BEHAVIOR OF AN INERT SCALAR UNDER THE DIFFERENT SMALL SCALE TOPOLOGIES OF A TURBULENT FLOW

The physical phenomena that determine the evolution and characteristics of a scalar in a turbulent flow are studied using direct numerical simulation (DNS) of both the scalar and the velocity fields. The statistics of essential magnitudes related to the mixing, such as the scalar diffusion, the scalar dissipation or the variance is analysed for the different small scale dynamical structures in the flow. This study is conducted in the framework of the Topological Methodology introduced by Chong et al (1990), which classifies the different small scale dynamics in terms of velocity gradient invariants. From this investigation, the scalar properties display different features for each of the four topologies considered.