The role of active Navier–Stokes angular momentum in identifying small-scale turbulence behavior

This work investigates the role of an active Navier–Stokes angular term, inherent in micropolar theory, in characterizing small-scale turbulence behavior. By incorporating the micropolar viscosity ratio m, a modified Navier–Stokes equation is derived that allows for fine-tuning of small-scale turbulence intensity without changing the bulk flow properties. Direct numerical simulations of turbulent micropolar Poiseuille flow show that increased m intensifies the near-wall turbulence and enhances dissipation of turbulent kinetic energy, particularly within the viscous sublayer. The decisive role of small-scale structures in micropolar flows is further enhanced here by the analysis of helicity, where acceleration of velocity–vorticity alignment is observed. The outcome underlines the potential of a micropolar model in advancing studies and modeling of turbulence.