Unsteady Flow in a Reservoir‐Conduit System

The one‐dimensional method of solution computes successfully the instantaneous average displacement, velocity, and acceleration of fluid in the pipe and the water depth in the reservoir when a valve at the end of the conduit is suddenly opened. Measurements of the instantaneous average fluid displacement in the pipe for different values of B/D (reservoir diameter to pipe diameter) agree very well with the computed values. For a specific inlet geometry and a given value of the ratio of pipe length to pipe diameter, the lumped inertial parameter decreases as B/D increases and reaches a minimum value as B/D becomes infinity. The neglect of the inertia of fluid in the reservoir in computing the unsteady flow characteristics is justifiable if B/D is larger than 90 and L/D much larger than 0.47.