Convection, Pressure and Dissipation in Three-Dimensional Turbulence

The roles of the convection, pressure and dissipation are investigated in the equation for longitudinal velocity increment over the inertial range of stationary incompressible turbulence. The convection is the motor of the turbulence, while the pressure screens the convection increasing with the intensity of increment. The combined effect of the convection and the pressure is balanced by the dissipation for structure functions of order not less than five. At fourth order the dissipative term is irrelevant.