Visualizing Air Flow: here's an idea

[CigaR007]

1. Have you ever played with spinning fiery steel wool as a kid ? I know I have.

2. Have you ever experimented with long exposure photography ? I know I have.

3. Are you looking for a way to visualize air flow on your vehicle, for an in-depth understanding of its interactions with said-object ? I know I am.

How about combining all of those ?

Imagine installing a spinning device on the lower front bumper, near the stagnation point, and lighting up some steel wool. The resulting fiery fine steel particles would cover the entire frontal area of the vehicle. The incoming air flow would then re-align those particles from a sideways momentum to a longitudinal momentum, thus creating lines of "visible" airflow by using long-exposure photography.

The same could be done at the rear bumper in order to expose the wake turbulence.

1. The camera would be setup on a sturdy tripod to get a side view of the vehicle, preferably at a wide angle.

The spinning device could be cordless drill.


Been thinking about this for a while. Wondering if it might work...

Thoughts ?

[freebeard]

Back when we were talking about smoke trails, aerohead told the story about when he lit off a green smoke grenade on his surf board and an attack helicopter came sniffing around.

My suggestion at the time was something like a windshield wiper that would sweep the entire frontal area with a nozzle that would travel along it's length.

Substitute Dragon's Breath rounds.

https://en.wikipedia.org › wiki › Dragon's_breath_(ammunition)
Dragon's breath (ammunition) - Wikipedia
Dragon's breath is a special type of incendiary-effect round for 12 gauge (18.5 mm) shotguns. Dragon's breath consists primarily of magnesium pellets/shards. When the round is fired, sparks and flames can shoot out to about 100 feet (30 meters), although, some sources claim it extends to 300 feet (91 meters). [1]

[Cd]

So if I undersand, this produces smoke, correct ?
Or is more like sparks of some sort that emanate from it ?

I like that idea of time exposure photography !

[CigaR007]

Originally Posted by Cd

So if I undersand, this produces smoke, correct ?
Or is more like sparks of some sort that emanate from it ?

I like that idea of time exposure photography !

No smoke per se as a consequence. Just trails of light from the burning particles.



It would be a like a CFD, but in real life.

[Gasoline Fumes]

But what will the hot sparks do to the surface of the car?

[CigaR007]

Originally Posted by Gasoline Fumes

But what will the hot sparks do to the surface of the car?

That's a valid concern. I don't know.

Odds are it would probably cause some damage.

Tests would need to be undertaken on a variety of surfaces, prior to attempting it on an actual vehicle.

[Piotrsko]

Originally Posted by CigaR007

That's a valid concern. I don't know.

Odds are it would probably cause some damage.

Tests would need to be undertaken on a variety of surfaces, prior to attempting it on an actual vehicle.

Take a grinder, a chunk of random steel and grind on it near some sort of paint finish while producing lots of sparks. You'll find the paint finish gets ruined rather abruptly and quickly by the sparks as along with anything that has an elastic temperature less than the melting point of steel.

[CigaR007]

I wonder if most of the particles would just flow downstream with the laminar flow, without much contact with the surface paint.

Side mirrors and the front bumper are another story, given that they would be obvious obstacles where the heated particles would do the most damage.

[freebeard]

A picture I've always wanted to find was in an ad in Hot VWs in the 70s or 80s. VW Beetles racing in the rain with rooster-tails of water off the top of the windshields.

Things heavier than air don't act like air.

[Cd]

Originally Posted by freebeard

A picture I've always wanted to find was in an ad in Hot VWs in the 70s or 80s. VW Beetles racing in the rain with rooster-tails of water off the top of the windshields.

Things heavier than air don't act like air.

This is a still from a video I uploaded. My camera frame rate must be different than my vision, because I can clearly see the upward spiral of the rain spray behind the cab on semis, but my camera doesn't show it.
BTW, I found out that youtube automatically makes these videos " Youtube Shorts ", so I'm not sure if you all can watch the video in slow motion and zoom in.
Anyway, here is a still frame from the few seconds of video I posted. I definately shows how that indeed rain spray is not a good indicator of drag. Just look at how some small cars kick up more spray than trucks with open trailers !NOTE - I really zoomed in and cropped these images :