = -0.114711359540873;
const scalar axia_G = 0.292349859167141;
const scalar axia_H = -0.768115842744353;
const scalar tan_A = -2.71884009032384e-10;
const scalar tan_B = 8.37743463345575e-08;
const scalar tan_C = -1.03086229728854e-05;
const scalar tan_D = 0.000643842539307165;
const scalar tan_E = -0.0214317483671554;
const scalar tan_F = 0.364042844487087;
const scalar tan_G = -2.70836613632716;
const scalar tan_H = 26.2627437487531;
const scalar rad_A = 2.39189261322610e-10;
const scalar rad_B = -7.37250730211115e-08;
const scalar rad_C = 9.45074247557638e-06;
const scalar rad_D = -0.000651689943666313;
const scalar rad_E = 0.0257433809501291;
const scalar rad_F = -0.553031981712577;
const scalar rad_G = 4.82541486773058;
const scalar rad_H = 7.52321045811518;
const scalar radius = 97.5;//radius expressed in mm
const scalar PIgr = 3.14159;
forAll(U, i) //equivalent to for (int i=0; patch.size()<i; i++)
{
const scalar xmm = patch.Cf()[i][0];//it considers the mesh value in m
const scalar x = xmm*1000+97.5;//it transforms the coordinates from m to mm since the mesh is in meters but the polynomial function consider mm
const scalar ymm = patch.Cf()[i][1];
const scalar y = 80-ymm*1000; //translation of the coordinate system
const scalar zmm = patch.Cf()[i][2];
const scalar z = zmm*1000;
const scalar axial = axia_A*(pow(y,7))+axia_B*(pow(y,6))+axia_C*(pow(y, 5))+axia_D*(pow(y,4))+axia_E*(pow(y,3))+axia_F*(po w(y,2))+axia_G*(pow(y,1))+axia_H;//polynomial function
const scalar rad = rad_A*(pow(y,7))+rad_B*(pow(y,6))+rad_C*(pow(y,5)) +rad_D*(pow(y,4))+rad_E*(pow(y,3))+rad_F*(pow(y,2) )+rad_G*(pow(y,1))+rad_H;
const scalar tan = tan_A*(pow(y,7))+tan_B*(pow(y,6))+tan_C*(pow(y,5)) +tan_D*(pow(y,4))+tan_E*(pow(y,3))+tan_F*(pow(y,2) )+tan_G*(pow(y,1))+tan_H;
U[i] = vector((rad*x - tan*z)/radius ,axial, (rad*z + tan*x)/radius);//From cylindrical to cartesian frame
}
U.writeEntry("", os);
#};
};
}