Will these strakes cause more drag ?

[Cd]

Yes, CFD software is crazy expensive.
And regarding Blender, that program is flat out amazing, but doesn't get any respect in the 3D community because it's free.
I have discussed the program with other 3D nerds, and felt like I was trying to SELL it it to them.
Despite being free, they don't want to even try it.

My current computer ( old ) won't run Blender .
I keep being amazed at what it can do.

[Cd]

So, is it possible to add an aerodynamic fence to direct airflow that is about to go turbulent on bodywork ?
I recall MetroMPG had some tufts on one his boat tail prototypes, in which the airflow was moving towards a low pressure area and going turbulent.
I think it was mentioned that fences would do nothing.

If they could be made to direct the airflow, would they also create drag in someway ?

Here is a crude example.
A would be airflow going turbulent.
B would be airflow channeled into a new path .
With red being the 'fences '.

[freebeard]

I fail at finding an example, but I've seen curved strakes on an underbody to sweep air sideways to behind the front wheels. Either it doesn't work or only works in the underbody plenum.

If they follow the predominant airflow, wouldn't they be vortex generators in crossflow conditions.?

If you can carve away the body, airflow can be focused into a jet. My brain needs a better example than the 1959 Chevy.

[Cd]

Originally Posted by freebeard

I fail at finding an example, but I've seen curved strakes on an underbody to sweep air sideways to behind the front wheels. Either it doesn't work or only works in the underbody plenum.

If they follow the predominant airflow, wouldn't they be vortex generators in crossflow conditions.?

If you can carve away the body, airflow can be focused into a jet. My brain needs a better example than the 1959 Chevy.

Yes. My thoughts too about acting as VG in crossflow conditions.
A 1959 Chevy ?
The Impala, correct ? I can't find it now, but I saw a tuft test of that car.
Also, the Alfa Romeo BAT 7 car comes to mind.

[freebeard]

'59s all had the 'cat eye' taillights. Here's a perhaps better example, the Pontiac Banshee. Not a tacked-on feature, it's almost an external duct.


https://www.pontiactransamforum.com/...t-car.571/full

I'm thinking of the groove that starts in the middle of the door that feeds into a cavity. I have no idea about the airflow around that feature.

[JulianEdgar]

Originally Posted by Cd

So, is it possible to add an aerodynamic fence to direct airflow that is about to go turbulent on bodywork ?
I recall MetroMPG had some tufts on one his boat tail prototypes, in which the airflow was moving towards a low pressure area and going turbulent.
I think it was mentioned that fences would do nothing.

If they could be made to direct the airflow, would they also create drag in someway ?

Here is a crude example.
A would be airflow going turbulent.
B would be airflow channeled into a new path .
With red being the 'fences '.

What do you mean by "going turbulent"? Do you mean "separating"?

[freebeard]

Isn't attached turbulent a valid category? If not, that's your real scandal here, not the default template.

[JulianEdgar]

Originally Posted by freebeard

Isn't attached turbulent a valid category? If not, that's your real scandal here, not the default template.

I doubt that Cd is talking about a transition from a laminar to turbulent boundary layer.

[freebeard]

Leaving that question to Cd...

If they could be made to direct the airflow, would they also create drag in someway ?

Examples I can think of vary in scale from small (dimples and VGs), to large (Cybertruck's longitudinal edges). Reattachment may net zero. It all seems to be about pressure drag. Is skin friction consistent or does it vary over the wetted area?

[Cd]

Sorry for being confusing.
What I'm wondering is if a 'fence' was directly in the path of air that is headed to a low pressure area and the fence is able to redirect and straighten it, would you still have some spillover that would trip over the fence and go turbulent.
And Julian, yes, I meant air separating and then going turbulent.
BTW, I recently came across your A pillar " side curtain " video.
This is just what I was after, since I am trying to change the direction of tufts on the sude of the car.
I'm already making plans to create some.

So I'd like to ask what is happening around the sides of our cars' A pillar windows as the tufts point towards the roof, rather than straight back.
I know this is due to the tufts being pulled to where there is a change in air pressure ( low pressure, correct ? )
But if the tufts are pointed straight up to the roof, but are steady and not fluttering, this seems to show that the airflow is attached - but since they are pointed away from the rest of the flow, is this a sign that this is a problem area that could be corrected ?