Explicit small-scale velocity simulation for high-Re turbulent flows

A new approach, two level simulation (TLS), is developed based on the explicit reconstruction of the small-scale velocity by solving the small-scale governing equations on the domain with reduced dimension representing a collection of one-dimensional lines embedded in the three-dimensional flow domain. A coupled system of equations, that is not based on an eddy-viscosity hypothesis, is derived based on the decomposition of flow variables into the large-scale and the small-scale components without introducing the concept of filtering. Simplified treatment of the small-scale equations is proposed based on neglecting the small-scale advective and dissipative terms in the line orthogonal directions. Fully coupled simulation of the forced isotropic turbulence at Reλ ≈ 65, 114 demonstrates potential benefits and challenges of the TLS approach for high-Re turbulent flows using coarse grids.