Lagrangian statistics in isotropic turbulent flows with deterministic and stochastic forcing schemes

Artificial input of energy into the flow is necessary to create and maintain a statistically stationary isotropic turbulence for sampling in studying the statistics. Due to the nonlinear coupling among different Fourier modes through the triadic interaction, whether or not various forcing schemes affect the statistics in turbulence is an important and open question. We present detailed comparison of Lagrangian statistics of fluids particles in forced isotropic turbulent flows in 1283, 2563, and 5123 simulations, with Taylor-scale Reynolds numbers in the range of 64–171, using a deterministic and a stochastic forcing scheme, respectively. Several Lagrangian statistics are compared, such as velocity and acceleration autocorrelations, and moments of Lagrangian velocity increments. The differences in the Lagrangian statistics obtained from the two forcing schemes are shown to be small, indicating that the isotropic forcing schemes used have little effects on the Lagrangian statistics in the isotropic turbulence.