J. R. de Bruyn

I will be moving to the University of Western Ontario effective March 1, 2005, where I will become Chair of the Department of Physics and Astronomy. I am not taking any more students to work in my group at MUN. Students interested in working with me should apply to the University of Western Ontario. Please contact me for more information!

 B.Sc. University of British Columbia, 1979
M.Sc. Queen's University, 1981
Ph.D. University of British Columbia, 1987

Experimental condensed matter physics

My research centers on the dynamics of systems driven out of equilibrium. I am currently involved in projects in a number of areas, including pattern formation, granular flows, and non-Newtonian fluids.

Pattern formation: Many nonlinear, nonequilibrium systems will undergo a transition from a spatially uniform state to one characterized by a spatially organized pattern. When driven further, the pattern may become chaotic in space and/or time. Pattern-forming transitions are in many ways analogous to equilibrium phase transitions. I do experiments to study the formation, stability and dynamics of such patterns in a variety of systems, including fluids and granular materials.  Measurements are made using  optical techniques and through analysis of video images.
	Granular flows: Granular materials (like sand, for example) can behave like solids, fluids, or gases, depending on the situation. If you pour sand from a jar, it flows like a fluid, but if you stand on a pile of sand, it supports your weight like a solid would. I am interested in the analogy between granular flows and conventional fluids. To what extent does a continuum description of granular material (analogous to the Navier-Stokes equations used in fluid dynamics) describe granular flows? When do the peculiar properties of granular fluids start to matter? I do experiments on granular flows, using high-speed video and other visualization methods, to investigate these questions.
Non-Newtonian fluids: Newtonian fluids like water have a viscosity that is constant, independent of the flow state of the fluid. Non-Newtonian fluids, in contrast, have a viscosity that is a function of strain rate. In particular, yield-stress fluids behave like a solid if the applied stress is smaller than a particular value, but flow like a fluid if the stress is above that value. Ketchup is an example; so is mud. I am interested in the origin of the yield stress, and in the relationship between the small-scale structure of the material and its large scale properties. We are investigating these questions through a number of different experiments using rheology, ultrasonics, light scattering, and flow visualization.

 I collaborate a lot with my brother-in-law, whose research group has a much better web page than I do.

 Teaching:

• Physics 1051: General Physics II
• Physics 1054: Computational Physics and Data Analysis
• Physics 3550/Engineering 3821: Electric Circuits
• Physics 3220: Classical Mechanics
• Physics 3150: Astrophysics

Coordinates:

Phone: (709) 737-2113
Fax: (709) 737-8739
email: jdebruyn@kelvin.physics.mun.ca

Selected recent publications

• S.S. Mao, J. R. de Bruyn , Z.A. Daya, and S.W. Morris, ``Boundary-induced wave number selection in a one-dimensional pattern-forming system,'' Phys. Rev. E 54, R1048, 1996.
• J. R. de Bruyn , E. Bodenschatz, S.W. Morris, S.P. Trainoff, Y. Hu, D.S. Cannell, and G. Ahlers, ``Apparatus for the study of Rayleigh-Benard convection in gases under pressure,'' Rev. Sci. Instr. 67, 2043, 1996.
• J. R. de Bruyn , ``Early stages of ramified growth in quasi-two-dimensional electrochemical deposition,'' Phys. Rev. E 53, R5561, 1996.
• J. R. de Bruyn , ``Physical and electrochemical contributions to the cell voltage in the thin-layer electrochemical deposition of copper at constant current,'' Phys. Rev. E 56, 3326, 1997.
• Z.A. Daya, V.B. Deyirmenjian, S.W. Morris, and J. R. de Bruyn , ``Annular electroconvection with shear,'' Phys. Rev. Lett. 80 , 964, 1998.
• J. R. de Bruyn , C. Bizon, M.D. Shattuck, D. Goldman, J.B. Swift, and H.L. Swinney, ``Continuum-type stability balloon in oscillated granular layers,'' Phys. Rev. Lett. 81, 1421, 1998.
•  K. A. Shorlin, J. R. de Bruyn, M. Graham, and S. W. Morris, ``Development and geometry of isotropic and directional shrinkage-crack patterns,'' Phys. Rev. E 61, 6950, 2000.
• J. R. de Bruyn, J. K. C. Lewis, M. R. Morrow, S. P. Norris,  N. H. Rich, J. P. Whitehead, and M. D. Whitmore, ``Expanding the role of computers in physics education: A computer-based first-year course on computational physics and data analysis,'' Can. J. Phys. 80, 855 (2002).
• J. R. de Bruyn, B. Lewis, M. D. Shattuck and H. L. Swinney, ``Spiral patterns in oscillated granular layers,'' Phys. Rev. E 63, 041305, 2001.
• P. Habdas, M. J. Case, and J. R. de Bruyn, ``Behavior of sink and source defects in a one-dimensional traveling finger pattern,'' Phys. Rev. E 63, 066305, 2001.
• J. R. de Bruyn, P. Habdas, and S. Kim, ``Fingering instability of a sheet of yield-stress fluid,'' Phys. Rev. E 66, 031504, 2002.

Information about graduate studies at Memorial University.