Hydrothermal flames have become a very important field of study, especially for supercritical water oxidation. In supercritical water oxidation hazardous, toxic or non-biodegradable aqueous organic waste water streams can be efficiently destructed. Supercritical water oxidation takes place in a aqueous environment above the supercritical point.

In the case of turbulent flow, micromixing models are needed.
In this work, three different mixing models are analysed in a hydrothermal flame environment. These models are Interaction by Exchange with the Mean, Coalescence/Dispersion and the Mapping Closure model. When the mixing is done around temperatures far below or far above the pseudocritical temperature all models gave the same evolution of average temperature. However when the mixing is done around the pseudocritical temperature the differences are large. The Mapping Closure model is best in agreement with the Navier-Stokes equations so it is advised to use that model when simulating mixing around the pseudocritical temperature.