Kollokvium på NILU
Den gåtefulle blandingen i turbulente prosesser
Special Seminar: Sniffing-Out the Riddle of Turbulent Mixing
Tuesday 12 May 2009 12:00-13:00 at NILU's Auditorium. Michael S. Borgas, CSIRO Light Metals Flagship, Victoria, Australia.
Turbulence is an important class of self-organised complex systems in nature. The 'scientific' task, more-or-less, is to understand how to extract useful information from a turbulent process. An interesting example is the sense of smell in the environment. Animals use trails of smell, embodied as tracer chemicals fluctuating in turbulent winds, for biological functions like tracking, navigation, and identification.
In particular, industrial smells, say from light-metals-smelting pollution, affect humans and their governance in modern society. Turbulence plays a vital role, whether as boundary-layer fluxes of energy or momentum, determining the wind and atmospheric mixing, or as the fine-scaled interleaving of a plume with clean air by the cascade of energy to molecular scales.
A new and useful way to extract understanding is to consider the plume as coded information rather than chemical concentration, and with turbulence regarded as a maximum-entropy mixer of information.
This gives new understanding, both of plumes in the surface layer, and of the perception of plume smell, and therefore ultimately to the means of regulating smell as an airborne pollutant. In this example from nature, the riddle of turbulence is connected to the riddle of conscious sensory perception, and the maximum-entropy mixing laws turn out to be consistent with Weber-Fechner laws for smell intensity and other practical aspects of smell perception.