CFD Online Discussion Forums

CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   OpenFOAM Pre-Processing (https://www.cfd-online.com/Forums/openfoam-pre-processing/)
-   -   Non-uniform Boundary Conditions (https://www.cfd-online.com/Forums/openfoam-pre-processing/114356-non-uniform-boundary-conditions.html)

zahraa June 16, 2014 18:11

Hello,
I am new to openFoam and C++ .I want to use codedFixedValue for a wall with convection boundary condition. for this boundary i have used energy balance and with convection BC i have found following equation.


Ts= c1*(c2* Ta+Ti )

In this equation Ts is the temperature of the boundary and Ta is the ambient temperature and Ti is the internal adjacent cell temperature(internal adjacent cell which is next to the boundary) and c1 and c2 are constant.
now i do not know how i can find Ti and how i should define it here in codedFixedValue . and i should know normal distance between internal adjacent cell center and the boundary, how should i do this?

Tom123 September 8, 2015 07:41

Hello ajnewman,

I found these replies may provide a solution for the problem that I am struggling with, but I need your help as I am inexperienced in C++.

The non uniform inlet boundary condition for my problem could not be expressed in a mathmatical fomula, but only listed in a excel table that provides the coordinates and the corresponding velocity components. It is something like below:
x y z ux uy uz
1 0 0 0.1 0.6 0.8
2.5 0.1 0 0.1 0.5 2
3 0.2 0 0.2 0.7 2.8
...

The first three components tells location (z component is 0 for this surface) and the remaining three components are the velocity components.
I do not know how to apply the data to the inlet boundary condition. Any help would be greatly appreciated.

Tom

Divyaprakash October 5, 2015 03:31

timeVaryingMappedFixedValue
 
Why can't we use timeVaryingMappedFixedValue here? Although I am not too sure what does interpolation in time mean here.

AoKiji August 2, 2017 04:56

TemperatureGradient
 
Hey Guys,

im trying to solve a similar problem. My geometry is a rectengular channel with an inlet and outlet. I want to have a rising temperature on the channel walls along the channel (up and down). This is my BC 0/T:

dimensions [0 0 0 1 0 0 0];

internalField uniform 0;

boundaryField
{
inlet
{
type fixedValue;
value uniform 293.15;
}
outlet
{
type fixedValue;
value uniform 473.15;
}
up
{
type codedFixedValue;
value uniform 383.15;
redirectType UpBC;
code
#{
vector dir=vector(1,0,0);
scalarField var=patch().Cf()&dir;
scalarField value=var*100+273;
operator==(value);
#};
}
down
{
type fixedValue;
value uniform 383.15;
}
front
{
type symmetryPlane;
}
back
{
type symmetryPlane;
}
}

I only typed the code in for the upper wall but it will be the same i think for the lower wall. Now i have the Problem, that the code is compiling and running but it wont do anything while running. The up wall always got the uniform 383.15 temperature. What is wrong with the code? Do i need to start a for(....) argument?

I hope you can help me :)

AoKiji

hakolekar November 14, 2017 22:18

Hi,

I am trying to use a pressureDirectedInletVelocity as an inlet boundary condition!

However, for the same I need a non-uniform inlet angle distribution.

Is that possible in OF2.4?

It keeps on throwing an error -
compound has already been transfered from token
on line 51 the empty compound of type List<vector>


Thank you
Regards,
Harshal


All times are GMT -4. The time now is 06:38.