A huge update to VSPAERO and OpenVSP’s support for and integration with it. This release represents ~27 months of OpenVSP development and ~18 months of VSPAERO development.
Because of the magnitude of this change (particularly if you use VSPAERO), we recommend you tread carefully. Give it a try and report any bugs, but gain some experience with it before fully committing for any serious application. This also means you should go back and repeat any validation studies you have done with VSPAERO to reestablish your confidence in it and the settings you are using.
To support the transition, version 3.44.X will stay active until the dust settles on 3.45.X.
The updates are really too many to list. For a great summary, watch the VSPAERO related videos from the 2025 OpenVSP Workshop.
To briefly summarize the changes…
VLM and Panel mode are no longer discrete choices. Instead, components can be modeled as thick or thin. The user chooses which components to model each way. We expect users will often model lifting surfaces as thin and non-lifting bodies as thick. OpenVSP performs the intersection and trimming — even in cases of thin/thin and thick/thin geometry.
The computational mesh is no longer triangle based (with approximate diagonal removal by VSPAERO). Instead, the mesh is made of polygons with an arbitrary number of edges (NGons). OpenVSP performs a cleanup process to eliminate slivers as artifacts of the intersection process.
The *.vspgeom interchange file format has been updated to v3 to support all of this (BTW, the vspgeom format was initiated back in 2020 with all this in mind, so maybe these changes go back 5+ years).
The automatic differentiation library used to create the adjoint version of VSPAERO has been removed. Its performance was unsatisfactory and it did not scale to unsteady solutions. The adjoint is now calculated via hand-coded algorithms throughout the solver. VSPAERO can now calculate a solution and 12 adjoints (6 inviscid forces/moments & 6 viscous forces/moments) in approximately the time for 6 flow solutions. The adjoint calculation is fully parallel and makes use of the multipole acceleration. As a bonus, build time on Windows is now about 25% of what it was before.
There is now an implicit wake mode that uses the adjoint to directly couple the solutions of the vortex strengths and wake position. The convergence of the explicit wake mode has also been improved, this is required for optimization workflows.
Stall is now an implicit part of the solution, better capturing the effect of lost circulation on the entire flowfield.
Wakes are now modeled with the same code as regular surfaces, including the multipole acceleration.
VSPAERO can couple with the OpenVSP C++ API to enable optimization. This is just the beginning…
I’m sure I’m missing something, but you get the idea. This is a huge VSPAERO update.
Features:
- Thick/thin intersection in OpenVSP
- Clean up of NGon meshes
VSPAERO Updates:
- Mixed thick/thin geometry support
- Hand coded adjoint
- Implicit wake formulation
- Wake sheet formulation
- Implicit stall model
- Optimization coupled with OpenVSP for geometry updates
Libraries:
- Adept differentiation library removed (faster compiles on Windows)