Who uses vortex generators?

[ConnClark]

Originally Posted by ryannoe

Exactly.

What CFD software are you using?

-Ryan

OpenFoam-2.1.1

[RedDevil]

I'm done with argueing, I know what I know and I will put that in practice as soon as I'm done and happy with the easier mods.
Hard data however might be helpful, in any shape or form.

PS (edit): Please don't take this as a personal attack. A devil with clogs is bound to hurt a few toes by nature, I fear.

[ryannoe]

RedDevil - Hope that isn't aimed at me. I'm only here to help. Good luck!

-Ryan

[kennybobby]

i have some more questions, but i saw a late model toyota camry up close today at rideout and martin road--the headlights have some sort of VG molded into the top outer corner that even has some sort of zigzag-stair-step pattern on the leading edge. Thanks to this thread i had a clue...lol

Ryan,
When you say that your rear window has separated flow, do you mean there is a laminar flow boundary layer close to the glass and there is also a flow stream higher up above the surface of the glass that has detached from the upper edge of the boundary layer? And this separated flow layer makes the rear spoiler ineffective? Is the separated layer (always) turbulent or possibly laminar/free-stream in character? How far above the glass do you think this separated flow begins (at the top edge of a very thick boundary layer)? Maybe some redundancy in the questions here, so feel free to summarize it if you can explain all this flow stuff to some of us aero novi...

[ChazInMT]

I only state things that I've heard from others who know way more than me. Think that you have laminar flow over your car body all you want, facts are still that the flow is not laminar, unless you're driving a wing shaped car in the middle of nowhere with no other cars around.

I write this not to argue, but to make sure your fallacies are not taken as fact by others who look in on this discussion thread.

Don't believe me. But you may wanna listen to this guy.

I know yer gonna beat me to death with #7, read #13 before you get too carried away.

[RedDevil]

Originally Posted by ryannoe

RedDevil - Hope that isn't aimed at me. I'm only here to help. Good luck!

-Ryan

Sorry guys, it's not aimed at anyone.
Posted late and without much consideration for the fact that what sounds straight in Dutch can sound blunt if literally translated into another language. Dutch conversation is usually very open and direct, even challenging without really meaning to. I apologize.

I just wanted to state that I'll go ahead with my plan, but will not close myself for factitional info that may point me in a different direction.
But as we don't agree on some matters let's not repeat ourselves.

[ryannoe]

Originally Posted by kennybobby

i have some more questions, but i saw a late model toyota camry up close today at rideout and martin road--the headlights have some sort of VG molded into the top outer corner that even has some sort of zigzag-stair-step pattern on the leading edge. Thanks to this thread i had a clue...lol

Ryan,
When you say that your rear window has separated flow, do you mean there is a laminar flow boundary layer close to the glass and there is also a flow stream higher up above the surface of the glass that has detached from the upper edge of the boundary layer? And this separated flow layer makes the rear spoiler ineffective? Is the separated layer (always) turbulent or possibly laminar/free-stream in character? How far above the glass do you think this separated flow begins (at the top edge of a very thick boundary layer)? Maybe some redundancy in the questions here, so feel free to summarize it if you can explain all this flow stuff to some of us aero novi...

KennyBobby - I didn't realize how close you are. We should grab lunch... I'm on the airfield off Hale Rd (the first light as you come in Gate 9 going south on Rideout).

As for the questions, I'll just go down through the para.

Q1: When you say that your rear window has separated flow, do you mean there is a laminar flow boundary layer close to the glass and there is also a flow stream higher up above the surface of the glass that has detached from the upper edge of the boundary layer?
A1: No, this isn't possible to my knowledge. -Boundary layers are a result of the shear stress of the object on the air. It starts smoothly, trips to turbulence, and then eventually if the object has adverse curvature (curving away from the flow), the flow detaches and there is a stagnation point... if the detached flow is large enough and an adverse pressure gradient is present, you'll have reversed flow.

Q2: And this separated flow layer makes the rear spoiler ineffective?
A2: Yes, the spoiler requires air to move across it to produce it's downforce. If the flow across the spoiler is moving very slowly as a result of being in the detached flow (the stagnant or reverse flow area), no air is really pushing across it rendering it ineffective. It doesn't produce drag! But it doesn't produce downforce...

Q3: Is the separated layer (always) turbulent or possibly laminar/free-stream in character?
A3: Separated flow is flow that is no longer part of the freestream. This is a hard question to answer because stagnant air has neither turbulent nor laminar characteristics. The separated "area" can changes characteristics based on your velocity. It can start out as just a stagnant spot with very small eddies and as you go faster, can result in the oscillating vortices that you experience behind the big rigs on the interstate.

Q4: How far above the glass do you think this separated flow begins (at the top edge of a very thick boundary layer)?
A4: On my Prius, it looks to separate just behind the antenna. It appears the separation caused by the antenna acts like a catalyst to break up the flow further down the back glass.

-Ryan