In this video, we’ll be looking at how to speed up the aerodynamic design process by working directly with open surface models!
Solid vs Surface models
First a few words on solid versus surface models.
In engineering, most 3D models are designed just like they are machined in real life: you start from a solid block and take away the excess material until you have the desired shape. It’s still solid on the inside and there are no gaps between the different outside surfaces.
In design or styling, however, 3d models are often built as a combination of complex surfaces: you start for example from a simple rectangular plane, which has two sides. Then you start pushing & pulling the different vertices on that plane until the shape looks good. To obtain the full 3D model, multiple surfaces are put together, sometimes overlapping, sometimes with gaps in between.
Now when it comes to aerodynamics simulations, it is typically required to work away all the gaps & interferences, to obtain something that is called a watertight or manifold 3D model. In case of surface models, this often means weeks of model fixing to obtain a 3D file that is ready for simulation.
A trick to avoid remodeling is to use a wrapping method, which will literally wrap a closed surface around your model. But this can be quite tricky, as you may end up losing small details or closing holes & small gaps that weren’t supposed to be closed, like ventilation holes in a helmet for example.
The only proper way to avoid risky wrapping methods or weeks of remodeling is to accept the surface models as they are by treating every surface like a wall on both sides. That’s exactly what we do at AirShaper – we tuned our algorithms for months to make them work directly with open surface models. Let me show you an example of how this speeds up the aerodynamic design process:
Auto Access is a company that develops & installs auto accessories, like for example hardtops for pickup trucks. In the light of more demanding emission regulations, they asked us to assess the impact on fuel consumption of adding a hard top to the Nissan NP300 pickup truck.
As you can imagine, Nissan doesn’t simply hand out their confidential 3D data. So instead we turned to a professional website for 3D car models. And as you may have guessed, these are all surface models with plenty of gaps and holes.
So instead of closing all these holes, which would have required more budget and time, we just uploaded the model straight into AirShaper. Every surface was treated as a real wall on both sides. And although air leaked to the inside in some locations, these static pockets of air didn’t affect the overall behavior of the flow.
The result? Just a day after obtaining the 3D model, we were looking at the aerodynamic report. And the best news? Adding a hardtop to the Nissan NP300 doesn’t increase fuel consumption!
So that was it for this video, if you liked it, please click the like button below and don’t forget to leave your comments!
The AirShaper videos cover the basics of aerodynamics (aerodynamic drag, drag & lift coefficients, boundary layer theory, flow separation, reynolds number...), simulation aspects (computational fluid dynamics, CFD meshing, ...) and aerodynamic testing (wind tunnel testing, flow visualization, ...).
We then use those basics to explain the aerodynamics of (race) cars (aerodynamic efficiency of electric vehicles, aerodynamic drag, downforce, aero maps, formula one aerodynamics, ...), drones and airplanes (propellers, airfoils, electric aviation, eVTOLS, ...), motorcycles (wind buffeting, motogp aerodynamics, ...) and more!
For more information, visit www.airshaper.com