[Nabeel Abed]

Hello everyone
I want to apply a non uniform temperature gradient around a pipe... But honestly I don't know which one is suitable... The boundaries I know are only for value not gradient like coded fixedValue, fixed profile etc...
Please could you give me a hint to do it... I am very beginnerer to the brogramming.

Anyhelp is really appreciated.
Thanks

[api]

Can you try codedMixed? I am pasting a simple codedMixed bc for pressure which will simply open and close as a sinusoidal. I do not change the gradient, but maybe you can try changing this->refGradient to the value you want in your T boundary file ..





outlet2
{
type codedMixed;
refValue uniform 0;
refGradient uniform 0;
valueFraction uniform 0;
redirectType PressBC; // name of generated BC

codeOptions
#{
-I$(LIB_SRC)/finiteVolume/lnInclude \
-I$(LIB_SRC)/meshTools/lnInclude

#};

codeInclude
#{
#include "fvCFD.H"
#include <cmath>
#include <iostream>
#include <fstream>
#};



code
#{
// this->refValue() = vector(1, 0, 0)*min(10, 0.1*this->db().time().value());
// this->refValue() = 0; // outlet
// this->refGrad() = 0; // block
// if(this-->db().time().value()% 5==0){
//
// }
//const fvMesh & my_mesh =db().lookupObject<fvMesh>;
const fvPatch& my_patch = patch();
// const fvPatch & my_patch = patch();
//const vectorField& face_center = my_patch.Cf();
scalarField& patch_press = *this;
patch_press = patchInternalField();
Info << "pressure at Patch faci I " << patch_press[0] <<endl;
//const UList<label> faceList = faceCells();
//Info << faceList << endl;
const double FREQ1=0.25; // *****!!!--->CHANGE THIS AS NEEDED!!!!
const double omega1 = 2*M_PI*FREQ1;
const scalar time_curr1 = this->db().time().value();
//const scalar time_old = db().oldTime().value();
scalar factor1 = sin(omega1*time_curr1);
//const volScalarField& my_po = db().lookupObject<volScalarField>("p");
//
//const volScalarField& my_p = this->db().lookupObject<volScalarField>("p");
//Info<< my_p[0]<<" is the pressure at cell id 0"<<this->db().time().value()<< endl;
//Info<< my_po[0]<<" is the pressure at cell id 0 at old time"<<this->db().oldTime().value()<< endl;
scalar tot_press =0.0;
scalar avg_area = 0.0;
scalar avg_press =0.0;

forAll(patch_press,pi)
{
tot_press = tot_press+patch_press[pi]*my_patch.magSf()[pi];
avg_area = avg_area + my_patch.magSf()[pi];
}

avg_press = tot_press/avg_area;
Info<< avg_area << "total_area"<< endl;

Info<< avg_press<< "averag pressure"<< endl;

if(factor1 <= 0)
{
factor1 = -1*factor1;
// factor1 =1-factor1;
}
// else
// {
// factor1 = 1 - factor1;
// }



// forAll(Cf, faceI)
//{
// this->valueFraction() = abs(sin(omega*(this->db().time().value())));
this->valueFraction() = factor1;
Info << "time =" << this->db().time().value()<< " VAlueFraction for Pressure " << factor1 << endl;
//Info << " Runtime Values in Pressure = **** = " << runTime.timeName() << endl;
#};

}

[Nabeel Abed]

Dear api
Thank you for your reply.
I have to use this boundary condition :

case hsFlux:
{
scalar R = 0.0035;

scalar theta = mesh.Cf().internalField()[cellI].y() *180.0/R;


if
(
(theta > 0) &&
(theta < 75)
)

{
scalar b3 = 0;
scalar b2 = -1.07117e-4;
scalar b1 = -8.100954e-4;
scalar b0 = 1.112046;

scalar LCR = b3 * pow(theta,3) + b2*pow(theta,2) +b1 * pow(theta,1) + b0;

gradient() = q_*LCR/(kappa);

}

if
(
(theta > 75) &&
(theta < 104)
)

{
scalar b3 = -2.544403e-3;
scalar b2 = 6.878607e-1;
scalar b1 = -5.97439e1;
scalar b0 = 1685.403;

scalar LCR = b3 * pow(theta,3) + b2*pow(theta,2) +b1 * pow(theta,1) + b0;

gradient() = q_*LCR/(kappa);

}

if
(
(theta > 104) &&
(theta < 171.2)
)

{
scalar b3 = -6.602394e-5;
scalar b2 = 3.196692e-2;
scalar b1 = -5.280388;
scalar b0 = 3.275329e2;

scalar LCR = b3 * pow(theta,3) + b2*pow(theta,2) +b1 * pow(theta,1) + b0;

gradient() = q_*LCR/(kappa);

}

if
(
(theta > 171.2) &&
(theta < 188.8)
)

{
scalar b3 = 0;
scalar b2 = 1.52459e-1;
scalar b1 = -5.488588e1;
scalar b0 = 4957.224;

scalar LCR = b3 * pow(theta,3) + b2*pow(theta,2) +b1 * pow(theta,1) + b0;

gradient() = q_*LCR/(kappa);

}

if
(
(theta > 188.8) &&
(theta < 256)
)

{
scalar b3 = 5.961826e-5;
scalar b2 = -3.504845e-2;
scalar b1 = 6.979938;
scalar b0 = -4.403785e2;

scalar LCR = b3 * pow(theta,3) + b2*pow(theta,2) +b1 * pow(theta,1) + b0;

gradient() = q_*LCR/(kappa);

}

if
(
(theta > 256) &&
(theta < 285)
)

{
scalar b3 = 2.493475e-3;
scalar b2 = -2.019052;
scalar b1 = 5.427366e2;
scalar b0 = -4.840387e4;

scalar LCR = b3 * pow(theta,3) + b2*pow(theta,2) +b1 * pow(theta,1) + b0;

gradient() = q_*LCR/(kappa);

}



Is that possible to apply?
To be honest, I am new to the programming in openfoam and facing some problems.
Thank you for your help