Applied Math Colloquium | Arezoo Ardekani, Swimming and settling in density stratified fluids

MC 5501 

Speaker

Arezoo Ardekani, School of Mechanical Engineering, Purdue University

Title

Swimming and settling in density stratified fluids

Abstract

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. We explore the effects of stratification on the fundamental hydrodynamics of settling particles, rising drops, and small organisms. Our results show that the presence of vertical density gradients in the water column can substantially affect the settling dynamics of a particle, interaction between a pair of particles, and settling rates and microstructure of suspension of particles. We further demonstrate an unexpected effect of buoyancy, potentially affecting a broad range of processes at pycnoclines in oceans and lakes. In particular, stratification has a major effect on the flow field, energy expenditure, and nutrient uptake of small organisms.