Airfoil start-stop motion (linear) with 20,000 tracers

Same as the previous video with the same name but now with 20,000 passive tracer particles to reveal what's going on around the aerofoil and wake. The important thing to observe here is how the bulk of the fluid in the wake region is moving slowly downwards. This nicely illustrates the wake-induced downwash which is responsible for reducing the effective angle of attack of the wing and tilting the resultant force vector rearwards a little giving the induced-drag (an inviscid drag).

Coming soon:

Flapping motion to give static lift / thrust (i.e. without uniform forward motion already in place). This is what flapping wings are really about.

Upgrade to 3D flow ;-D! w00t! This is actually the ultimate purpose of all of this. I want to simulate a spinning propeller (with and without duct) to test my propreitary design algorithm I developed last year. Then couple the propeller flow solver to an optimisation algorithm that can change the surface shape.... and see what comes out ;-)))

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  Education

[Pavel Kurchanov]

What is the program ??????????



[khyar]

Hi, it is my own Visual Basic code I developed last year. This 2D code served as a stepping-stone for the 3D version that came after it. Its main purpose at the time was to simulate the flow around propeller and wind turbine blades.

[HathaYodel]

What relationship -- if any -- is there between this and your 'curlicue fractals'?

[khyar]

In terms of the mathematics of the problem - none. However in terms of the visual features of rolled up spiralling structures there appears to be some similarity, and this actually got me to look at the curlicue fractal family in the first place. On the one hand you have a very complex set of equations producing the fluid flow above, and on the other hand a very simple set to make the Curlicue fractal....

[khyar]

.... The irony is that the Curlicue fractal is infinitely complex yet comes from far simpler equations. This is a hallmark of our Universe - complexity arising out of simple rules applied recursively to multiple entities. So yes, an interesting observation that some of the Curlicue fractals resemble the wake pattern of this aerofoil motion....

[Jesh Kundem]

Did you do the same thing for flapping wings ?