Proper orthogonal decomposition analysis of coherent structures in a transient buoyant jet
Authors:
- X. ZhouXZX. Zhou
- D. L. HittDHD. L. Hitt
- 1 August 2004
- journal article
- Published by Taylor & Francis in Journal of Turbulence
- Vol. 5
Abstract
The spatial evolution of a circular buoyant jet at moderate Reynolds number (Re = 103) and density ratio (ρ* = 2) has been investigated using large-eddy simulation (LES). The Smagorinsky subgrid-scale model is used for the unresolved small-scale turbulence. Dynamic puffing phenomena is observed and corresponds to the formation of large-scale vortex structures near the plume base with an axisymmetric mode of instability. These toroidal vortical structures break down into smaller, disorganized eddies with increasing distance downstream. Two-point correlation variances of temperature and velocities generated from LES are analysed using the proper orthogonal decomposition (POD) method. The POD analysis yields a set of numerical eigenfunctions which provide a reduced-order description of the flow. The energy of the flow is found to be well represented by a finite number of eigenmodes. For example, our results indicate that the first 20 modes capture over 70% of the total energy in the transitional region. Furt...Keywords
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