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Airfoil lift and drag coefficients

The shape of a moving object determines its drag coefficient, Cd.

The drag coefficient combined with velocity and area of the
moving object determine the drag force.

  Fd = 1/2 * Cd * density * area * velocity^2

A few shapes and their respective drag coefficients are:




A symmetric NACA 0015 airfoil at zero degrees angle of attack


A symmetric NACA 0015 airfoil at 22 degrees angle of attack


Angle of attack shown in two degree increments


Wind tunnel measured data coefficient of lift and drag


Full set of wind tunnel data and full report
NACA-460 1933 78 airfoils 


Source code for computations and plots of airfoils
0015gl.c
0015grid.c
0015grid.out


Observe aircraft from past still flying:

video



More airflow over cylinder at high Reynolds number:

     inertial force   ρ u L        u L
RE = -------------- = --------- = ------
     viscous force      μ           ν

L is length m = characteristic length, chord for wing, diameter for circle
u is velocity m/s
ρ is density kg/m^3            water 1000 kg/m^3    air 1.275    kg/m^3
μ is dynamic viscosity kg/ms    water 0.001 kg/ms    air 2*10-5   kg/ms
ν is kinematic viscosity m^2/s  water 10^-6 m^2/s    air 1.9*10-5 m^2/s

density and viscosity change with temperature, pressure, fluid

Typical flow goes from laminar to turbulent as RE increases above 10

see flow result plots




temperature.shtml degree conversions


work in progress  still bugs:
cylinder_flow.c
cylinder_flow_c.out
cylinder_flow.java
cylinder_flow_java.out


wing_flow.java
wing_flow_java.out

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