Will these strakes cause more drag ?

[freebeard]

My panel van, with the fiberboard partition behind the seat had the best heat, even with the twist knob control. The space was about the size of a phone booth. A 'hot box' if you will.

[Cd]

Originally Posted by M_a_t_t

We're you thinking a scaled up version of this? This is the newest honda fit btw

Yes. Something similar.
I'm fairly certain air just goes right over those gutters , and that it does not direct airflow.

I'd love to be wrong though.

[M_a_t_t]

Do you have any tuft testing from the wind shield without the fence in place? I did one on my car and the air is almost horizontal right around the wiper, which might explain the collecting of snow and the massive turbulence that was described earlier.

I might take you up on the opportunity and propose a v. 2.0 and try it on my car to see what happens.

@1:47 Is when you can see the near horizontal tufts on my car. Notice not only the one right above the wiper blade, but also the fender ones that point kind of left and potentially down ward. Some of the tufts did get stuck, but the one above the wiper wasn't. At the end of the video I do a walk around and you can (for the most part) tell which ones had gotten stuck. I've since put motorcycle mirrors on, made a new upper grill block, removed the air dam and removed the boat tail so the tufts that I test tomorrow might be slightly different. I will do it if it's not raining again.

You will want to mute the audio
I deleted the audio in the file, but for some reason it puts a loud noise at the beginning of the video. The rest is quiet.

https://www.youtube.com/watch?v=JN4a...hannel=M_a_t_t

[freebeard]

...when you can see the near horizontal tufts on my car.

What I find interesting is the top half of the door window. The tufts are streaming upward. No doubt they are feeding into a low pressure area.

[JulianEdgar]

Originally Posted by freebeard

What I find interesting is the top half of the door window. The tufts are streaming upward. No doubt they are feeding into a low pressure area.

Yes, very common.

[M_a_t_t]

Did a quick test. Didn't use as large of a fence as you did cd. I also made it "flush" with the side of the car rather than the fender. There is a speed discrepancy between the two runs. I only made the 2 runs as well. It's only 10 seconds long so you might want to adjust the playback speed. I forgot to get a picture of the piece I used while it was attached so it is kind of loosely in place.

https://www.youtube.com/watch?v=QlMv...hannel=M_a_t_t

I think the tufts look better without it. With it the side tufts are all pointing more vertical than the stock version. Stock they seem a little more steady as well, but that could just be the speed difference.

It is interesting that the windshield tufts seem unaffected by the fence. I would think the lower 2 (you can't see the top 3 in the stock version, but they closely match) would be pointing more up or more unsteady.

I was curious if I could attempt to ID the vortex (if present) from the A-pillar by using a small rod/stiff wire and a tuft to see what is happening a few inches off the surface. I couldn't find the coat hanger I was thinking of so I gave up on it for now. I might revisit that idea eventually though.

[oldtamiyaphile]

Originally Posted by Cd

Just out of curiosity, I added this side shield to see if i could direct airflow away from the mirror, as it spills around the windshield.
I even planned to take video, but everything flopped.
From the test, there was massive turbulence behind the mirror.
I also noticed the tufts just behind the mirror pointed straight up right as I began driving. This was evident at perhaps less than 10 mph.

In the photo, you can see how the piece has bowed outward. I installed it straight.

So what do you all think is happening ? Is air actually spilling over this shield and creating a massive vortex ?

I did some CFD that seemed to verify that even with a huge side shield, the air just spills right over the sides as if it's not even there.

Would it be worth it to do further testing on this ?

All modern cars have this feature to some extent. Even my 84 Celica has a fence along the side. My Renault has it's fences about an inch deep. There's probably a point where too deep adds drag.

[freebeard]

Originally Posted by JulianEdgar

Yes, very common.

Possibly a subject for a Youtube video? I don't comment there.

[JulianEdgar]

Originally Posted by freebeard

Possibly a subject for a Youtube video? I don't comment there.

I am not sure that there is any YouTube video content needed.

(1) All pressure measurements show low pressures over the roof in cars with attached flows (ie all that I have wool tufted in 35+ years).

(2) Nearly all wool tufting of the side of cars shows tufts being pulled upwards (to at least a degree) towards the roof.

My books have literally dozens of pics showing these features, and while I haven't looked this specifically in my YouTube videos, since most of the pics are from ny books, I am sure they show the same.

Now, as to the impact on lift and drag of this airflow direction, I have much less idea! It's something that - like many car aero things - is still within the research / testing regime of the amateur.

[freebeard]

Just trying to be helpful.

Originally Posted by yourself elsewhere

Julian Edgar
1 day ago
I am looking for suggestion for new video topics.

You could compare and contrast with the managed edge vortexia of the Cybertruck.