The effect of the spanwise discretisation on numerical calculations of the turbulent flow around a circular cylinder is systematically assessed at a subcritical Reynolds number of 10000 in the frame of three-dimensional large-eddy simulation. The eddy-viscosity k-equation subgrid scale model is implemented to evaluate unsteady turbulent flow field. Large-eddy simulation is known to be a reliabl...

This report extends a recent method that calculates an ensemble of solutions of the Navier-Stokes equations efficiently to higher Reynolds number flows. To do so herein we develop and analyze two ensemble eddy viscosity models that do not obviate the good algorithmic properties of the ensemble method. The combined approach of ensemble time stepping and ensemble eddy viscosity modelling has othe...

The 1877 assumption/conjecture of Boussinesq is that turbulent fluctuations have a dissipative effect on the mean flow. The eddy viscosity hypothesis is that this dissipative effect can be modelled by a turbulent viscosity term. Many computational and experimental data sets have shown that the eddy viscosity hypothesis is not generally correct. The inverse cascade of energy to larger scales in ...

A previous paper by Cimarelli et al. [“General formalism for a reduced description and modelling of momentum energy transfer in turbulence,” J. Fluid Mech. 866, 865–896 (2019)] has shown that every decomposition turbulent stresses is naturally approximated general form tensorial eddy viscosity based on velocity increments. The generality the such it can also be used to give subgrid scalar fluxe...

The goal of this study is to compare the performances of the ensemble Kalman filter and a reduced-rank extended Kalman filter when applied to different dynamic regimes. Data assimilation experiments are performed using an eddy-resolving quasi-geostrophic model of the winddriven ocean circulation. By changing eddy viscosity, this model exhibits two qualitatively distinct behaviors: strongly chao...

Large eddy simulations in a wall bounded domain are conducted in order to study the kinematic structure of premixed turbulent flame. The linear model presents a prospect of isolating the effects of each of the physical mechanisms that underly turbulent combustion. In the present study, we investigate the flame structure in the absence of thermodyamic effects such as heat release using this mode...