An outline is given of the physical concepts and mathematical formulations of a multi-fluid model (MFM) of turbulence.
Similarities to, and differences from, earlier turbulence models are described.
References to recent works on MFM are provided, but with only brief summaries of their contents, the aim of the present paper being to collect and explain all the relevant ideas, without distraction by particular examples.
Consideration is given to the advantages likely to be derived from applying the MFM to practical problems of engineering and environmental science.
Although MFM is already capable of being applied to many practical problems, especially those involving combustion processes or other chemical reactions, research and development work can be foreseen as likely to improve its acceptability, its realism and its economy. A classified list of such tasks is provided.