Khamsin Virtual Racecar Challenge 2015

[cdsavage]

Rear wings from round 3:

[julien.decharentenay]

Hi, I am sorry for staying out of the discussion. Things are settling down on my side so I should be able to refocus a bit more.

The submission deadline for race #4 is on the 6th August. It is next week - make sure to submit in time.

Next season. I agree that the sooner the rules are nailed down the better... On the solver front, I am starting to look at compiling my own openFoam solver for distribution, but I have to admit that I have been stuck with the setting up of the Linux environment to enable cross-compiling using Ubuntu. I will have a look with a different linux distribution in the near future with hopefully more luck....

[sjns]

@sjns: with "solver" I mean the mesher (blockmesh+snappyhexmesh) and the numerical solver (simplefoam). OCCFD is a "preprocessor" and it is working greatly, no need to change it.

You got me as you mentioned framework. Somehow I thought the term was applicable to OCCFD, though I must say the real definition seems to be a different one as my brain always expected it to be. So on the topic we do agree.

Another thought I had was the switch between high and low downforce races. This year most people probably built two cars(or almost ). The changes between Round 3 and 4 are huge. I think it would be interesting to have a realistic change of high and low down force tracks. With that in mind we could see two design philosophies during the whole season. Some cars will be better at high downforce tracks others at low downforce tracks. In addition the cars could be more refined.

Are you saying to have high and low downforce tracks in a random order rather than all high then all low?
If so, we have done that previously, it was decided to do high then low to make things a bit easier for people to with less time to configure their cars.

If you guys agreed on this format from last years experience then indeed there is no need to change it.

[CAEdevice]

Rear wings from round 3:

http://i.imgur.com/aOtZNKc.gif

What a variety of profiles!

[TalnoRacing]

If I may add an opinion: I think the current race format works well. But I think the non scoring round should in fact carry championship points. It would be nice to add more realism, but as an average modeler I would be against adding rules that increases modeling complexity, such as internal bodywork and ducts.

Perhaps a way to add realism is to have homologated parts. For example, at the start of the season each competitor submits his monocoque that he will use for the entire season. All parts submitted for each race will "attach" to the homologated monocoque. When submitting parts for a race, everything apart from the monocoque is submitted. All other parts can be developed during the season.

As with the current rules, the monocoque should completely cover the footbox and cockpit, and the SIPS template will have a fixed position for the season (each competitor may locate the SIPS anywhere within a specified area, but it cannot change after the homologated submission).

[TalnoRacing]

I am a bit stuck with an OCCFD error message and kindly ask for help.When running an analysis (I am using the "light" option for testing), I get the following error message:

"Time = 248
Divergence has been identified. Sorry we were not able to find a solution to your analysis"

What does this mean and how do I know what to fix? I only have this problem on my car for Round #4, and it is completely new, so I cannot compare it with the Round #3 car to try and identify a modelling error.

[CAEdevice]

Have you used the "very stable option"?
If yes, try with a different stl export setting or with a very small geometry change, not influencing the results.

[sjns]

Most of the times the stable version does the trick. In addition there might be a hole in your geometry. Try to load the the analysis.foam in Paraview. Switch to the latest time step( if there is one) and try to find regions of extreme pressure. Especially take a look at the max/min values.

[variante]

Hi, guys.
I'll be brief... What about asking Chris not to reveal technical images of our cars, this round? (by technical images i mean CFD and cutouts)

Chris, does it make sense?

The point of this proposal is letting everybody play their cards without the fear to reveal "ideas" uselessly (as this race won't reward points).

[CAEdevice]

Hi, guys.
I'll be brief... What about asking Chris not to reveal technical images of our cars, this round? (by technical images i mean CFD and cutouts)

Chris, does it make sense?

The point of this proposal is letting everybody play their cards without the fear to reveal "ideas" uselessly (as this race won't reward points).

I completely agree: revealing technical images (= sections, floor, diffuser, CFD post processing) after a no points race could induce someone to run with a not updated car. I think that, generally, the post race technical images would be the same for all the races (except test races), in order to reveal the same details depending only on the results.

Finally (it is my personal opinion): I think that only rendered images (excluding the floor) should be released, no CFD post processing and no sections of the diffuser and of the wings.

[LVDH]

When I saw the CFD images the first time I was very surprised and hoped that the delicate parts of my car would never appear there.
But now I think they are great. In every competition at some point you get to where few people dominate and others have difficulties catching up. Then the most obscure ways are found to manipulate the whole competition. Just look at budget caps or putting weights into the winning cars. Or being more secretive and manipulating which tire compounds will be used for the next race. And looking at the KVRC solution I would say it is one of the best I have seen so far (being forced to sell your car is also quite good). Also it helps educate and entertain other people. In my opinion it is fantastic. Also I just like these kind of nice images as a work of art and too often CFD stays behind closed doors.

Regarding the next race I do not like the no points rule but I do not see why no images should be released. On my car I am holding back a really cool device for the next races as I do not want to give it away. But I am looking forward to seeing some more crazy ideas and also the CFD visualizations.

[variante]

Regarding the next race I do not like the no points rule but I do not see why no images should be released. On my car I am holding back a really cool device for the next races as I do not want to give it away. But I am looking forward to seeing some more crazy ideas and also the CFD visualizations.

If you're holding back your ideas, why publishing detailed images? They wouldn't be of any help for the others.

I've got two choices: detroying the actual aerodynamics of my car just for this race so nobody can see or estimate anything, or racing the actual thing (pretty much) without detailed images of it being released. What's better?

BTW, if the car shown on your website is the actual car, then i'm reeaaally curious to see how it performs!

[LVDH]

BTW, if the car shown on your website is the actual car, then i'm reeaaally curious to see how it performs!

Hehe, that was the very first car. It was even far worse than the one I submitted for the first race. Even the design is pretty bad compared to now. I will have to update my page at some point.

[CAEdevice]

I've got two choices: detroying the actual aerodynamics of my car just for this race so nobody can see or estimate anything, or racing the actual thing (pretty much) without detailed images of it being released. What's better

I would choose the second option... but if you look at my front engined prototype, you could notice some of the update of the official car

[CAEdevice]

I've just submitted my car! Quite happy with the CFD results, sorry I coudn't reach that numbers (if confirmed) a couple of months ago... expecially the drag reduction.

PS: It is still a "covered wheels F1" styled shape but it is not the front engined version, but if Chris and Julien would like to make it run (off the charts), when I'll be back in a couple of days, it will be available. Anyway: I'm releasing the front engined prototype to everyone here and through Grabcad in the next days.