Khamsin Virtual Racecar Challenge 2014

[machin]

OK, slightly different format to last years charts:-

Cd.A along the bottom and lap time on the right. The lap times assume you have COP=1.83m behind the front axle. The shaded area represents Cl.A ranging from 2.8 along the lower edge (light blue) and 2.0 along the upper edge (dark blue).



You can see from the fact that the lines of equal Cl.A are very flat that drag has little effect on lap time around Monaco: so you should be concentrating on achieving high downforce.

[astracrazy]

Sorry guys been away and catching up

Chris good idea i will look into including something in section 10 about submission rules

Matteo the rule means the intake in its entirity must be visible from the front of the car unless by the things specified i.e suspension. So your front wing cant block it

[cdsavage]

I use 1.225kg/m^3 (15degC @ sea level)

I'll generate some charts for you guys. I'll start right now as I see you have very little time for your first race submissions!

Thanks.

A question for anybody who has run a simulation on their own machine with either the provided skp file (with the front and rear wing groups) or from using the portal: What is the total number of cells that you have if you look in analysisoutput.txt under "checkMesh"? Im trying to work out if a boundary layer mesh is being generated.

[RicME85]

Using last years 100mph no yaw tunnel I got this:

Mesh stats
points: 549768
faces: 1350654
internal faces: 1209661
cells: 404277
boundary patches: 13
point zones: 0
face zones: 0
cell zones: 0

Looking in the scenario_0 folder (the one from the portal) I dont seem to have analysisOutput

[CottrellGP]

Hi guys me again (pain) i have ran my model through khamsin and i have the results, but i have no idea how to check the results or see the flow lines over my model, the only way i can load it in paraview if it is an .stl,

Either that or i need a dummies guide how to start the analysis and how to analyse the analysis, because there are that many different things on here i am just confused!

[astracrazy]

when you import your model (click apply) you need to change the time (along the top) to the highest number. Mine is usually just 1. This is kinda like 0 = before 1= after (simple explanation)

you should then have the flow line icon coloured (not greyed out). If you look at the icons at the bottom of the menu right under 'Solid Colour' drop down box - it starts with one that looks like a calculator. The stream line is 8th one along (looks like flow lines going around a circle).

Its then just a case of playing around with the options this gives you.

[CottrellGP]

when you import your model (click apply) you need to change the time (along the top) to the highest number. Mine is usually just 1. This is kinda like 0 = before 1= after (simple explanation)

you should then have the flow line icon coloured (not greyed out). If you look at the icons at the bottom of the menu right under 'Solid Colour' drop down box - it starts with one that looks like a calculator. The stream line is 8th one along (looks like flow lines going around a circle).

Its then just a case of playing around with the options this gives you.

I have it working! =D> but the flow lines seem to just go through my model, i will try work out why

[astracrazy]

your importing yours as a .stl? i don't know how you have done yours

i just usually in khamsin right click-> analysis -> paraview and it opens it for me as a foam file. I change the time to 1 then click accept then change the opacity to 0. This loads the tunnel. I then right click on the big white menu tree on the left and open and new one by selecting the foam file but select to just load the car (there a few check boxes listed for different things) and this loads the car only

if you want i'll send you a tutorial of how i do mine? pm me. I can post if on here after but everyone has there own way i guess

[CottrellGP]

your importing yours as a .stl? i don't know how you have done yours

i just usually in khamsin right click-> analysis -> paraview and it opens it for me as a foam file. I change the time to 1 then click accept then change the opacity to 0. This loads the tunnel. I then right click on the big white menu tree on the left and open and new one by selecting the foam file but select to just load the car (there a few check boxes listed for different things) and this loads the car only

if you want i'll send you a tutorial of how i do mine? pm me. I can post if on here after but everyone has there own way i guess

Hello, IM ALL SORTED! FINALLY! after hours of messing around i can finally do an analysis the same way you do yours, but now two questions, how do i find out my drag and downforce and how do i save the file so i can keep opening it?

[astracrazy]

providing before you ran the sim you Right-click->Define->Monitor Forces then in khamsin right click -> analysis -> output. it opens a text file. scroll down and find something like

forces(pressure, viscous)((34.7833 1386.02 -3085.12) (-0.0607569 2.13449 0.410286))

in bold = drag and downforce

[RicME85]

Oh Dan

All this was covered in my post that summarised CFD and analysis.

[CottrellGP]

I am all sorted, i have it all under control now, I've emailed Julien for some advice on a couple of things, no surprise ill be asking you guys for help again next week. But anyway thanks for the help you have given me!

[cdsavage]

Hi, I have a question about sidepods intake. When the rules says: "Any inlet must be visible in its entirety when viewed from the front of the car (ignoring the front wheel/suspension assembly). The area of each intake must be at least 45000mm^2" it means that I have to consider or not the portion of the intake that is hidden by the front wing?

I was thinking about this rule and you are right, it doesnt make much sense to require that the sidepod intake isnt obscured by the front wing. Maybe for round 2 the part "ignoring the front wheel/suspension assembly" could be changed to "ignoring the front wheel/suspension assembly and front wing".

[CAEdevice]

Hi, I have a question about sidepods intake. When the rules says: "Any inlet must be visible in its entirety when viewed from the front of the car (ignoring the front wheel/suspension assembly). The area of each intake must be at least 45000mm^2" it means that I have to consider or not the portion of the intake that is hidden by the front wing?

I was thinking about this rule and you are right, it doesnt make much sense to require that the sidepod intake isnt obscured by the front wing. Maybe for round 2 the part "ignoring the front wheel/suspension assembly" could be changed to "ignoring the front wheel/suspension assembly and front wing".

I think that from a technical point of view you are right, but I don't know if most of the team would agree with changing the rules now, maybe it would be better to include this point next year or after a longer time (two or three races).

[CAEdevice]

providing before you ran the sim you Right-click->Define->Monitor Forces then in khamsin right click -> analysis -> output. it opens a text file. scroll down and find something like

forces(pressure, viscous)((34.7833 1386.02 -3085.12) (-0.0607569 2.13449 0.410286))

in bold = drag and downforce

Just a curiosity (I'm going to use Khasmin only after the first race, I'm too late at the moment): the first number (34.7833) is the lateral resultant (near to zero)? And the numbers in the second group are the postition of the resultant forces (so 2.13449 should be the COP)? Is that a Monaco 2013 setup?