Hmmm... sealing panel gaps... materials?

[aerohead]

Originally Posted by Phase

Can’t panel gaps also act as mini vortex generators and accelerate the flow?

Nope!
* From Hucho, Janssen, and Emmelmann, SAE Paper # 760185, Page-15, Figure 27, we're instructed that a 'gap' can only trigger TBL separation, and only on a 'roof.'
* Tripping the flow 'ahead' of an 'adverse-positive-pressure-gradient-inducing roofline, prohibits the flow separation-induced downwash drag and lift which would otherwise develop, had the flow not been intentionally separated.
* With the 1st-gen Golf-Rabbit, simply taping the rear hatch gap on the roof, caused the drag to degrade from Cd 0.42, to Cd 0.48 ( 14% ), along with 28% increased rear lift, due to the counterrotating vortex pair, low pressure downwash vector 'above' the backlight, and small, low-pressure wake.
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* Any form of VG would have to 'protrude' into the TBL, rather than reside within some body recess.

[Phase]

Originally Posted by aerohead

Nope!
* From Hucho, Janssen, and Emmelmann, SAE Paper # 760185, Page-15, Figure 27, we're instructed that a 'gap' can only trigger TBL separation, and only on a 'roof.'
* Tripping the flow 'ahead' of an 'adverse-positive-pressure-gradient-inducing roofline, prohibits the flow separation-induced downwash drag and lift which would otherwise develop, had the flow not been intentionally separated.
* With the 1st-gen Golf-Rabbit, simply taping the rear hatch gap on the roof, caused the drag to degrade from Cd 0.42, to Cd 0.48 ( 14% ), along with 28% increased rear lift, due to the counterrotating vortex pair, low pressure downwash vector 'above' the backlight, and small, low-pressure wake.
--------------------------------------------------------------------------------------
* Any form of VG would have to 'protrude' into the TBL, rather than reside within some body recess.

Taping over the gap increase drag? I’m confused

[Slipstream88]

That is a good consideration. My current focus in on the front of the vehicle where i'm hoping to maintain least amount of approach drag. Could be a low to zero benefit, but I prefer to test and verify for myself and move on.

Thanks for the feed back

[aerohead]

Originally Posted by Phase

Taping over the gap increase drag? I’m confused

1) On the Golf-I, the roofline was not 'aerodynamic', as designed by ItalDesign, and prone to Cd 0.48.
2) Hucho et al. investigated 'BandAids' for the Beetle's replacement, in their new wind tunnel.
3) They achieved Cd 0.34 using a 'template' roofline, but that was shot down in committee because it didn't 'look' like the ItalDesign car ( which is a legal requirement between a contracting manufacturer and designer ).
4) 'Taping' the rear hatch roof gap was one of the things they tried in the pursuit of a lower Cd, but discovered that the gap was producing a lower drag 'squareback' wake, compared to a higher drag pseudo-Jaray wake of 'small', but low-pressure/ high drag/ high lift ( exactly as VW-Porsche found on the 1972 911 Carrera RS 2.7, 'Pete' Brock with the Shelby Cobra Daytona Coupe, and Bob Lutz with the Dodge Viper Coupe ).
5) So, by leaving the gap open, they were allowed to get from Cd 0.48, down to Cd 0.43, for the 'final' production shape.

[Tahoe_Hybrid]

Originally Posted by Sean T.

So... I know the traditional material for random aero testing is usually painters tape, and I love the color against the color of my paint, but it simply isn't practical... It gets wet and then is tremendously difficult to remove...

What about electrical tape? would the thickness of electrical tape defeat the purpose of sealing the gaps? and does anybody know how long electrical tape will last on a car?

or if anybody else has a good idea? I really don't want to spend much and I don't want it to be messy, so no silicone or other goop.

i would not use electrical tape, duct tape etc it gets gooey when it gets heated up... it might rip off the paint as well i suggest a rubber gasket to fit between the gaps

[freebeard]

i suggest a rubber gasket to fit between the gaps

Pickup trucks need pool noodles.