Linearly forced isotropic turbulence at low Reynolds numbers

Wouter J.T. Bos (1) , Faouzi Laadhari (1) , Wesley Agoua (1)

1 LMFA - Laboratoire de Mecanique des Fluides et d'Acoustique

We investigate the forcing strength needed to sustain a flow using linear forcing. A critical Reynolds number R_c is determined, based on the longest wavelength allowed by the system, the forcing strength and the viscosity. A simple model is proposed for the dissipation rate, leading to a closed expression for the kinetic energy of the flow as a function of the Reynolds number. The dissipation model and the prediction for the kinetic energy are assessed using direct numerical simulations and two-point closure integrations. An analysis of the dissipation-rate equation and the triadic structure of the nonlinear transfer allows to refine the model in order to reproduce the low-Reynolds-number asymptotic behavior, where the kinetic energy is proportional to R − R_c.

Domaines: Mécanique des fluides [physics.class-ph]

Wouter J.T. Bos, Faouzi Laadhari, Wesley Agoua. Linearly forced isotropic turbulence at low Reynolds numbers. Physical Review E , 2020, 102, ⟨10.1103/PhysRevE.102.033105⟩. ⟨hal-02933727⟩