1. n. [Well Completions, Production Logging]

A multiphase flow regime in near-vertical pipes in which large, irregular slugs of gas move up the center of the pipe, usually carrying droplets of oil or water with them. Most of the remaining oil or water flows up along the pipe walls. The flow is relatively chaotic, producing a frothy mixture. Unlike slug flow, neither phase is continuous. The gas slugs are relatively unstable, and take on large, elongated shapes. Also known as transition flow, this flow is an intermediate flow condition between slug flow and mist flow and occurs at relatively high gas velocity. As the gas velocity increases, it changes into annular flow.

Synonyms: transition flow

See: annular flow,  bubble flow,  flow regime,  flow structure,  mist flow,  multiphase fluid flow,  slug,  slug flow

2. n. [Production Logging]

A multiphase flow regime in near-vertical pipes in which large, irregular slugs of gas move up the center of the pipe, usually carrying droplets of oil or water with them. Most of the remaining oil or water flows up along the pipe walls. Unlike slug flow, neither phase is continuous. The gas slugs are relatively unstable, and take on large, elongated shapes. Churn flow occurs at relatively high gas velocity and is similar to froth flow. As the gas velocity increases, it changes into annular flow.

See: bubble flow,  flow structure,  mist flow