Dwight Barkley (born 7 January 1959) [1] is a professor of mathematics at the University of Warwick. [2] [3]
Barkley obtained his PhD in physics from the University of Texas at Austin in 1988. [4] He then spent one year at Caltech working with Philip Saffman followed by three years at Princeton University where he worked with Yannís Keverkidis and Steven Orszag. In 1992 he was awarded both NSF and NATO postdoctoral fellowships. [4] In 1994 he joined the faculty at the University of Warwick.
Barkley studies waves in excitable media such as the Belousov–Zhabotinsky reaction, heart tissue, and neurons. He is the author of the Barkley Model of excitable media [5] [6] and discoverer of the role of Euclidean symmetry in spiral-wave dynamics. [7]
In 1997, Laurette Tuckerman and Dwight Barkley coined the term "bifurcation analysis for time steppers" for techniques involving the modification of time-stepping computer codes to perform the tasks of bifurcation analysis. [8] He has applied this approach in several areas of fluid dynamics, in particular to stability analysis of the cylinder wake [9] and of the backward-facing step. [10]
Barkley also works on the transition to turbulence in shear flows, including the formation of turbulent-laminar bands [11] [12] and the critical point for pipe flow. [13] [14] Exploiting an analogy with the transition between excitable and bistable media, Barkley derived a model for pipe flow which captures most features of transition to turbulence, in particular the behavior of turbulent regions called puffs and slugs. [15] [16]
He is also known for deriving an equation to estimate how long it will be until a child in a car asks the question "are we there yet?" [17]
In 2005 he was awarded the J. D. Crawford Prize for outstanding research in nonlinear science, "for his development of high quality, robust and efficient numerical algorithms for pattern formation phenomena in spatially extended dynamical systems". [18] [19]
In 2008 he was elected Fellow of the American Physical Society "for combining computation and dynamical systems analyses to obtain remarkable insights into hydrodynamic instabilities and patterns in diverse systems, including flow past a cylinder, channel flow, laminar-turbulent bands, and thermal convection." [20] That same year he was also elected fellow of the Institute of Mathematics and Its Applications. [4]
In 2009-2010 he was a Royal Society–Leverhulme Trust Senior Research Fellow. [21]
In 2016 he was elected Fellow of the Society for Industrial and Applied Mathematics "for innovative combinations of analysis and computation to obtain fundamental insights into complex dynamics of spatially extended systems." [22]
In 2024, he was named a Fluids Mechanics Fellow of Euromech "for his profound contributions to transition to turbulence, nonlinear dynamics, pattern formation, hydrodynamic instabilities, and the Euler singularity through combination of large-scale computing with insightful dynamical systems analysis and modelling". [23]
Laminar flow is the property of fluid particles in fluid dynamics to follow smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing. At low velocities, the fluid tends to flow without lateral mixing, and adjacent layers slide past one another smoothly. There are no cross-currents perpendicular to the direction of flow, nor eddies or swirls of fluids. In laminar flow, the motion of the particles of the fluid is very orderly with particles close to a solid surface moving in straight lines parallel to that surface. Laminar flow is a flow regime characterized by high momentum diffusion and low momentum convection.
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to laminar flow, which occurs when a fluid flows in parallel layers with no disruption between those layers.
Quantum turbulence is the name given to the turbulent flow – the chaotic motion of a fluid at high flow rates – of quantum fluids, such as superfluids. The idea that a form of turbulence might be possible in a superfluid via the quantized vortex lines was first suggested by Richard Feynman. The dynamics of quantum fluids are governed by quantum mechanics, rather than classical physics which govern classical (ordinary) fluids. Some examples of quantum fluids include superfluid helium, Bose–Einstein condensates (BECs), polariton condensates, and nuclear pasta theorized to exist inside neutron stars. Quantum fluids exist at temperatures below the critical temperature at which Bose-Einstein condensation takes place.
In fluid dynamics, the Taylor–Couette flow consists of a viscous fluid confined in the gap between two rotating cylinders. For low angular velocities, measured by the Reynolds number Re, the flow is steady and purely azimuthal. This basic state is known as circular Couette flow, after Maurice Marie Alfred Couette, who used this experimental device as a means to measure viscosity. Sir Geoffrey Ingram Taylor investigated the stability of Couette flow in a ground-breaking paper. Taylor's paper became a cornerstone in the development of hydrodynamic stability theory and demonstrated that the no-slip condition, which was in dispute by the scientific community at the time, was the correct boundary condition for viscous flows at a solid boundary.
Predrag Cvitanović is a theoretical physicist regarded for his work in nonlinear dynamics, particularly his contributions to periodic orbit theory.
Harry Leonard Swinney is an American physicist noted for his contributions to the field of nonlinear dynamics.
Objective-collapse theories, also known spontaneous collapse models or dynamical reduction models, are proposed solutions to the measurement problem in quantum mechanics. As with other interpretations of quantum mechanics, they are possible explanations of why and how quantum measurements always give definite outcomes, not a superposition of them as predicted by the Schrödinger equation, and more generally how the classical world emerges from quantum theory. The fundamental idea is that the unitary evolution of the wave function describing the state of a quantum system is approximate. It works well for microscopic systems, but progressively loses its validity when the mass / complexity of the system increases.
The Orr–Sommerfeld equation, in fluid dynamics, is an eigenvalue equation describing the linear two-dimensional modes of disturbance to a viscous parallel flow. The solution to the Navier–Stokes equations for a parallel, laminar flow can become unstable if certain conditions on the flow are satisfied, and the Orr–Sommerfeld equation determines precisely what the conditions for hydrodynamic stability are.
In continuum mechanics, wave turbulence is a set of nonlinear waves deviated far from thermal equilibrium. Such a state is usually accompanied by dissipation. It is either decaying turbulence or requires an external source of energy to sustain it. Examples are waves on a fluid surface excited by winds or ships, and waves in plasma excited by electromagnetic waves etc.
Robert Harry Kraichnan, a resident of Santa Fe, New Mexico, was an American theoretical physicist best known for his work on the theory of fluid turbulence.
In fluid mechanics, pipe flow is a type of fluid flow within a closed conduit, such as a pipe, duct or tube. It is also called as Internal flow. The other type of flow within a conduit is open channel flow. These two types of flow are similar in many ways, but differ in one important aspect. Pipe flow does not have a free surface which is found in open-channel flow. Pipe flow, being confined within closed conduit, does not exert direct atmospheric pressure, but does exert hydraulic pressure on the conduit.
Philip Geoffrey Saffman FRS was a mathematician and the Theodore von Kármán Professor of Applied Mathematics and Aeronautics at the California Institute of Technology.
(John) Trevor Stuart FRS was a mathematician and senior research investigator at Imperial College London working in theoretical fluid mechanics, hydrodynamic stability of fluid flows and nonlinear partial differential equations.
Uriel Frisch is a French mathematical physicist known for his work on fluid dynamics and turbulence.
Raymond Ethan Goldstein FRS FInstP is the Alan Turing Professor of Complex Physical Systems in the Department of Applied Mathematics and Theoretical Physics (DAMTP) at the University of Cambridge and a Fellow of Churchill College, Cambridge.
Viswanathan Kumaran is an Indian chemical engineer, rheologist and a professor at the Department of Chemical Engineering of the Indian Institute of Science. He is known for his studies on stability of flow past flexible surfaces and is an elected fellow of the Indian Academy of Sciences, Indian National Science Academy and the Indian National Academy of Engineering. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards for his contributions to Engineering Sciences in 2000. A recipient of the TWAS Prize in 2014 and the Infosys Prize 2016 in the Engineering and Computer Science category, Kumaran was listed in the Asian Scientist 100, a list of top 100 scientists from Asia, by the Asian Scientist magazine.
Laurette Stephanie Tuckerman is a mathematical physicist working in the areas of hydrodynamic instability, bifurcation theory, and computational fluid dynamics. She is currently a director of research for the Centre national de la recherche scientifique, at the Physics and Mechanics of Heterogeneous Media Laboratory of ESPCI Paris.
Patrick Henry Diamond is an American theoretical plasma physicist. He is currently a professor at the University of California, San Diego, and a director of the Fusion Theory Institute at the National Fusion Research Institute in Daejeon, South Korea, where the KSTAR Tokamak is operated.
Robert Everett Ecke is an American experimental physicist who is a laboratory fellow and director emeritus of the Center for Nonlinear Studies (CNLS) at Los Alamos National Laboratory and Affiliate Professor of Physics at the University of Washington. His research has included chaotic nonlinear dynamics, pattern formation, rotating Rayleigh-Bénard convection, two-dimensional turbulence, granular materials, and stratified flows. He is a Fellow of the American Physical Society (APS) and of the American Association for the Advancement of Science (AAAS), was chair of the APS Topical Group on Statistical and Nonlinear Physics, served in numerous roles in the APS Division of Fluid Dynamics, and was the Secretary of the Physics Section of the AAAS.
Turbulent phenomena are observed universally in energetic fluid dynamics, associated with highly chaotic fluid motion, and typically involving excitations spreading over a wide range of length scales. The particular features of turbulence are dependent on the fluid and geometry, and specifics of forcing and dissipation.