Dataset for: Biomimetic models of fish gill rakers as lateral displacement arrays for particle separation

Ram suspension-feeding fish such as herring use gill rakers to separate
small food particles from large water volumes while swimming forward with
an open mouth. Fish gill raker function was tested using 3D-printed
conical models and computational fluid dynamics (CFD) simulations over a
range of slot aspect ratios. (See CFD simulation output in Dryad dataset:
case and data files for ANSYS Fluent 19.1 CFD simulations.) Our hypothesis
predicting the exit of particles based on mass flow rates, dividing
streamlines (i.e., stagnation streamlines) at the slots between gill
rakers, and particle size was supported by the results of experiments with
physical models in a recirculating flume. (See R code with embedded
comments in Dryad dataset to test Hypotheses 1 and 2 for particle
exit/trapping.) Particle movement in suspension-feeding fish gill raker
models was consistent with the physical principles of lateral displacement
arrays (“bump arrays”) for microfluidic and mesofluidic separation of
particles by size. Although particles were smaller than the slots between
rakers, particles skipped over the vortical region that was generated
downstream from each raker. Particles “bumped” on anterior raker surfaces
during posterior transport. (See particle movement data in Dryad dataset:
three files for particle contact, exit, and retention in the physical
models.) Experiments in a recirculating flume demonstrated that the
shortest distance between the dividing streamline and the raker surface
preceding the slot predicts the maximum radius of a particle that will
exit from the model by passing through the slot. This theoretical maximum
radius is analogous to the critical separation radius identified with
reference to the stagnation streamlines in microfluidic and mesofluidic
devices that use deterministic lateral displacement and sieve-based
lateral displacement. These conclusions provide new perspectives and
metrics for analyzing crossflow and cross-step filtration in fish with
applications to filtration engineering.