[greenteam]

Hi all,

I am trying to match a reference velocity profile over a 900mm height with atmBoundaryLayerInletVelocityFvPatchVectorField by altering the z0 values in the U, k and epsilon files. I am experiencing a problem where i can match the bottom half of the velocity profile but the top half of the velocity is too high, or the opposite where i can match the top half of the velocity profile buy the bottom half is too low (please see attached image im trying to match the "reference" velocity).

Could someone please advise on what I should do?

I use paraview to find the wind profile and then find the magnitude of the U0 , U1 and U2 velocities i.e. U = (u0^2 + u1^2 +u2^2)^0.5. I'm unsure whether this is the correct method. In my U,k and epsilon files my flowDir is specified as (1 0 0). Should I be only taking U0 when trying to match the CFD wind profile with the wind tunnel profile.

Many thanks,
greenteam

[pbrady2013]

Hi,


The ATMBL class is designed for a generic case where you have no external data and you want to use a generic equation, see for example:


https://www.openfoam.com/documentati...r.html#details


In this case as you have a measured profile would a simple table BC be a better option? As a first approximation you can simply plug in your reference data. If that is not fine enough you can look at some curve fitting options to pad your table out.


Beyond that there are the usual mesh questions such as resolution and quality as your flow and energy is being transported.


Hope that helps,
-pete