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Getting flow regimes right is important in many industrial applications, e.g. nozzle design, inline mixing etc. This is challenging, as multiphase flow is complex. For example, in gas-liquid flow, gas may flow continuously as a stratified layer, be dispersed as bubbles, or flow in intermittent slugs.

Flow regime maps are visual representations of the relationship between flow conditions and the expected distribution of phases. Although multiphase behavior is complex, it is rooted in the force balances on the fluids and can be described in terms of non-dimensional variables. Flow regime maps generalize experimental data in terms of such variables, providing a tool for estimating expected flow regimes at various conditions and scales.

The Spedding map for air-water flow in horizontal pipes is an example in terms of two parameters, the liquid to gas flow ratio and the Froude number. The expected flow regime can be validated as was done here by high-speed imaging in a pressurized visualization cell. The videos correspond well with the flow regimes expected from the map. Use of data like this along with experimental validation is one of Coanda’s approaches to solving multiphase flow problems.