Vertical perturbation velocity is the vertical component of velocity at a particular point in a fluid flow that deviates from the freestream velocity. It quantifies how much the vertical velocity differs from the velocity of the fluid in the surrounding undisturbed flow.
- represents the vertical perturbation velocity at a specific point (in meters per second, m/s). It quantifies the deviation in vertical velocity from the freestream velocity at that specific point.
- is the freestream velocity (in meters per second, m/s), which is the velocity of the fluid approaching the point of interest.
- is the angle between the tangent to the surface at the point and the freestream direction (in radians).