Lagrangian evolution of non-Gaussianity and material deformation in restricted Euler dynamics
Seminar Room 1, Newton Institute
Small-scale intermittency in fluid turbulence refers to the infrequent but strong bursts in the signals of small scale parameters. These bursts display highly non-Gaussian statistics, and its prediction poses serious challenges to turbulence research. Based on the restricted Euler approximation, and following the recent idea of tetrad dynamics, we derive a simple system of equations for the short-time Lagrangian evolution of velocity and passive scalar increments. The system reproduces several important intermittency trends observed in turbulence. A generalization to rotating turbulence shows that system captures some qualitative effects of rotation. An analytic solution to the material deformation in restricted Euler dynamics, obtained following the same idea, is also presented.