Monotonically integrated large eddy simulation of free shear flows

With a view to ensure that proper interaction between resolvable or grid scale and subgrid scale (SGS) motions are mimicked, it is vital to determine the necessary physics that must be built into the SGS models, In ordinary large eddy simulation (LES) approaches, models are introduced for closure in the low pass filtered Navier-Stokes equations (NSEs), which are the ones solved numerically. A promising LES approach is monotonically integrated LES (MILES), which involves solving the unfiltered NSE using high-resolution monotone algorithms; in this approach, implicit SGS models, provided by intrinsic nonlinear high-frequency filters built into the convection discretization, are coupled naturally to the resolvable scales of the flow. Formal properties of the effectual SGS modeling using MILES are documented using databases of simulated homogeneous turbulence and transitional freejets; mathematical and physical aspects of (implicit) SGS modeling through the use of nonlinear flux limiters are addressed in this context. Comparison of MILES and other conventional LES models applied to free shear hows are presented to confirm that the concept of LES is virtually independent of the SGS model if the resolution is fine enough to ensure that the cutoff wave number lies in the inertial subrange, provided that the LES model can adequately channel kinetic energy out of the resolved scales near the cutoff wave number, to prevent spurious energy buildup and aliasing.