How Turbulence Works —Turbulence Multifractality Cascade

Abstract

Abstract How turbulence works? What is its function? What drives it? Yet turbulence is poorly understood and poorly ability to calculate. Turbulence is characterized by the cascades of energy across a huge range of scales. But so far, there is still a lack of accurate and universally applicable description of turbulence cascade. We develop the turbulence fractal dynamics to reveals universal law of the turbulence cascade and to provide a universally applicable cascade model of the energy spectrum simply determined by two constants. The atmospheric observation data verify universality and practicality of turbulence cascade model and prove further a huge motion system is composed of turbulence multifractality hierarchical structure with different level turbulence systems driven by the energy injection. The results reveal that the work of a turbulence system is like a heat engine, the energy injection domain continuously absorbs energy from the environment through negative entropy flow, and the energy dissipation domain increasing entropy does work to dissipate energy. The function of turbulence is the energy of a motion system continuously is transferred step by step from higher levels to lower levels through cascade of turbulent vortices, until the energy is converted into molecular heat energy eventually. The results greatly deepen our understanding of the nature of turbulence.