Influence of vortices on underfloor aerodynamics

[rccrdc]

Higher res photo

[Jef Patat]

I'd never have thought the airflow goes down like that at the beginning of the sidepod, I would have thought it to be more horizontal. Or is this because of the Y250? Anyone can shed a light on this?

[PhillipM]

There's low pressure behind the bargeboard, the intake has taken a slice out of the airflow that would normally go around the side, etc, etc. It's normal, that's how they try to seal the sides of the floor, hence the flickups you see around the edge of the floor for a few years, which seem counterproductive until you see the flow like this.

[Jef Patat]

I guess you're talking about a flow similar to this:

[henra]

I'd never have thought the airflow goes down like that at the beginning of the sidepod, I would have thought it to be more horizontal.

I'm also a bit surprised about the angle. It almost looks a bit as if it doesn't follow the undercut to the rear. Might however be just because of where they applied the flow viz. If it wouldn't follow the undercut this might be a problem because it would block off airflow to the diffuser. Would be interesting to see flow viz further downstream.

[Jef Patat]

I think it might be related to what PhilipM said and the CFD I posted. Also keep in mind that flowviz visualizes the boundary flow, the flow to the rear on top of that probably is different. Carefully check these images:
http://www.f1technical.net/forum/viewto ... 37#p386737

By all means, take my opinion as an educated guess and nothing more.

[bhall II]

Teams have been making use of the Coanda effect for years. The development of Coanda exhausts just made them better at it.

[Jef Patat]

What I'm trying to say was I expected something like the red line (deliberately red because I'm wrong) and instead we see something like the green line. It is as if that flow is pushed off the edge of the floor, there must be a reason for that. I would have expected they'd like that flow to go to the rear.

I find this aero area mighty interesting but I my understanding of it is less than 0.000001%.

@diffuser:
I know about it, I find it interesting and I don't want to explain it because I will be telling you nonsense. I'm not the correct person to add anything more to it than this.

https://tianyizf1.wordpress.com/tag/y250-vortex/

[bhall II]

It is as if that flow is pushed off the edge of the floor, there must be a reason for that. I would have expected they'd like that flow to go to the rear.

I find this aero area mighty interesting but I my understanding of it is less than 0.000001%.

All air flow between the front wheels is directed to that area in order to generate sealing vortices along the flanks of the floor. You can sorta see Caterham's version of it below (car's right, viewer's left).



To keep that air flow as strong as possible, teams don't redirect it any more than is absolutely necessary. That's why the bottom of the sidepod turning vane is positioned with roughly the same angle as the barge board.



Think of the flip-up (highlighted) as something like a little diffuser that tries to pull this air flow as far outboard as possible, because you want to seal as much of the floor as possible.

Any air flow that makes it to the rear of the car from this point is a bonus. The rest is either rolled up into that vortex, cast off and away, or completely screws up everything...

[PlatinumZealot]

They are trying to bring the centre of pressure forward I suspect.

[Abarth]

Shouldn't the g"green" flow remain more attached to the sidepod instead of leaving it on the sides, which can be seen on the floor?

[Jef Patat]

Shouldn't the g"green" flow remain more attached to the sidepod instead of leaving it on the sides, which can be seen on the floor?

You should read the post of bhall II above before asking the same question again

[Abarth]

I apologize. Somehow thought that your question was more about the inclination of the flow, but not to the fact that it leaves that region completely....
Now rereading it makes some sense, althought to me it looks like its leaving in a too big angle to remain a sealing help for the floor.

[McMrocks]

What we see in the caterham video is the vortex generated from the barge boards



from chuckdanny found in that thread: http://www.f1technical.net/forum/viewto ... 3&start=60

[bhall II]

What we see in the caterham video is the vortex generated from the barge boards

As opposed to...?

If I've implied a different interaction, it's purely unintentional.