The yaw angle is the difference in direction between the direction of movement and the direction in which the car is pointing. A few similar topics that may go hand in hand with this study are the roll and pitch angles of the vehicle. The yaw angle is about the rotation in the z-axis (vertical axis), the roll angle is about the rotation in the x-axis (through front of the car and out the tailgate), and the pitch angle is along the y-axis (from the right car doors to the left car doors). All axis pass through the centre center of mass of the vehicle.
...
Yaw specifically comes into play when cornering or when cross-winds are introduced. The greater the yaw angle is the sharper the car turns.
...
You might be asking what does lift have to do with cars. As air moves faster around the car the a lift force is produced lifting the tip of the car off the ground as gravity is negated. We aren't building a plane so it’s probably a good idea that our vehicle doesn’t leave the ground at any point. There are a couple ways to counter this. One way being keeping the cars low to the ground will allow less air to flow underneath the vehicle thus negating the effects of lift. Another way is to just drive faster to produce a ground effect.
Another interesting and relevant topic that came up in my research is the a study that was done on rear slant angles in a wind tunnel. Here is a figure displaying the different aero bodies that were tested.
...
Below are a few tables with results from the simulations performed for this study.
...
This study can be found at this link if you are interested in seeing some of the math done to get these results: https://jeaconf.org/UploadedFiles/Document/d86c5fa8-2e77-4d47-b51d-5926832848ef.pdf
The study concluded that a 20 degree rear slant angle had the highest rating of crosswind sensitivity and a 0 degree model had the least.
Another study suggested that a yaw angle of anything greater than 12 degrees while cornering is not realistic and they did all their research based on a maximum of 12 degrees. The study goes into depth on the effect that yaw angles have of the coefficient of drag and the coefficient of lift. This is the generic vehicle model used in this study for the simulations.
...
Even though our vehicle won’t look like this, we can still see what parts are affected most by the increase of yaw angles and design our aerobody accordingly. As the yaw angle increases both aerodynamic coefficients increase. So to reduce drag and lift forces the best thing to do is to drive in a straight path wherever possible. The study compared the effects that a spoiler had on these coefficients at different yaw angles between 0-12 degrees. The spoiler greatly reduced the drag and lift at these different yaw angles.
...
Where Cd is the coefficient of drag and Cl is the coefficient of lift. The following figures shows how the lift and drag coefficient change for each portion of the aerobody.
...
In figure 7 the slant and base seem to be the components that have the most effect on drag as the yaw angle increases and the front of the vehicle has the opposite effect (probably because the front of the vehicle is pointing away from the direction of airflow at a higher yaw angle). In figure 8 the roof seems to be the component that contributes the most to the coefficient of lift and the underbody has the opposite effect. Below are some figures displaying how the surface pressure is distributed at different yaw angles.
...
Front view:
...
Downforce:
Downforce is a force that makes the car feel heavier. Downforce keeps the car from leaving the tracks and adds adding grip for better handling of the vehicle.
Sources:
...
https://www.mdpi.com/2311-5521/6/1/44/pdf
https://jeaconf.org/UploadedFiles/Document/d86c5fa8-2e77-4d47-b51d-5926832848ef.pdf
https://www.catchmentsandcreeks.com.au/docs/Race-Car-Aerodynamics-print.pdf
https://www.buildyourownracecar.com/race-car-aerodynamics-basics-and-design/4/
http://eprints.utm.my/id/eprint/84989/1/ShuhaimiMansor2019_YawAngleEffectontheAerodynamic.pdf