Transport of particles, drops, and small organisms in density stratified fluids

Department of Aerospace and Mechanical Engineering

University of Notre Dame

Many aquatic environments are characterized by regions where water density varies over depth, often due to temperature or salinity gradients. These 'pycnoclines' are associated with intense biological activity and can affect carbon fluxes by slowing the descent of particles. Despite this, the fundamental fluid dynamics of settling and swimming in a stratified fluid have remained largely unexplored. I take first strides into this area by rationalizing the effects of stratification by conducting a broad, in-depth investigation on fundamental hydrodynamics of vertical migration of small organisms, settling particles, and rising drops. These results demonstrate an unexpected effect of buoyancy, potentially affecting a broad range of abundant processes at pycnoclines in oceans and lakes.