Analysis of coherence in turbulent stratified wakes using spectral proper orthogonal decomposition

Modelling Velocity Structures In Turbulent Floods Using Proper Orthogonal Decomposition

There are various techniques available to model the turbulence structure. Turbulence of incompressible water flow (without sediment) can be modelled completely using the Navier-Stokes equations. However for even a small part of a river channel, the size of the problem is many orders of magnitude larger than even the world’s largest super-computers can handle. This means that other techniques ar...

Reynolds number effects in stratified turbulent wakes

We report large-eddy simulations of the turbulent wake of a towed-sphere of diameter D at speed U in a linearly stratified Boussinesq fluid with buoyancy frequency N . These simulations are performed using a spectral-multidomain-penalty-method-based incompressible Navier-Stokes solver for Re ≡ UD/ν ∈ {5 × 10, 10, 4 × 10} and Fr ≡ 2U/(ND) ∈ {4, 16, 64}. Increasingly richer turbulent fine structu...

Proper Orthogonal Decomposition Analysis of a Turbulent Swirling Self-Excited Premixed Flame

Models for turbulent plane Couette flow using the proper orthogonal decomposition

We model turbulent plane Couette flow ~PCF! by expanding the velocity field as a sum of optimal modes calculated via the proper orthogonal decomposition from numerical data. Ordinary differential equations are obtained by Galerkin projection of the Navier–Stokes equations onto these modes. For a minimal truncation including only the most energetic modes having no streamwise variation, we show u...

Artificial viscosity proper orthogonal decomposition

We introduce improved reduced-order models for turbulent flows. These models are inspired from successful methodologies used in large eddy simulation, such as artificial viscosity, applied to standardmodels created by proper orthogonal decomposition of flows coupled with Galerkin projection. As a first step in the analysis and testing of our new methodology, we use the Burgers equation with a s...