John O. Dabiri
Phys. Rev. Fluids 4, 110501 (2019) – Published 18 November, 2019
Physical Review Fluids publishes a collection of papers associated with the invited talks presented at the 71st Annual Meeting of the APS Division of Fluid Dynamics.
The broad relevance of fluid mechanics to biology has been increasingly appreciated by engineers and biologists alike, leading to continued expansion of research in the field of biological fluid dynamics. A selection of classic and recent work that can guide future research is highlighted.
A dynamical system is described that captures the near-singular character of vortex reconnection, thus indicating how enstrophy in turbulent flow can become infinite in the zero-viscosity limit. Similarities with the near-singular behavior in the problem of cusp-formation at a free surface are identified.
Professor Itai Cohen describes the challenge of studying insect flight and, in the accompanying video recording of his invited lecture from the 71st annual APS DFD meeting, illustrates the mechanisms used by insects to control this behavior and achieve spellbinding acrobatic feats.
The flow conditions of a full-scale wind turbine are reproduced in a laboratory with dynamic similarity, using a pressurized wind tunnel. Aerodynamic scale-effects persist at higher Re than previously believed, and it is shown that the boundary layer state is critical for turbine performance.
A restricted nonlinear representation of the flow as a streamwise constant large-scale interacting with dynamically restricted perturbations faithfully reproduces low order statistics, cross-stream structures and energy transport in turbulent channels, at vastly reduced computational costs.
Colloidal biology is a frontier of exploration in biological cells bridging the operational gap between structural biology (atomistic resolution over nanoseconds) and systems biology (minutes of operation, no spatial resolution). Colloid physics bridges this gap where much of cell machinery operates.
Artistic painting is analyzed with fluid mechanics. We identify hydrodynamic instabilities which are either prevented or induced to create textures of aesthetic value. In watercolor painting the ‘coffee stain’ instability can be induced or prevented by varying pigment type and amount and paper wetness.
Simple models for hairy surfaces interacting with flows are derived, and used to extract optimization and design principles in idealized contexts. Reconfiguration, in which flow couples to the hairs geometric configuration, is investigated along with drainage of thin films through beds of hairs.
