Water analogy

摘要

Pump A in Figure 1 forces water at constant pressure, P_1, around a closed loop. As long as Valve B remains open or at least partially open, the water flowing in the pipe attains steady velocity, V_1. The pump pressure; the viscosity of water; and the effective fluid-flow resistance of the pipes, valves, and elbows used in the circuit determine this velocity. The plumbing circuit is analogous to a simple electrical circuit comprising a battery, a resistor, and a connection from the opposite end of the resistor back to the battery, representing the tank.