The dynamics behind the multiscale energy transfer in turbulent flows is investigated in a numerical simulation of homogeneous isotropic turbulence (HIT). The investigation relies on conservation laws derived from the incompressible morphing continuum theory on the basis of the Boltzmann-Curtiss kinetic theory. The resulting conservation laws reveal the existence of small-scale routes for the flow of energy, which broadens the view on energy cascade (forward or inverse). The comparison of the turbulence characteristic with the reference study indicates that the turbulence features in both frameworks are equivalent at the global and small-scales; however, the presented framework shows a more detailed energy flow mechanism, while maintaining the same global dissipation rate. The study reveals that the theoretical small-scale structures can represent the small-scale structures in the turbulent flow. Finally, the energy analysis is carried out based on the presented conservation laws. The analysis reveals that at the small-scale both forward and inverse energy cascade exist in HIT; however, an overall negative energy flux (forward cascade) is present globally. Finally, the energy analysis shows that the energy cascade is highly dependent on the rotation of the small-scale structure as well as their translational motion.

• Received 24 April 2019

DOI:https://doi.org/10.1103/PhysRevFluids.4.104610