# Lecture 2 Formula SAE Car **URL:** \ **Category:** Formula Student/SAE Workshop - 2017\ **Created:** [September 21, 2017, 7:49pm UTC](https://www.simscale.com/forum/t/lecture-2-formula-sae-car/80715 "2017-09-21T19:49:05Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![dond](https://www.simscale.com/forum/letter_avatar/dond/32/5_5575768a8748004e209b776fc1b2916d.png) [@dond](https://www.simscale.com/forum/u/dond)\ **Post date:** [September 21, 2017, 7:49pm UTC](https://www.simscale.com/forum/t/lecture-2-formula-sae-car/80715/1 "2017-09-21T19:49:06Z")
In lecture 2, Milad showed the car split into two parts - an upper part and a lower part. Was the reason, that the upper part didn’t require as small elements because it only included the rear wing and the drivers head. I assume you get the same interaction between the two halves that a single, complete car would have, such as the combining of turbulence behind the car [and wing]. Is this true? Thanks. ---
**Author:** ![drodriguez32](https://www.simscale.com/forum/user_avatar/www.simscale.com/drodriguez32/32/14276_2.png) [@drodriguez32](https://www.simscale.com/forum/u/drodriguez32)\ **Post date:** [September 22, 2017, 8:48am UTC](https://www.simscale.com/forum/t/lecture-2-formula-sae-car/80715/3 "2017-09-22T08:48:35Z")
Hey @dond, Actually no, both parts need the same cell size because you will get complex flow structures due to the interaction between the air and the car. If you take a look at the mesh settings, you will see that both parts (upper and lower) have the same refinement level (i.e. same element size). This is done to observe the flow more accurately around and behind the car. The splitting of the refinement regions is done to optimize the mesh size. I hope this picture can illustrate what I mean: ![Screenshot_2017-09-22_10-45-40](https://www.simscale.com/forum/uploads/default/original/2X/d/de22b0a67864e2c2451af029fc4568eb0267bd1e.png) Hope this helps 🙂 Cheers, Diego