[MARMAM] New paper on the hydrodynamics and drag of foraging Balaenid whales

Jean Potvin potvinj at slu.edu
Wed Apr 12 08:53:41 PDT 2017

Greetings all!

It is a pleasure to announce the publication of our latest paper, which
just appeared in PLoS One:

*Oral Cavity hydrodynamics and drag production in Balaenid whale suspension

By J. Potvin and A. J. Werth

Balaenid whales feed on large aggregates of small and slow-moving prey
(predominantly copepods) through a filtration process enabled by baleen.
These whales exhibit continuous filtration, namely, with the mouth kept
partially opened and the baleen exposed to oncoming prey-laden waters while
fluking. The process is an example of crossflow filtration (CFF) in which
most of the particulates (prey) are separated from the substrate (water)
without ever coming into contact with the filtering surface (baleen). This
paper discusses the simulation of baleen filtration hydrodynamics based on
a type of hydraulic circuit modeling commonly used in microfluidics, but
adapted to the much higher Reynolds number flows typical of whale
hydrodynamics. This so-called *Baleen Hydraulic Circuit* (BHC) model uses
as input the basic characteristics of the flows moving through a section of
baleen observed in a previous flume study by the authors. The model has
low-spatial resolution but incorporates the effects of fluid viscosity,
which doubles or more a whale’s total body drag in comparison to
non-feeding travel. Modeling viscous friction is crucial here since
exposing the baleen system to the open ocean ends up tripling a whale’s
total wetted surface area. Among other findings, the BHC shows how CFF is
enhanced by a large filtration surface and hence large body size; how it is
carried out via the establishment of rapid anteroposterior flows
transporting most of the prey-water slurry towards the oropharyngeal wall;
how slower intra-baleen flows manage to transfer most of the substrate out
of the mouth, all the while contributing only a fraction to overall oral
cavity drag; and how these anteroposterior and intra-baleen flows lose
speed as they approach the oropharyngeal wall.

This is an open-access paper, which can be downloaded here:

Jean Potvin
potvinj at slu.edu
Alex Werth
AWerth at hsc.edu
Dr. Jean Potvin
Dept. Physics
Saint Louis University
Shannon Hall, Room 111
3511 Laclede Ave.
St. Louis MO 63103
(314) 977-8424
"So many ideas, so little time..."
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