Nonlinear Properties of Materials.
LA JOLLA INST CA CENTER FOR THE STUDY OF NONLINEAR DYNAMICS
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Investigation is made on such diverse phenomena as turbulence, extreme properties of stochastic systems, the statistics of nonlinear wave-wave interactions and the detection of clustered events. One of the theories developed to explain the transition from laminar to turbulent flow is through the use of intermittent turbulent bursts interacting with the laminar flow to generate more bursts and thus form a cascade to a fully developed turbulent state. Thus, the statistical distribution of such bursts is important in determining the rate of transition from laminar to turbulent fluid flow and can thereby strongly influence the drag properties of fluid flowing past a body. A second process in which intermittency is important is the anomolous transport of charge in amorphous materials. The current flow in these materials exhibits a clustering of events in time not unlike that observed in fluid turbulence. In both of these systems the physical observables, e.g. the correlation function, exhibit scaling behavior with exponents characteristic of the process. A final example is the stress relaxation of polymers, in which case the scaling behavior effects such material properties as brittleness, dielectric loss, etc. A new random walk model is developed which greatly increases our understanding of such processes.
- Miscellaneous Materials
- Fluid Mechanics