Free-Surface Vortical and Turbulent Flows

The major research objectives of this project are to improve the understanding and modeling of complex flows and, ultimately, to predict and control them.

The physics are fundamental to free-surface phenomena and processes, such as vortex-free surface interactions, free-surface turbulence, the turbulent air-water interface, wind-wave interactions, post-wave-breaking processes and wakes. The mechanisms are responsible for, and directly affect, the observed wakes of ships, the remote sensing of the ocean surface and the transfer of energy, momentum, heat and gases at air-water or other gas-liquid interfaces. The approach being taken to address specific problems in this research area is a coordinated numerical, experimental and theoretical effort; the key to progress is making quantitative comparisons between numerical simulations and experimental measurements guided by theoretical analyses. Using direct numerical simulations (DNS) and large-eddy simulations (LES) of the Navier-Stokes equations with full viscous free-surface boundary conditions, with or without soluble and insoluble surfactants, the facultystudent research team has been able to provide mechanistic and topological descriptions of the intricate processes involved, and to contrast them to the situations where the free surface is replaced (in approximation) by free-slip or no-slip walls. This computational effort is supported by quantitative digitalparticle- imaging velocimetry (DPIV) mapping of time-dependent laboratory flows.