Modeling wind tunnel walls in OpenVSP?

[Johannes Soikkeli]

Dear OpenVSP community,

I'm creating a validation case for a fluid solver. The solver takes an OpenVSP .stl mesh as an input. Is it possible to model wind tunnel walls in OpenVSP?

I had some initial success by creating a large ellipsoid at the root of the wing with very small thickness and then creating a half mesh:

(Half mesh because I don't want to waste computational time by calculating the other side of the ellipsoid. Also setting thickness to zero, looks good, but doesn't work, as it seems that there is still two overlapping sides and the solver doesn't like this.)

I tried to create the whole wind tunnel by creating a fuselage with empty nose and tail. However, it seems OpenVSP requires that the fuselage must be a contained volume, aka. no holes.

Any suggestions?

I'm trying to model the following wind tunnel walls:

Best Regards,

Johannes Soikkeli

Flight Performance

Delft University of Technology

Wind tunnel image from:

Sinnige, T., van Arnhem, N., Stokkermans, T. C., Eitelberg, G., & Veldhuis, L. L. (2018). Wingtip-Mounted Propellers: Aerodynamic Analysis of Interaction Effects and Comparison with Conventional Layout. Journal of Aircraft, 56(1), 295-312.

[Brandon Litherland]

Johannes,

Are you able to do any grid editing after you export the STL from VSP?  By this I mean: can you reverse the surface normals and/or trim away unwanted pieces?

Wind tunnel models have been made in VSP by placing whatever test model you want INSIDE a looped fuselage component.  For example, if the tunnel is a closed loop, you would model each section and turn accordingly until you come back to section zero.  The Loop Design Policy in the Design tab enforces the first and last section coincidence.  If you want to model a pass-through tunnel, you use Loop again but this time you would model the inner and outer surfaces instead.  Be VERY careful with the Skinning parameters when you do this.  If you simply want flat surfaces between sections, turn off all skinning by setting All Sym and unchecking "=" and "Set" for every section.

I assume that you've either written your own solver or are using some solver with viscous effects.

[Johannes Soikkeli]

Dear Brandon,

Yeah, this I am able to do. Thanks, the looping fuselage was the key! I got it now:

Yeah I'm using FlightStream.

Thanks a lot for the help!

Cheers,

Johannes