1. n. []

In the context of spinner flowmeters, the apparent fluid speed measured by the spinner as the tool is moved up and down the well. The effective velocity is the algebraic sum of the actual fluid velocity and the velocity with which the flowmeter is moving, as determined by cable speed. If the tool moves against the flow, the two velocities are added; if moved with the flow, they are subtracted.

See related terms: flow profile,  multipass method,  single-pass method,  spinner flowmeter,  spinner reversal,  threshold velocity,  two-pass method,  velocity correction factor