When you get to the sim setup for turning flow around the car, I have some ideas on that… Do you have a sim run for turning flow you can point me to from last year?
yea i can send you the link to last years simulations. Were you thinking the MRF style cylindrical style wind tunnel. I read that thread
1 Like
Yes, MRF… If you want to keep it private, just share the private one with me…
COOL, I can play with that 
Since you guys only saved your forces results every 5 iterations last year, I had to use ORSI 100i30mai to make it give similar results to every iteration saves:
This brings up a point, for ORSI, only ONE forces (preferably a coefficients) results item of all faces needs 1 iteration saves… For any others, there is no problem making them save every 5 or more (unless you want to ORSI them accurately, which you probably do, so you can ignore this note that could save core hours…), which would save core hours during the sim run…
EDIT: What FSAE team are you with and how did you do last year 
Also, you really should try my MRF idea…
So based on the ORSI of the last years car, we did have 1% stability in the results… thats good to know
Yes for the coefficients i will do 1 iteration saves. I do have a decent amount of core hours, I dont plan on using a lot as i need to do maybe 10 -15 full car simulations total.
I am with the FSAE team Raceyard from Kiel Germany, The account is Raceyard53 as you have probably seen. We did ok last year, there are always problems with the car working properly/being completed on time. The team has a lot of advanced systems but isnt very good at time management or keeping deadlines. This caused the 2018 car to not run at any events and last years car only started working towards the end of the season. Its too bad because we loose a lot of points at the design events due to having nothing on the car validated.
I would love to try your MRF idea. I read also the Curved wind tunnel thread Cornering Aerodynamics with Simscale
And the PDF within this thread Here
In the PDF it shows the following graphs towards the end. While i would love to experiment with the model in a curved wind tunnel, I have a few reasons NOT to peruse this test which are explained at the end.
With this summary at the end;
Summary
The cornering condition can have a significant effect on aerodynamic
performance of vehicles but is unable to be represented
experimentally. Experimental solutions developed for dynamic
motion of aircraft are not readily adaptable for automotive bodies.
The close ground proximity, high blockage ratio and the specific type
of motion all add complexity which increases the difficulty of
achieving the required flow conditions.
Fortunately numerical simulation permits investigation into the
condition. However aerodynamicists must remain aware of the
change affected by this condition. Numerical simulation must
accommodate curved flow occurring within a non-inertial reference
frame, and this requires additional considerations when constructing
such models. Due to the motion, drag begins to act in a curved path
and variation in Re occurs within the domain. Results highlight the
importance of adopting the correct analysis techniques when
evaluating aerodynamic performance for cornering vehicles.
Reasons not to do Curved wind tunnel test
- This difference in data, to me, seems fairly minimal in comparison to a straight wind tunnel.
- These tests on the Ahmed body are at 25 m/s. This is quite fast for what our car will be seeing on the track. My tests would include-
a. Official skid pad event inner radius at 7.625 meters
b. Low speed skid pad test at around 4-5 meters
c. High speed skid pad test at around 10-12 meters
-
(cont.) Therefore, outside of the higher speed skid pad, i do not see our cornering speed exceeding 20-22 m/s as most of the turns on the FSG track are slower speed turns. I have been using 18.06m/s for previous inlet velocity tests because this is the average speed for all turns on the track. Optimizing the car by simulating low and high speed cornering situations was not possible last year because i was the only one in the Aero team for the design phase. I simply didnt have enough time.
-
Speaking of not having enough time, my last reason is just that. If we can justify that a straight on simulation ( including the pitch, yaw, roll, and steering input changes for each skid pad trial) are enough to have accurate results within reason. I would vote to leave it as a straight wind tunnel simulating the car in those pre-set cornering angles.
Basically - is this worth the trouble? Are the results that much more accurate that we NEED to do this?
Let me start a simple project to explain and test the MRF setup that I have suggested for cornering flow analysis…
At that point can answer your questions…
Then I will start a new topic on that where we can have another record length discussion on it 
I mean if YOU wish to proceed with this test, while i continue with the same cornering simulations in a straight wind tunnel then we will have an excellent data set.
I just dont want to commit to this extra work when i still have the rest of my research for vehicle dynamics to do, get the car prepped for testing, and start writing the damn thing. I really dont want to make this stressful at the end.
P.S. I still really do want to do the curved tunnel
EDIT: I should really send you the full solidworks car model. I designed it with adjustable suspension so changes to geometry can be made quickly The tutorial for what i did is here
No problem, parallel is good…
EDIT: Rhino imports Solidworks fairly well, or I can steal your 2020 wheels turned geometry at some point from a SimScale project if it is step format imported…
Ok whatever you want. If you have the original file you can change the pitch, roll, yaw, ride height, and steering angles to whatever you want. Im not sure if an imported STEP can do that. Either way ill be importing the cornering geometries for each case in the next couple weeks.
1 Like
Give me an approximate turn radius you want please…
Official FSG skid pad size for 2019 is:
7.625 meters inner radius
3m track width
so
Approximate center of car radius is
9.125m turn radius
Wow, small, what speed are you hoping to drive around that with all this downforce you have (without drifting or do you drift too)?
haha no drifting, although that would be sweet. Im not exactly sure what speed yet i have to talk to who was in charge of last years vehicle dynamics development. This is where i have to decide to do real world testing first, then use that data to as inputs to the CFD or vice-versa. I can get approximate data for this but the goal is improving our times/lateral acceleration not just comparing results
Just a rough speed for now is OK…
WOW here are the 01234 U plots, very interesting (I will add layer lines soon, they take time as I have to draw them):
.
.
.
.
wow this is awesome. Three things i notice.
-
Looking at the underside of the wing, the separation location is about the same for 4,3,2, layer sims but in the 1 layer sim it stays attached longer.
-
Looking at the outbound wake direction (far right of the picture) i notice that 3 layer and 1 layer are turned more upwards, while 4 and 2 layer are straight or downward facing.
-
At the bottom of the wing, where the Dark red area is around the gray area, in the 4,3,2 layer tests this dark red is about the same size while in the 1 layer it grows bigger
Any thoughts on this or would you consider this just variations in flow?
I am not sure but the 0 layer obviously has to be significantly different because of the major difference in CD and CL with ANY layered mesh…
I am showing the full solutions sets at the iteration that closely matches ORSI values, so that removes that issue (some even match to 4 significant digits 
)
The CD and CL of all layered meshes are pretty close to each other and I don’t know if we are seeing true differences between # of layers in the U mapping or flow patterns yet… I hope we are, as that would be awesome…
What I find really interesting is the fact that 0 layer flow is almost not separated at all!!! (just a little in the camber area)
Yea i forgot to say that your ORSI% difference values are spot on!!
Im not sure if its flow patterns or not, but for me… three simulations have one point of separation, and one has a later point. Unless this is a fluke, this points to something. Maybe running the 0,1,2,3,4 test again with the wing at a different AOA? See if the pattern of later separation for the 1 layer simulation is still there?
AHA, more reason to do a dual test on existing car, cornering speed and do some INVALUABLE tuft grids at fixed speed here too 
yes the tuft test will most likely be done first at a straight line run for a basic setting. Then at each skidpad radius and comparing the best overall setting. We can change the AOAs for each event though.