Boundary conditions and turbulence models

Hi everyone

I am working on a shell structure and used the Butterfly plugin to calculate the wind forces.
My questions are about the two parameters defined in the outdoor airflow analysis. As you can see in the following picture, the structure is a simple shell with a thickness of 15 cm. Based on the tutorials I saw, I chose wall boundary conditions for it. Do you think this choice is correct for this type of structure?
My other question is about the turbulence model. I read several articles about it, but it is still impossible for me to choose the correct type. I found that k-ε models are better for external flow and I also realized that I should use the SST model for a more accurate calculation, but I did not find this type in the list of RAS models. Is there someone with experience who can help me in this field? (My project is a pavilion designed for a central park.)
Of course, I should mention that the main goal of my project is structural analysis, but I need to calculate the wind load to be applied in the structural analysis.

Thanks in advance for your help.

Best regards,