Speaker

Dr. Takeshi Matsumoto
Department of physics, Kyoto university

Title

Peculiar decay of turbulence: 3D Navier-Stokes and shell model

Abstract

The old problem on free decay of turbulence is studied numerically. Our initial energy spectrum for the three-dimensional incompressible Navier-Stokes eqs. is localized in high wavenumbers. The initial phases of the velocity Fourier modes are random without correlation. In this case we show that the decrease of the total kinetic energy is not a simple power law, but with a peculiar logarithmic correction as a long transient. As a second topic, we study the decay problem of the shell model with the standard initial energy spectrum   for small wavenumbers. We show numerically that the power-law exponent of the decay of the shell model is independent of the spectral exponent a