Forces on bodies in flow; drag coefficient and lift coefficient quantify them.
Drag F_D=½ρV²AC_D, lift F_L=½ρV²AC_L. Drag components: friction and pressure (form) drag. Streamlining reduces C_D. Lift for aerofoils depends on angle of attack and rises until stall. Terminal velocity occurs when drag equals weight.
A parachutist reaches terminal speed when drag balances weight.
Drag and lift determine the forces on vehicles, buildings and aircraft, so drag and lift coefficients are used to size them.
Forces on bodies in flow; drag coefficient and lift coefficient quantify them.
Drag and lift determine the forces on vehicles, buildings and aircraft, so drag and lift coefficients are used to size them.
A dimensionless number that gives drag as a fraction of dynamic pressure times frontal area, and it depends on shape and Reynolds number.
Drag force rises with the square of speed, so doubling speed increases drag fourfold for the same shape.
Typical applications include estimating the drag force on a car at highway speed, calculating the lift needed for a light aircraft to take off and comparing the drag of a bluff body and a streamlined shape.
Study "Boundary layer" first (topic 70 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
C_D sphere ≈0.47. Car C_D≈0.3. Induced drag.
A parachutist reaches terminal speed when drag balances weight.
The next topic is "Flow separation", which builds directly on this one.
It is classed as Intermediate in Thermodynamics & Fluids (topic 71 of 105). It is an intermediate topic. Work through the beginner topics in Thermodynamics & Fluids first.
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