disturbances are unavoidable on all but the simplest fluid systems. This means we must devise
ways to stabilize a flowstream’s velocity profile near the flow element in order to achieve accurate
measurements of flow rate. A very simple and effective way to stabilize a flow profile is to provide
adequate lengths of straight pipe ahead of (and behind) the flow element. Given enough time, even
the most chaotic flowstream will “settle down” to a symmetrical profile all on its own. The following
illustration shows the effect of a pipe elbow on a flowstream, and how the velocity profile returns to
a normal (symmetrical) form after traveling through a sufficient length of straight pipe
represent the full fluid flowstream