Continuum Physics Unit (Gustavo Gioia)

Continuum Physics Unit

Professor Gustavo Gioia

ggioia at oist.jp

Overview

Our primary research interests are in the mechanics of continuous media with frequent ramifications in geophysics, material science and applied mathematics. We are interested in the peeling and folding of thin solid films, configurational phase transitions in cellular and granular materials, nonlinear fracture mechanics, scaling and size effects in mechanical failure, localized flow in thermoviscoplastic materials, turbulence physics in two and three dimensions, the interaction between turbulence and granular beds, soap-film flows, dense granular flows, and geological fluid dynamics.

Most of our research interests share at least two of the following leitmotifs. (1) A spectrum. (2) A special lengthscale, often associated with a boundary layer or set of boundary layers, that links the spectrum to the phenomenological manifestations of physical behavior. (3) A nonconvex potential. Thus, for example, in our work on turbulence over a rough wall we have shown that momentum is exchanged between flow and wall chiefly by way of a special lengthscale that is a combination of the the viscous lengthscale (which is set by the Reynolds number) and the size of the roughness elements. Once this special lengthscale has been identified, the frictional drag can be computed as a function of the Reynolds number of the flow and the roughness of the wall by intergrating the classical spectrum of Kolmogorov up to the special lengthscale. In another example from our work, the folding of a thin film may be thought of as the process whereby the nonconvex nature of the membraneous energy of the film creates a cascade of increasingly finer foldings that is checked at a special lengthscale set by the bending energy. (In this case, the bending energy is supported on a set of boundary layers.) Here again a special lengthscale acts as a nexus between a spectrum and the phenomenological manifestations of physical behavior.

Our way of tackling a research problem consists in identifying the particular physical phenomenon that is the crux of the problem and then bringing whatever theoretical, experimental, and computational techniques may be needed to elucidate this physical phenomenon. In other words, we keep the focus on the physics rather than on the research techniques.

Within OIST, we share a laboratory and collaborate on many research projects with the Fluid Mechanics Unit.