Tue February 26th 2019
16:00 – 17:00
ZH286 		Seminar Modelling and Computation of Interfaces in Turbulent Multiphase Flows
Alfredo Soldati

Details:

Droplets carried in turbulent fluids rely, for their existence, on tiny interfaces. Interfaces are not property
of the drop or of the the carrier fluid and are inherently a non-place. However, in environmental and
industrial processes, their role is enormously important since it is across the interfaces that momentum,
heat and mass transfer fluxes coupling the drop to the carrier fluid occur: the accurate determination of
their position, shape and interaction with the fluid turbulence is crucial to predict physical phenomena,
and industrial and environmental processes. To this aim, Direct Numerical Simulation (DNS) of turbulence
and accurate tracking of the interface are required, but the range of scales involved for most of
practical environmental and industrial applications is so wide that performing this task is a formidable
challenge for present day computers: The grid resolution for DNS of turbulence is of the order of the
Kolmogorov scale, but of course physical interfaces have a much smaller scale (order of few molecules)
making the direct resolution unfeasible.
In this talk, we will briefly review the current computational methodologies used to interfaces and the
we will focus on the phase-field approach in turbulent flows: In this Eulerian approch, the phase distribution
is described by the order parameter . We will examine several flow instances and phenomena
ranging from turbulent stratified flows to turbulent dispersion of drops and bubbles so to reveal potentials
and limitations of the phase-field method. Interface interactions with turbulence, coalescence and
breakup phenomena for different values of fluids density and viscosity will be discussed in connection
with the characteristics of turbulence. Finally, the physics modelling and the method required to include
the effect of surfactants will also be examined.


Short Bio
Alfredo Soldati is Professor of Fluid Mechanics at the Institute of Fluid Mechanics and Heat Transfer at the Technische Universitat Wien (Austria) and at University of Udine (part-time appointment). Fellow of the American Physical Society, recipient of the ASME Knapp award and of the ASME Lewis F. Moody award, recipient of the 2018 Panetti-Ferrari prize from Accademia delle Scienze di Torino, Dr. Soldati is Editor in Chief of International Journal of Multiphase Flow and Rector at the International Center for Mechanical Sciences (CISM).
Go back to the agenda.