nice video, I just want to ask on flow over plate, what is the meaning dp/dx=0??,. if dp/dx=0, then in flow over plate, separation will not occur even we extend the length of plate ??
Dear Fajar, dP/dX = 0 relates to the overall flow, where the velocity is constant. Because of the bernoulli equation, this means the pressure is also constant. However, you are right, this is a simple approximation. Because of friction (which indeed increases as the length of the plate increases) the pressure can indeed vary as you travel along the plate. And, as the boundary layer grows thicker, you can have a transition from laminar to turbulent at a certain point. This video is also quite interesting ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5zLCofDSt_Q.html
In the 2:05, you mentioned that " If the pressure gradient in the horizontal plane is positive or zero, velocity gradient in vertical is positive." but it looks in the image and from the knowledge it must be negative pressure gradient right?
Hi David, we haven't had that question before :) Surface friction goes up with velocity, viscosity, surface area, surface roughness ... so those would be the parameters to work on. Keep in mind that you may trigger separation, creating a turbulent flow which has different friction properties as well.
Dear Josué, I don't think I fully understand the question - if by streamwise direction you mean the flow lines, the pressure changes as the air slows down & speeds up (linked to the Bernoulli effect). What do you mean with the streamwise direction?
It's indeed fairly theoretical, but perhaps you can experiment in real life with some tufts on a car? We had fun doing so on this VW Beetle: airshaper.com/videos/diy-aerodynamics-2-vortex-generators/MC6woj6tsQY
There is definitely a growing interest for "shape morphing" objects that can change shape in function of the aerodynamic goals. Or flexible materials, that deform under aerodynamic loads.
@@gtnb8746 I don't feel I owe the community this information - the content needs to be good and speak for itself. Nevertheless: Education - Masters in mechanical engineering (with just the basics of fluid mechanics) - Post-grad degree in product design - Degree in car mechanics (4 years of after-work evening schooling) - Self-study on deeper CFD principles Experience - 10 years of experience in OpenFOAM (CFD environment) - 7 years as project manager for FEA/CFD simulations & wind tunnel testing at engineering agency (prior to founding AirShaper) - 8 years of experience prototyping & developing the online simulation platform AirShaper (I'm the founder / CEO) - Patented aerodynamics concept (see airshaper.com/cases/aquilo-patented-aerodynamic-concept-car) - Occasional teaching on aerodynamics at universities / private companies - ...
@@synergy6294 That is true, but flow separation is about the relative velocity between the surface & the surrounding flow. So whether it is the wind moving across a static element, or an element moving through static air, the same principles apply.
@@AirShaper actually not You can not make a parked plane takeoff no matter how much air the propellers flow over the wings on the tarmac. It will fly only when it moves :) and achieves v1... ok ? Study the book on new zone theory of lift.
