A wing moving in fluids experiences a fluid force, which follows the conventions found in aerodynamics. The force component normal to the direction of the far field flow relative to the wing is referred to as lift ("L"), and the force component in the opposite direction of the flow is drag ("D"). At the Reynolds numbers considered here, an appropriate force unit is 1/2(ρU2S), where ρ is the density of the fluid, S the wing area, and "U" the wing speed. The dimensionless forces are called lift ("CL") and drag ("CD") coefficients, that is: