Boye Ahlborn, Professor EmeritusDiplom. Kiel (60); Dr. rer. nat., Munich (64)
I like to work on fluid flow problems, including turbulence, and energetics of heat flow, and in physical principles that are used by animals.
Examples of practical importance are the generation of drag, the production of propulsive thrust of aquatic animals, and thermodynamical effects in confined vortex systems (Ranque Hilsch vortex tube).
Form drag is connected to the mechanism of vortex shedding, which can be considered as the first stage of turbulent motion.
The hall mark of turbulence is the existence of distributed coherent structures. These "eddies" contain kinetic- and internal energy. Coherent structures are produced, they interact with each other, with fixed walls, and with moving structures in the fluid, and they are eventually destroyed. These dynamic processes can be characterized by production- and decay rates, and by statistical energy distribution functions. I am interested in fleshing out such a thermodynamic - statistical model of turbulence.
Since about 1990 I have been interacting with colleagues, R.W. Blake and J. Gosline from the Department of Zoology. A new lecture course, has evolved out of this collaboration, called
" P438/Biol 438, Zoological Physics:, How Animals make Use of Physics",
This interdisciplinary course, given at UBC since 1995, is design for senior undergraduate students from all Science departments who have taken at least an introductory course in Physics, and have some background in Biology.
Zoological Physics deals with tissue, organs, and with the whole body, and it portrays how animals interact with their environment. Physics concepts from thermodynamics, statics, dynamics, fluid flow, optics, acoustics, electricity, and magnetism are applied to make quantitative predictions about the actions, the body design, and the physical limitations of animals. This approach provides the methods to answer questions such as
After looking at such issues one realizes that animals on every level of evolution have turned to their advantage the principles of physics, millions of years before they were discovered by scientists and engineers.
Boye K. Ahlborn, "Thermodynamic Limits of Body Dimension of Warm Blooded Animals"
.J.Non Equilibr.Thermodynamics , 25, 87-102 (2000).
B.K.Ahlborn and R.W.Blake, "Lower size limit of aquatic mammals", Am.J.Phys. 67, 920-922 (1999).
B.Ahlborn, J.U. Keller and E. Rebhan, "The heat pump in a vortex tube" J.Non Equilibr. Thermo Dynamics 23, 159-165 (1998).
B.Ahlborn, M.Lefrancoise and H.D.King. "The clockwork of vortex shedding", Physics Essays, Vol 11,No1, 144-154, (1998)
B.Ahlborn S.Chapman, R. Stafford, R.W.Blake and D.Harper, "Experimental simulation of the thrust phases of fast-start swimming of fish ", J.Experimental Biology,200,2301- 2312 (1997)
M. Lefrancois and B. Ahlborn, "Phase front analysis of vortex streets" P.Fluids 6, 2021- 2031, (1994),
Boye Ahlborn, David G. Harper, Robert W. Blake, Dorit Ahlborn, and Micheal Cam, "Fish without Footprints", J.Theor. Biol. 148, 521-523 (1991),
S.Loewen, B.Ahlborn, and A.B.Filuk, "Statistics of surface flow structures on decaying grid turbulence". P.Fluids 29, 2388-2397 (1986).
F.L. Curzon and B. Ahlborn, "Efficiency of Carnot engine at maximum power output", Am. J. Phys. 43, 22-24 (1975).