[AdrianMm]

Hello everyone. I am quite new to OpenFOAM and I would like to know if I could please get the advise from any of you related to the next topic:

A bit of context: I am running a Atmospheric Wind simulation, within the field of civil engineering, sort of what we do with wind tunnels tests. I have a structure imported from STL format, in the middle of a quadrilateral blockMesh and I am subjecting it to a wind. I have successfully snapped the geometry with SnappyHexMesh. I want to obtain surface pressures and pressure coefficients on my object (a building).

I am using simpleFoam to solve the model with realizableKE turbulent model. The boundary conditions are quite critical. I have used the ones from here, based on the paper from Hargreaves and Wright (2007):

https://develop.openfoam.com/Develop...ht_2007/0.orig

I have implemented these boundary conditions. Are they correct/advisable for my study? I had to cancel the “Top” wall shear since it was making my model to diverge but I don’t think this is critical. Is it?

I am experiencing some troubles to define the internalField value for “k”, in the “k” input file. My results are super sensitive to this input value and completely dependent on it (despite I thought this was just an initial setup and then the analysis is to work its way towards the right k it needs…). But no, it is critical to get this number right. From the equation k = friction velocity^2 / Cmu^0.5 I get a big number (k=8.57 obtained with rho=1.184, kappa=0.42, z0=0.03, zref=10 and Uref=22.2) leading to what I deem unrealistically huge vortices and very bad convergence. By trial and error I’ve found that the results I consider about-right are for an internalField close to k=0.1.

Can anyone make sense of all this? Which is the “k” I should be using (and why)?

Many thanks for your help. Adrian