Energy transfer and dissipation in forced isotropic turbulence

A model for the Reynolds-number dependence of the dimensionless dissipation rate C was derived from the dimensionless Kármán-Howarth equation, resulting in C=C,+C/RL+O(1/RL2), where RL is the integral scale Reynolds number. The coefficients C and C, arise from asymptotic expansions of the dimensionless second-and third-order structure functions. This theoretical work was supplemented by direct numerical simulations (DNSs) of forced isotropic turbulence for integral scale Reynolds numbers up to RL=5875 (Rλ=435), which were used to establish that the decay of dimensionless dissipation with increasing Reynolds number took the form of a power law RLn with exponent value n=-1.000±0.009 and that this decay of C was actually due to the increase in the Taylor surrogate U3/L. The model equation was fitted to data from the DNS, which resulted in the value C=18.9±1.3 and in an asymptotic value for C in the infinite Reynolds-number limit of C,=0.468±0.006.