Berlin 2005 – scientific programme

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DY: Dynamik und Statistische Physik

DY 10: Fluid Dynamics I

DY 10.7: Talk

Friday, March 4, 2005, 11:45–12:00, TU H3010

Influence of noise on anomalous transport in steady viscous flows — •Michael Zaks — Institut für Physik, Humboldt-Universität Berlin

In time-independent plane flows of viscous fluids past arrays of vortices or solid obstacles there can be neither turbulence nor Lagrangian chaos. Nevertheless, such fluid motions may exhibit unusual transport properties which originate in the slowdown of tracers in vicinities of stagnation points or near the solid borders with no-slip conditions. We discuss modifications which appear if tracers are viewed as passive Brownian particles in noisy environments. In flows through periodic lattices of solid obstacles the anomalous transport yields to normal diffusion. For flows past arrays of vortices the outcome is different. Here introduction of noise allows the tracers to penetrate across the separatrices into the vortices which thus turn into a kind of traps; this enhances the spreading, ensuring long epochs of nearly ballistic transport.