A method and apparatus useful to determine characteristics of fluid flow, such as fluid holdup and flow velocity. The apparatus comprises a flow tube, a permanent magnet, a first set of coils, and a second set of coils. The first set of coils creates a radio frequency magnetic field within the flow tube...http://www.google.de/patents/US7372263?utm_source=gb-gplus-sharePatent US7372263 - Apparatus and method for measuring cased hole fluid flow with NMR
