ABSTRACT
Multi-phase flow concerns the simultaneous flow of two or more states of matter, whereas single-phase flow concerns the flow of one state of matter whether in the form of a gas, vapour, or a liquid. The simplest combination is a two-phase flow that can refer to the flow of a gas and a liquid, a gas and a solid, a liquid and a solid, or two immiscible liquids usually with one phase being dispersed within the other. Multi-phase flow systems are therefore considerably more complex than single-phase flow. To illustrate the complexity, the simultaneous flow of oil and gas from wells in offshore oil and gas installations requires immediate separation for which the flow also requires the separation of water and sand, further complicating matters. Multi-phase flow systems may therefore involve combinations of gases, vapours, liquids, immiscible liquids, as well as solids.
