henry wrote:Looks to me, using confirmation bias, that Toro Rossi are doing something similar to Red Bull, sending a vortex under the floor which rotates in the same sense as the vortex in the diffuser driven by air from the slot between wheel and diffuser edge. They don't have the tyre squirt slots in front of the rear wheel because they are using the pressure there to guide the underfloor flow to the edge of the diffuser. Slots may appear to refine that guidance.
We missed the tyre squirt slots, they opened them after the initial runs on day 3 at the latest.
I have now look in detail at the STR12 floor and the outboard area is likely the most complex of any team. Personally I'm convinced that Toro Rosso is aggressively trying to create co-rotating vortexes with those longitudinal x-slots to support the once coming in from upflow. Note the shape of floor edges and structures behind them, it looks like the airflow is pushed out, forcing it to rotate.
Perhaps the wider floor leave a larger area of inboard high energy underfloor airflow which isn't manipulated by the usual vortexes, which makes such a slot more valuable. See the classic article
by Willem Toet.
If you add an additional fence or strake (a vortex generator of any design really) in each side of the floor it is possible to roll up two more vortices which take advantage of that airflow energy to create downforce. This clearly isn’t an optimised design yet but it serves the purpose of showing what might be done.
If I see high energy air exiting the floor of the car (at the most critical low ride heights), I look to find a way of using it. So, hopefully, this explains what fences in the middle of a diffuser do (some part of their function in any case).
You can see some of those vortex generator around the plank of the STR13. Basically the new floor teeths/slots would do the same for the area between floor edge and plank.
The first picture is from F1 Fanatic and the second from Willem Toet, just like the quote. He has some great stuff up in Linkedin.
P.S: The Merc teeth upflow of the floor seem to have a similar intention...