[Jingxue Wang]

Hello everyone

I am trying to use atmBoundaryLayerInlet boundary to simulate the atmosperic wind field. The settings for 0 folder are attached as follows.
U：
boundaryField
{
inlet
{
type atmBoundaryLayerInletVelocity;
kappa 0.4;
Cmu 0.09;
flowDir ( 1 0 0 );
zDir ( 0 0 1 );
Uref 3.3;
Zref 0.1;
z0 uniform 0.01;
d uniform 0;
value uniform (0 0 0);
zGround uniform 0.0;
}

k：
boundaryField
{
inlet
{
type atmBoundaryLayerInletK;
kappa 0.4;
Cmu 0.09;
flowDir ( 1 0 0 );
zDir ( 0 0 1 );
Uref 3.3;
Zref 0.1;
z0 uniform 0.01;
d uniform 0;
value uniform 0;
zGround uniform 0.0;
}
But I campared with the simulated results of U and K with the experimental results. And I found the value of K is too small. I am wondering how to increase the value of K in folder 0？

Thanks a lot!

[Jingxue Wang]

Does anybody have any idea for the above question? I am really appricated for this. Thanks a lot！

[Tobermory]

If you want a higher inlet TKE, then you need to increase your z0 parameter ... but is this the right question? When you say that your TKE is too low, do you mean the TKE at the inlet is too low, or is it that your inlet TKE profile is decaying quickly with downstream distance? If the latter, then you have a different problem.

[Jingxue Wang]

Dear Tobermory

Thanks for your reply. I mean the TKE at the inlet. As you said，the magnitude of TKE is increased as the value of Z0 increases. Also，I changed the value of C2 to 9. I am not sure is it ok to adjust the values of C1 and C2? Because I found that they are unmodifiable in the user guide (https://www.openfoam.com/documentati...daryLayer.html).

Thanks a lot！

Originally Posted by Tobermory

If you want a higher inlet TKE, then you need to increase your z0 parameter ... but is this the right question? When you say that your TKE is too low, do you mean the TKE at the inlet is too low, or is it that your inlet TKE profile is decaying quickly with downstream distance? If the latter, then you have a different problem.

[Tobermory]

Yes - you can adjust C1 and C2 to give you a realistic vertical profile of TKE. The default values (C1=0, C2=1) result in the Richards & Hoxey flat TKE profile, which is a very crude approximation of turbulence in the ABL.

[Jingxue Wang]

Dear Tobermory

Thanks a lot！ I add the new values of C1 and C2 in the codes. But I found that these values doesn't work in the calculations. Do you have the similar experience for this? Thanks again.

Originally Posted by Tobermory

Yes - you can adjust C1 and C2 to give you a realistic vertical profile of TKE. The default values (C1=0, C2=1) result in the Richards & Hoxey flat TKE profile, which is a very crude approximation of turbulence in the ABL.

[Jingxue Wang]

BTW, I am confused that how to output the values of model paramters in the calculated case? I guess the valus of C1 and C2 are not changed in the calculation.

Originally Posted by Tobermory

Yes - you can adjust C1 and C2 to give you a realistic vertical profile of TKE. The default values (C1=0, C2=1) result in the Richards & Hoxey flat TKE profile, which is a very crude approximation of turbulence in the ABL.