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I thought it would be good to share a project I have been working on. Although very beautiful I have always felt the Z4M styling could do with a little more aggression, especially the front. I decided to design and develop my own splitter and canards for more of a CSL/GTS appearance. Having been able to reverse engineer the car over the last year with use of photogrammetry I am approaching the development slightly differently by utilising computational fluid dynamics simulations. Below are two pictures of the reverse engineering model and the base CFD simulation
So far I have run three different splitter iterations and got up to 12 kg more downforce at 180 km/h.
The design will keep evolving for aesthetic reasons and to try and extract more aerodynamic performance out of it. Next up is the first simulation of the canards. I would be great if you could share your feedback, experiences and thoughts!

For those who are interested a few more details are available in the thread I started on ZPOST: http://www.zpost.com/forums/showthread.php?t=1484233

Interesting.
What did you use to create the zed mesh?
And which CFD software did you use and did you take different air-densities/temps into account?
I've used ANSYS CFD for modelling hydrodynamics on ship hull designs and specifically for thruster nacelles and pods. Takes hours to simulate for different climates / sea conditions! Even using distributed computing.

Awesome stuff! As an engineer it's great to see someone taking such a thorough approach to the topic!

What's the limit of added downforce that can be reached just with the addition of relatively subtle (relative to something like a giant wing on the boot!) parts like these?

Nice stuff!
My hands-on approach resulted in this spoiler, which together with the Eibach springs made the front end a LOT more stable at 260km/h on Autobahn etc.

So much that I actually had to come up with a stabilizer bar in the middle of the floorpan, because after every speed run it had buckled down! (I suppose from the downforce generated.) So that I think will be your next mod too!
(2 small holes & a long ziptie to the fan chassies would work too obviously)

nice to see such a professional post.

Very nice! Also, I didn't realise they did them in gold or tvr style flip paint.

Shut up and take my money.

Beedub wrote: ↑Tue Apr 24, 2018 9:57 pm Shut up and take my money.

ditto

Chris_D wrote: ↑Mon Apr 23, 2018 11:18 pm Interesting.
What did you use to create the zed mesh?
And which CFD software did you use and did you take different air-densities/temps into account?
I've used ANSYS CFD for modelling hydrodynamics on ship hull designs and specifically for thruster nacelles and pods. Takes hours to simulate for different climates / sea conditions! Even using distributed computing.

Thanks for the reply Chrid_D! Sounds like some interesting projects. Where the hull simulations multiphase?

I am using open source software for all of the simulation work. Because my simulation is below Mach 0.3 the compressibility effects are generally negligible. However, there are obviously various heat sources and heat exchangers which have an influence on the surrounding flow. Based on the flow paths and the parts of interest being either quite far away from this flow or upstream I have made the appropriate efficiency trade-offs. The simulation already takes a good day to solve with this in place!

Mangozac wrote: ↑Tue Apr 24, 2018 12:51 pm Awesome stuff! As an engineer it's great to see someone taking such a thorough approach to the topic!

What's the limit of added downforce that can be reached just with the addition of relatively subtle (relative to something like a giant wing on the boot!) parts like these?

Thanks for your reply Mangozac! Good question and not an easy one. Based on the initial runs, the local improvements I anticipate the final version to have a few dozen kg’s of downforce from the splitter and canards. I found some data on commercially available universal RW’s. At moderate angle of attack the mid-range option is said to make around 120 kg scaled to the speed I am testing at. When the whole underfloor is designed correctly it can easily outperform such a wing in terms of raw downforce but also efficiency (downforce vs drag.)

Thanks everyone else for the replies! I thought I get some GULF inspired colours out there on the options Are any of you guys running aero bits on your Z4? Looking good Argenta, what material did you make it from?

Thanx! Its rubber, generic ebay spoiler rubber profile that’s been cut/sanded to fit.

I look forward to your final product!

I managed to run the simulation of the first draft canard. I positioned and shaped it to complement the lower line of the side ducts.
Aerodynamically it is doing what it is supposed to. It raises the static pressure on the top surface and increases the suction underneath. This pressure difference yields the formation of a vortex which when working correctly will help manage the wheel wake. Unfortunately although aerofoil shaped, the suction on this first canard iteration is very peaky and too much on the nose of the element. The by-product is that the vortex health is suboptimal and dissipates too quickly.
There are some good opportunities to improve the aerodynamic properties drastically by redistributing the pressure and managing the vortex strength. This will benefit the local performance and downstream influence.

What do you guys think? More to come!

I have no comments of value to provide, but I'm really enjoying seeing this process so please continue to share!

There has been a nice influx of talented b*stards recently.

Having briefly been involved with some wind tunnel tests a few years back, I’ve become very skeptical of any ‘aero’ mods performed by most enthusiasts, so seeing this kind of work being performed on our platform really is great to see

Do you plan to do any work on the side ducts that vent in to the wheel arch or plan to experiment with other areas of the body?

Also,I don’t suppose you scanned the underside of the car by any chance? Would the scan data be useful enough for simulations?