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fractal wings: self-similar dimpling of aerodynamic...

Author Message
Roger Bagula...
Posted: Thu Aug 13, 2009 3:34 am
Guest
I have been looking at aerodynamic surfaces.
Are you aware that dimpling on golf balls was developed to reduce
their drag?
http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml
Roughness on a sphere can also reduce fluid drag by
reducing surface effects.

My first idea was that you could make flat surfaces with one side
raised slightly in a self-similar dimpling to make a new kind of
fractal wing. Dimpling on wings is actually not very new.
The idea of fractal roughness in self-similar terms
to decrease friction and increase lift seems to be new.
Something like a Fresnel lens in fractal terms.
They have Photoshop brushes called "fractal wings":
http://zatstyles.blogspot.com/2009/04/fractal-wings-brushe-by-flashtuchka.html
but that has noting to do with vortex effects by self-similar
fractals.
I found this paper online:
http://www.tc.gc.ca/innovation/tdc/projects/air/f/9117.htm
that seems to confirm that some relationship might exist.

At the least it is an idea worth exploring.
Respectfully, Roger L. Bagula
11759Waterhill Road, Lakeside,Ca 92040-2905,tel: 619-5610814 :http://
www.geocities.com/rlbagulatftn/Index.html
alternative email: rlbagula at (no spam) sbcglobal.ne
 
Roger Bagula...
Posted: Fri Aug 14, 2009 5:06 am
Guest
Off topic post to show that wings can be modeled in software
at hand:
Whitcomb supercritical airfoil wings in a Mathematica model:
This idea was more about could
a model be made in Mathematica of
the supercritical airfoil using the data on the web that I downloaded.
Model like these were inspired by the Mathematica pages
of Mark McClure.
I've made a number of these flights of imagination
in Mathematica.


Pictures are at:
http://www.flickr.com/photos/fractalmusic/3819251048/
http://www.flickr.com/photos/fractalmusic/3819250762/
Respectfully, Roger L. Bagula
11759Waterhill Road, Lakeside,Ca 92040-2905,tel: 619-5610814 :http://
www.geocities.com/rlbagulatftn/Index.html
alternative email: rlbagula at (no spam) sbcglobal.net

Mathematica:
Clear[a, b, w, f, g, g1, g2, g3, g4, x, y, z, p]
(* http : // www.aerospaceweb.org/question/airfoils/q0127b.shtml*)
(*NASA/Langley Whitcomb integral supercritical airfoil*)
(*WHITCOMB INTEGRAL SUPERCRITICAL AIRFOIL*)
(*top*)
a = {{0.0 , 0.0},

{.0075 , .0176},

{.0125, .0215},

{.0250 , .0276},

{.0375 , .0316},

{.0500 , .0347},

{.0750 , .0394},

{.1000 , .0428},

{.1250 , .0455},

{.1500 , .0476},

{.1750, .0493},

{.2000 , .0507},

{.2500, .0528},

{.3000, .0540},

{.3500 , .0547},

{.4000 , .0550},

{.4500, .0548},

{.5000, .0543},

{.5500, .0533},

{.5750, .0527},

{.6000 , .0519},

{.6250 , .0511},

{.6500 , .0501},

{.6750 , .0489},

{.7000, .0476},

{.7250 , .0460},

{.7500 , .0442},

{.7750 , .0422},

{.8000 , .0398},

{.8250 , .0370},

{.8500 , .0337},

{.8750 , .0300},

{.9000 , .0255},

{.9250 , .0204},

{.9500, .0144},

{.9750 , .0074},

{1.0000, .0008}, {1.0075, 0}}
Length[a]
f[x_] = Fit[a, Table[x^n, {n, 0, Length[a]}], x]
g3 = Plot[f[x], {x, 0, 1}, AspectRatio -> Automatic, Axes -> False]
g1 = ListPlot[a, AspectRatio -> Automatic, Axes -> False, PlotJoined -
[quote:7c2a55bbc6]True]
(*bottom*)[/quote:7c2a55bbc6]
b = {{0.0 , 0.0},

{.0075, -.0176},

{.0125, -.0216},

{.0250, -.0281},

{.0375, -.0324},

{.0500, -.0358},

{.0750, -.0408},

{.1000, -.0444},

{.1250, -.0472},

{.1500, -.0493},

{.1750, -.0510},

{.2000, -.0522},

{.2500, -.0540},

{.3000, -.0548},

{.3500, -.0549},

{.4000, -.0541},

{.4500, -.0524},

{.5000, -.0497},

{.5500, -.0455},

{.5750, -.0426},

{.6000, -.0389},

{.6250, -.0342},

{.6500, -.0282},

{.6750, -.0215},

{.7000, -.0149},

{.7250, -.0090},

{.7500, -.0036},

{.7750, .0012},

{.8000 , .0053},

{.8250, .0088},

{.8500 , .0114},

{.8750, .0132},

{.9000, .0138},

{.9250, .0131},

{.9500, .0106},

{.9750, .0060},

{1.0000, -.0013}, {1.0075, 0}}

g2 = ListPlot[b, AspectRatio -> Automatic, Axes -> False, PlotJoined -
[quote:7c2a55bbc6]True]
Show[{g1, g2}][/quote:7c2a55bbc6]
Length[b]
g[x_] = Fit[b, Table[x^n, {n, 0, Length[a]}], x]
g4 = Plot[g[x], {x, 0, 1}, AspectRatio -> Automatic, Axes -> False]
Show[{g3, g4}]
w[x_] = {{x, f[x]}, {x, g[x]}}
Clear[x]
gt1 = ParametricPlot3D[{p, 4.5 + 5*(x + p/10), 5*f[x], {EdgeForm[]}},
{x,
0, 1}, {p, 0, 6}, Boxed -> False, Axes -> False, PlotPoints -> 40]
gb1 = ParametricPlot3D[{p, 4.5 +
5*(x + p/10), 5*g[x], {EdgeForm[]}}, {x, 0, 1}, {
p, 0, 6}, Boxed -> False, Axes -> False, PlotPoints -> 40]
gt2 = ParametricPlot3D[{-p,
4.5 + 5*(x + p/10), 5*f[x], {EdgeForm[]}}, {x, 0, 1}, {
p, 0, 6}, Boxed -> False, Axes -> False, PlotPoints -> 40]
gb2 = ParametricPlot3D[{-p, 4.5 + 5*(x + p/10), 5*g[x], {
EdgeForm[]}}, {x, 0, 1}, {p, 0, 6}, Boxed ->
False, Axes -> False, PlotPoints -> 40]
Show[{gt1, gb1, gt2, gb2}, ViewPoint -> {-0.091, -2.263, 2.514}]
gt1t = ParametricPlot3D[{p/2, 17 + 5*(x + p/10)/2, 1 + 5*
f[x]/2, {EdgeForm[]}}, {x, 0, 1}, {p,
0, 6}, Boxed -> False, Axes -> False, PlotPoints -> 40]
gb1t = ParametricPlot3D[{p/2, 17 + 5*(x + p/10)/
2, 1 + 5*g[x]/2, {EdgeForm[]}}, {x, 0, 1}, {p, 0, 6}, Boxed -> False,
Axes -> False, PlotPoints -> 40]
gt2t = ParametricPlot3D[{-p/2, 17 + 5*(x + p/10)/2, 1 + 5*f[x]/
2, {EdgeForm[]}}, {x, 0,
1}, {p, 0, 6}, Boxed -> False, Axes -> False, PlotPoints -> 40]
gb2t = ParametricPlot3D[{-p/2, 17 + 5*(x + p/
10)/2, 1 + 5*g[x]/2, {EdgeForm[]}}, {x, 0, 1}, {p, 0, 6},
Boxed -> False, Axes -> False, PlotPoints -> 40]
Show[{gt1t, gb1t, gt2t, gb2t}, ViewPoint -> {-0.091, -2.263, 2.514}]
(*Wasp waist airfoil body model*)
Clear[g2]
Clear[f, g, h, k, j, i, e, t, x, y, z]
(*Bernoulii pressure equation for constant pressure : p0 =
p - pInfinity = (1/2)*rho*UInfinity*(1 - U^2/UInfinity^2)
such that radius*
Sin[r] = (1/2)*rho*UInfinity : (1 - Cos[r]^2) = (1 - \
U^2/UInfinity^2)*)

x = Cos[t]*(1 - Cos[r]^2)*Sin[r]*(Cos[-Pi + 2.5*Abs[r]])/2;
y = Sin[t]*(1 - Cos[r]^2)*Sin[r]*(Cos[-Pi + 2.5*Abs[r]])/2;
z = Cosh[r];


g2 = ParametricPlot3D[{3*x, 3*(-1 + z), 3*y, {
EdgeForm[]}}, {t, -Pi/2, 3*Pi/2}, {r, 0, Pi - 0.4},
ViewPoint -> {2.8, -1.9, 0.1},
PlotPoints -> {30, 30},
Boxed -> False,
Axes -> False,

LightSources ->
{{{0.7071, 0, 0.7071}, RGBColor[0.9481, 0, 0]},
{{0.5773, 0.5773, 0.5773}, RGBColor[0, 0.8888, 0]},
{{0, 0.7071, 0.7071}, RGBColor[0, 0, 1]}}
];
(*Tail Fin model*)
Clear[x, y, z, n, t, r, p]
x0 = Cos[-Pi + 2*t]*Cos[p]/2;
y0 = Exp[2] - Exp[Sin[-(-Pi + 2*t)] + 1]*Cos[p];
z0 = 3*Pi*Sin[p];
g4 = ParametricPlot3D[{x0/4, y0/2 + 17, z0/2, {EdgeForm[]}}, {t, -Pi,
Pi}, {p, 0, Pi/2}, Axes -> False, Boxed -> False];
(*Two views*)
ga = Show[{gt1, gb1, gt2, gb2, gt1t, gb1t, gt2t, gb2t, g4,
g2}, PlotRange -> All]
Show[ga, ViewPoint -> {-1.215, -1.045, 2.980}]
Export["supercriticalwasp.DXF" , ga, "DXF"]
 
Roger Bagula...
Posted: Fri Aug 14, 2009 5:39 am
Guest
A profile that might be possible for a wing roughness model is this
tri-farey function
with limited height:
http://www.flickr.com/photos/fractalmusic/3820841066/
Tri-Farey Function working:
f[x_] := (9*x/(8 - 18*x)) /; 0 <= x ? 2/9
f[x_] := 9*x/4 /; 2/9 < x ? 4/9
f[x_] := ((4/5)(1 - x)/(x)) /; 4/9 < x <= 1
:two curved parts and one straight/linear.

I call the Mandelbrot cartoon function or Besicovitch - Ursell
function
as biscuit function.
I attached the fractal that results which is not symmetrical.
This resulting curve is more like the kind of responses seen in
nature.


In continuum mechanics they call that kind of response curve a
Voigt solid/ model which corresponds to a force model of how a solid
responds to force.
F=a*x+b*dx/dt

The tri-Farey function, then is more like quadratic
nature force system.
Respectfully, Roger L. Bagula
11759Waterhill Road, Lakeside,Ca 92040-2905,tel: 619-5610814 :http://
www.geocities.com/rlbagulatftn/Index.html
alternative email: rlbagula at (no spam) sbcglobal.net
 
Roger Bagula...
Posted: Fri Aug 14, 2009 12:52 pm
Guest
Models from Mathematica of aircraft with fractal
wings ( fractal function as cylinder on the top of the wings);

http://www.flickr.com/photos/fractalmusic/3821840478/
http://www.flickr.com/photos/fractalmusic/3821033855/


Getting the wings into my ray trace program was the hard part.
The DXF files came out 31mb for 120 points on wing;
5.8 for 50 points
and finally which worked 3.3 for 38 points.
The Mathematica picture is the 120 point wings...
"Real' wings of this type should probably have 1000 points at least.
 
 
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