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Animals in fluid motion
DTU Aqua, Charlottenlund Slot, Jægersborg Allé 1, 2920 Charlottenlund
Wednesday 4 September 2013, 13.00 - 16.30

Birds, insects, fish and smaller animals move in air and water. The fluid dynamics of how they fly and get propulsion is a large research area. In this seminar, we will get presentations representing both the physisist's and the biologist's view on these problems.  

12.30 Registration
13.00 Welcome 
13.10 Introduction to flight and propulsion of animals
Dr. Anders Andersen, DTU Physics, Denmark

Swimming bacteria and small micron size plankton organisms experience a friction dominated fluid world characterized by low Reynolds numbers whereas fish and birds at higher Reynolds numbers are able to shed vortices and use inertial effects to propel themselves. I will describe some of the fascinating biological fluid dynamics of locomotion at low and high Reynolds numbers. In particular I will discuss the basis of the drag-based locomotion used by swimming organisms at low Reynolds numbers, the importance of the Reynolds number for ambush-feeding zooplankton, and the thrust and wake structures created by a simple actuated model foil at high Reynolds number.
Slides as PDF

13.40 Flight of insects
Professor Jane Wang, Cornell, USA

I will discuss fluid dynamics experienced by insects: how dragonflies and fruit flies work with unsteady flows to take off, to fly efficiently, to balance in air, and to turn quickly.

14.25 Coffee Break
14.55 Flight of birds and bats
Professor Anders Hedenström, Lund University, Sweden

Birds and bats have evolved flight independently from each other, where birds originate from dinosaurs and bats are mammals. The current bird and bat fauna are the result of more than 65 my of parallel evolution. The flight apparatus differ in many ways, both in the arrangement of flight muscles and the wing structure. Yet, the flight performance is surprisingly similar between the two groups, while birds are slightly more efficient in cruising flight and bats are generally more manoeuvrable. Both bird and bat species have evolved the capacity to enhance lift in slow flight and hover by using a leading edge vortex during the downstroke. Endurance flight capacity in birds outperform any manmade autonomous flight vehicle of similar size, which is the result of a multitude of adaptations. I will show examples of the results of studies of bird and bat flight in the Lund University wind tunnel, with some comparison of flight performance of birds in the wild.
Slides as PDF

15.40 Fluid mechanics of swimming and feeding in small aquatic animals
Professor Thomas Kiørboe, Centre of Ocean Life, DTU Aqua, Denmark

Marine zooplankton, small mm-sized animals, swim and feed in a nutritionally dilute and viscous environment. To get enough food they have daily to collect microscopic phytoplankton particles from a volume of sticky water that corresponds to about 106 times their own body volume. And when swimming and feeding they may generate far extending fluid disturbances that attract their predators.  I will describe how these small organisms manage the fundamental dilemma of simultaneously being a predator and a prey in a low Re fluid environment that is fundamentally different from the environment in which we live. I will show high-speed videos of their feeding and swimming, visualize the flow they generate using PIV, and present simple analytical as well as CFD models that we use to understand how these small organisms optimize the tradeoffs associated with feeding and swimming.
Slides as PDF

16:10 Closing remarks

Members of DANSIS can participate in the seminar free of charge. Non-members are also invited to participate at a fee of 400 DKK.

DANSIS - The Danish Society for Industrial Fluid Dynamics     Email: dansis@dansis.dk