(as a pilot) Your point made in the diagram in Figure 7 about tangent of the shear layer friction always pointing outside the curve, is that how venturis and bernoulli's principle work?
I'll be looking through your posts to see if there's an explanation for vortex generators too, which always seem like magic to me. Cool posts!
I don't think Figure 7 really relates to Venturi/Bernoulli principles. Those models are more used for idealized flow (steady, no energy loss), they don't really apply for flow in wakes because it's transient/turbulent & energy *isn't* conserved -- the flow inside of the wake is both low speed and low pressure (meaning less total energy than the free stream flow, which has high speed and neutral pressure) so you can't really use Bernoulli's principle to compare it to flow elsewhere.
I haven't thought about vortex generators much in a long time, but I think you could tie them into some of the ideas in this series of posts. One of the points I make is that there needs to be some way for air to get *into* the wake, to lessen the strength of the vacuum. Using some sort of obstacle to create small vortexes is one way to potentially do that.
At least, that's how I think of vortex generators for cars/trucks. On planes they might have a different function, e.g. breaking up what could be one large vortex (like the "C-pillar vortex" in Fig 13 of the "Big wakes and small wakes" post) into smaller vortexes that are better for the flight characteristics you're trying to achieve.
(as a pilot) Your point made in the diagram in Figure 7 about tangent of the shear layer friction always pointing outside the curve, is that how venturis and bernoulli's principle work?
I'll be looking through your posts to see if there's an explanation for vortex generators too, which always seem like magic to me. Cool posts!
Thank you!
I don't think Figure 7 really relates to Venturi/Bernoulli principles. Those models are more used for idealized flow (steady, no energy loss), they don't really apply for flow in wakes because it's transient/turbulent & energy *isn't* conserved -- the flow inside of the wake is both low speed and low pressure (meaning less total energy than the free stream flow, which has high speed and neutral pressure) so you can't really use Bernoulli's principle to compare it to flow elsewhere.
I haven't thought about vortex generators much in a long time, but I think you could tie them into some of the ideas in this series of posts. One of the points I make is that there needs to be some way for air to get *into* the wake, to lessen the strength of the vacuum. Using some sort of obstacle to create small vortexes is one way to potentially do that.
At least, that's how I think of vortex generators for cars/trucks. On planes they might have a different function, e.g. breaking up what could be one large vortex (like the "C-pillar vortex" in Fig 13 of the "Big wakes and small wakes" post) into smaller vortexes that are better for the flight characteristics you're trying to achieve.