VW ID3 aerodynamics

[freebeard]

I question the veracity of the false color around the stagnation point. In the top view, the two outer thirds; and in the elevation the sharp gradient at the top and bottom.

[aerohead]

In Wolf H. Hucho's 2nd-Edition, he had a schematic rendering of such a feature.
It had to do with yaw-moment in crosswind and gust.
If memory serves me, in zero-yaw flow, the leading edges will provide for full flow attachment, since it's all in a favorable pressure gradient, moving towards low pressure.
In quartering crosswind, or gust, the structure acts as a burst edge, to force separation, which, otherwise, might allow bistable 'hunting' of the air beyond the nose, and potential stability issues from a larger, low leeward pressure- induced understeer.
I don't have my book with me. We'd want to double-check.

[aerohead]

Originally Posted by freebeard

I question the veracity of the false color around the stagnation point. In the top view, the two outer thirds; and in the elevation the sharp gradient at the top and bottom.

We're looking at a centerline section of the flow. Two-dimensional, in a 3-dimensional field.
Is this 'University-grade' CFD? Like Dassault's Exa Powerflow, running on a 120-core processor?

[Vekke]

Cool TUM Technical University of Munich study of ID3 containing details about the battery performance and energy consumption levels. https://www.sciencedirect.com/scienc...133?via%3Dihub

[aerohead]

According to the EPA, the closest streamline filament shown along the top of the CFD image of the VW would be your first-principle shape for body elongation.
The 'blue' region is bordered by it.
Wind tunnel smoke -flow imaging of the VW XL1 bears it out, as the closest filament remains fully-attached to the upper body for the entire length of the body, along the streamlined contour.

https://www.youtube.com/watch?v=N4KMeFwayLM