Roles of convection, pressure, and dissipation in three-dimensional turbulence

We investigated the roles of the convection, pressure, and dissipation terms in the equation for the longitudinal velocity increment, with the help of the DNS data on 1024(3). The pressure screens the convection growing as the intensity of fluctuation increases. The dissipation term is found to make no direct contribution to the fourth order structure function; the structure functions of order not less than 5 are affected by the dissipative structure as far as the scaling is concerned. A reason is also given for the observation by Stolovitzky et al. [Phys. Rev. E 48, R3217 (1993)] that the scaling of the (2m)th order structure function is more similar to that of the (2m-1)th order structure function than that of (2m+1)th order structure function.