Two-dimensional velocity-vorticity based LES for the solution of natural convection in a differentially heated enclosure by wavelet transform based BEM and FEM

Jure Ravnik (Author), Leopold Škerget (Author), Matjaž Hriberšek (Author)

Abstract

A wavelet transform based boundary element method (BEM) numerical scheme is proposed for the solution of the kinematics equation of the velocity-vorticityformulation of Navier-Stokes equations. FEM is used to solve the kinetics equations. The proposed numerical approach is used to perform two-dimensional vorticity transfer based large eddy simulation on grids with 105 nodes. Turbulent natural convection in a differentially heated enclosure of aspect ratio 4 for Rayleigh number values Ra=107-109 is simulated. Unstable boundary layer leads to the formation of eddies in the downstream parts of both vertical walls. At the lowest Rayleigh number value an oscillatory flow regime is observed, while the flow becomes increasingly irregular, non-repeating, unsymmetric and chaotic at higher Rayleigh number values. The transition to turbulence is studied with time series plots, temperature-vorticity phase diagrams and with power spectra. The enclosure is found to be only partially turbulent, what is qualitatively shown with second order statistics-Reynolds stresses, turbulent kinetic energy, turbulent heat fluxes and temperature variance. Heat transfer is studied via the average Nusselt number value, its time series and its relationship to the Rayleigh number value.

Keywords

numerično modeliranje;metoda končnih elementov;diskretna valčna transformacija;hitrostno-vrtinčna formulacija;naravna konvekcija;numerical modelling;boundary element method;discrete wavelet transform;large eddy simulation;velocity-vertocity formulation;natural convection;

Data

Language:	English
Year of publishing:	2006
Typology:	1.01 - Original Scientific Article
Organization:	UM FS - Faculty of Mechanical Engineering
UDC:	532.7:519.61/.64
COBISS:	10549782
ISSN:	0955-7997
Views:	1982
Downloads:	71
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary keywords:	numerično modeliranje;metoda končnih elementov;diskretna valčna transformacija;hitrostno-vrtinčna formulacija;naravna konvekcija;
URN:	URN:SI:UM:
Pages:	str. 671-686
Volume:	ǂVol. ǂ30
Issue:	ǂiss. ǂ8
Chronology:	August 2006
ID:	8717103