We perform a direct numerical simulation (DNS) of forced homogeneous isotropic turbulence with a passive scalar that is forced by mean gradient. The DNS data are used to study the properties of subgrid-scale flux of a passive scalar in the framework of large eddy simulation (LES), such as alignment trends between the flux, resolved, and subgrid-scale flow structures. It is shown that the direct...

Subgrid effects can have a strong influence on flow and transport in oil reservoirs. In this work, a new model for the representation of subgrid terms is introduced and applied to two-phase reservoir flows. The model entails a generalized convection-diffusion treatment of the saturation equation as well as an extended representation for total mobility in the pressure equation. Motivation for th...

Articles you may be interested in Multifractal subgrid-scale modeling within a variational multiscale method for large-eddy simulation of passive-scalar mixing in turbulent flow at low and high Schmidt numbers The physics of energy transfer toward improved subgrid-scale models A hybrid subgrid-scale model constrained by Reynolds stress A dynamic subgrid-scale eddy viscosity model with a global ...

The coherent/incoherent decomposition of the subgrid-scale stresses based on the wavelet de-noising procedure is exploited in the framework of large-eddy simulation of turbulence. Dynamic a-priori tests based on the perfect modeling approach are performed for decaying isotropic turbulence. The theoretical performances of deterministic/stochastic subgrid-scale models are evaluated during the sim...

Subgrid-scale variability is one of the main reasons why parameterizations are needed in largescale models. Although some parameterizations started to address the issue of subgrid variability by introducing a subgrid probability distribution function for relevant quantities, the spatial structure has been typically ignored and thus the subgrid-scale interactions cannot be accounted for physical...

A stochastic variational multiscale method with explicit subgrid modeling is provided for solution of stochastic elliptic equations that arise while modeling diffusion in heterogeneous random media [1]. The exact solution of the governing equations is split into two components: a coarse-scale solution and a subgrid solution. A localized computational model for the subgrid solution is derived. T...

Models for transport in heterogeneous subsurface formations usually require some type of treatment for subgrid effects. In this work, a generalized nonlinear convection-diffusion model for subgrid transport in two-dimensional systems is developed and applied. The model, although somewhat heuristic, is motivated by previous findings within both the stochastic and the deterministic frameworks. Th...

Numerical simulations of the atmosphere are routinely carried out on various scales for purposes ranging from weather forecasts for local areas a few hours ahead to forecasts of climate change over periods of hundreds of years. Almost without exception, these forecasts are made with space/time-averaged versions of the governing Navier-Stokes equations and laws of thermodynamics, together with a...

In this paper we present an alternative formalism for large-eddy simulation that avoids the problems arising from filtering the governing equations. In particular, we instead propose to filter solutions leading to the ability to directly model subgrid-scale primitive variables; i.e., model physics rather than statistics. We then demonstrate construction of subgrid-scale models of scalar quantit...