miqi23 wrote:Well, there is a huge difference when the wheel is stationary and rotating when on a car.
Can you document this 'huge difference' difference or is it a gut feeling?
1) I the flow streams in the images I provided and those in the video both represent a similar technique of representing flow. There could be a reduction in detail because of the size of the video.
The images I provided came from a MSc Thesis from Cranfield University and supervised by Philip Rubini. Look him up and check out his and the departments credentials. You will be hard pressed to challenge this paper.
2) Assuming the images that I provided are correct, how do think flow around the car is going make a difference in the stationary vs rolling images?
This 'huge difference' is a fact and not a gut feeling.
Open your horizon a bit and look at it this way - (in very simple terms) when the wheel is on a car it is interacting with the front wing. A lot of effort is made to manage the tyre wake when its rotating. Getting that right is the most difficult part of F1 CFD because the tyres not only rotate, they deform as well, which creates a complex transient phenomenon. If we ignore the transient deformation for now and just concentrate on stiff tyre rotation (say carbon fibre wheels), the front wing vortices would still interact with the tyres.
Now, look at the Ferrari front wing for instance. All those add-ons you see are there for a purpose. Cutting a long story short and looking at the relevant bit for now, the separation point on a rotating tyre when on a car is way forwards (not the case when in isolation) and this results in a huge wake. That huge wake forms a unique flow signature down stream of the car and if you get that wrong in CFD, your down stream design would be wrong - simple!
I hope you get the point why your isolation cases are irrelevant.