Fully-resolved numerical simulations of the turbulent flow and particle deposition in a cubical cavity with two pairs of differentially heated opposed walls at Rayleigh number 3.6 × 109

Identifier:  imarina:9287664

Handle: https://hdl.handle.net/20.500.11797/imarina9287664

Authors:  Lavrinenko, Akim; Gisbert, Ferran; Pallares, Jordi; Fabregat, Alexandre

Abstract:
The turbulent dispersion and deposition of airborne solid particles is studied by means of fully-resolved numerical simulations. The computational domain, consisting in a cubical cavity with differentially heated opposed walls filled with air, reproduces the experimental conditions of measurements previously reported in the literature. The computational model assumes that each solid spherical particle trajectory is governed by the balance between hydrodynamic drag, buoyancy, lift, thermophoresis and Brownian forces. The dominant terms responsible for particle deposition mostly depend on the particle size, the solid–gas density ratio and the hydrodynamics within the thermal and momentum boundary layers near the solid surfaces. The present results suggest that previous correlations for the wall-averaged Nusselt number as a function of Rayleigh number over the range between 107 and 5.4×108 can be extended up to Rayleigh number 3.6×109. Also, numerical predictions of the particle deposition rates on thermally active surfaces are in good agreement with both experimental data and analytical boundary layer solutions for particle sizes ranging between 0.1 μm and 2.5 μm in diameter. These particle sizes allows to study different particle deposition regimes varying from that controlled by thermophoresis (0.1 μm) to that dominated by gravitational forces (2.5 μm).