Professor Deegan’s research focuses on the dynamics of non-equilibrium systems. As a system, such as a fluid or a solid, is driven from equilibrium, it undergoes a series of transitions to progressively more organized dynamics. Everyday examples of this phenomenon are the bands of Jupiter, the Giant’s Causeway, and the crumpled edges of lettuce leaves. Dynamical transitions share many similarities with thermally driven phase transitions, which suggests the existence of a yet-to-be-discovered general principle for dynamical transitions equivalent to the minimum free energy principle of thermodynamics.
Professor Deegan studies dynamical transitions though table-top experiments with the aim of understanding the origin of this behavior in each specific case and in general. His research covers a broad range of phenomena from drying drops to bursting balloons to vibrated slurries. Currently, he is investigating drop impact and the instability that produces the famous Edgerton crown, and pattern formation in chemical reactions and complex fluids.
Wavelength Selection in the Crown Splash, (L. V. Zhang, P. Brunet, J. Eggers, & R.D. Deegan), Physics of Fluids 22, 122105 (2010).
Stress Hysteresis as the Cause of Persistent Holes in Particulate Suspensions, (R.D. Deegan), Physical Review E 81, 036319 (2010).
Motion of a Drop Driven by Substrate Vibrations, (P. Brunet, J. Eggers, & R.D. Deegan), European Physical Journal 166, 11 (2009).
Crumpling, Buckling, and Cracking: Elasticity of Thin Sheets, (M. Marder, R.D. Deegan, & E. Sharon), Physics Today 60, 33 (2007).