If a fluid is incompressible, the divergence of this quantity is zero.
If a fluid is incompressible, the divergence of this quantity is zero. The sum of pressure head, elevation head, and this quantity's namesake head is constant. This quantity times diameter over viscosity equals the Reynolds number. This quantity times density times area is constant by the conservation of mass. This quantity is squared in (*) Bernoulli's equation, which shows that it goes up if pressure goes down. Volumetric flow rate equals this quantity times cross-sectional area. Often symbolized u, this quantity for a compressible fluid in a pipe cannot be greater than Mach 1. For 10 points, name this quantity measured in meters per second.
If a fluid is incompressible, the divergence of this quantity is zero.
fluid velocity [or speed; prompt on v; prompt on u]