Fernando De Lai - Academia.edu (original) (raw)
Uploads
Papers by Fernando De Lai
ASME/JSME 2011 8th Thermal Engineering Joint Conference, 2011
ABSTRACT In this study, the natural convection inside a fluid filled enclosure containing several... more ABSTRACT In this study, the natural convection inside a fluid filled enclosure containing several solid obstructions and heated from the side is simulated numerically as to determine the effects of the solid thermal conductivity and volume-fraction. The solid obstructions are conducting, disconnected square blocks, uniformly distributed inside the enclosure. The mathematical model follows a continuum approach, with balance equations of mass, momentum and energy presented for each one of the constituents (i.e., fluid and solid) inside the enclosure. The equations are then solved numerically via the finite-volume method. The effects of varying the solid-fluid thermal conductivity ratio (K), the fluid volume-fraction or porosity (φ), the number of solid blocks (N) and the heating strength (represented by the Rayleigh number, Ra) on the natural convection process inside the enclosure are investigated parametrically. The Nusselt number based on the surface-averaged heat transfer coefficient along the heated wall is chosen to characterize the convection strength inside the enclosure. The results indicate a competing effect caused by the proximity of the solid blocks to the heated and cooled walls of the enclosures, vis-à-vis hindering the boundary layer growth, hence reducing the heat transfer effectiveness, and at the same time enhancing the heat transfer when K is large. An analytical estimate of the minimum number of blocks beyond which the convection hindrance becomes predominant is presented and validated by the numerical results.
Heat Transfer Engineering, 2013
In this paper, hydrodynamic and thermal behaviors of fluid inside a wavy walled enclosure are inv... more In this paper, hydrodynamic and thermal behaviors of fluid inside a wavy walled enclosure are investigated. The enclosure consists of two wavy and two straight walls. The top and the bottom walls are wavy and kept isothermal. Two vertical straight walls (right and left) are considered adiabatic. The integral forms of the governing equations are solved numerically using Finite Volume method. Computational domains are divided into finite numbers of body fitted control volumes with collocated variable arrangement. Results are presented in the form of local and global Nusselt number distributions for a selected range of Grashof number (10 3 -10 7 ). Streamlines and isothermal lines are also presented for four different values (0.0, 0.05, 0.1, 0.15) of amplitude-wavelength ratios (= α/λ) and for a fluid having Prandtl number 1.0. Throughout this study, aspect ratio (= δ/λ) is kept equal to 0.40. Calculated results for Nusselt number are compared with the available references. 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.
ASME/JSME 2011 8th Thermal Engineering Joint Conference, 2011
ABSTRACT In this study, the natural convection inside a fluid filled enclosure containing several... more ABSTRACT In this study, the natural convection inside a fluid filled enclosure containing several solid obstructions and heated from the side is simulated numerically as to determine the effects of the solid thermal conductivity and volume-fraction. The solid obstructions are conducting, disconnected square blocks, uniformly distributed inside the enclosure. The mathematical model follows a continuum approach, with balance equations of mass, momentum and energy presented for each one of the constituents (i.e., fluid and solid) inside the enclosure. The equations are then solved numerically via the finite-volume method. The effects of varying the solid-fluid thermal conductivity ratio (K), the fluid volume-fraction or porosity (φ), the number of solid blocks (N) and the heating strength (represented by the Rayleigh number, Ra) on the natural convection process inside the enclosure are investigated parametrically. The Nusselt number based on the surface-averaged heat transfer coefficient along the heated wall is chosen to characterize the convection strength inside the enclosure. The results indicate a competing effect caused by the proximity of the solid blocks to the heated and cooled walls of the enclosures, vis-à-vis hindering the boundary layer growth, hence reducing the heat transfer effectiveness, and at the same time enhancing the heat transfer when K is large. An analytical estimate of the minimum number of blocks beyond which the convection hindrance becomes predominant is presented and validated by the numerical results.
Heat Transfer Engineering, 2013
In this paper, hydrodynamic and thermal behaviors of fluid inside a wavy walled enclosure are inv... more In this paper, hydrodynamic and thermal behaviors of fluid inside a wavy walled enclosure are investigated. The enclosure consists of two wavy and two straight walls. The top and the bottom walls are wavy and kept isothermal. Two vertical straight walls (right and left) are considered adiabatic. The integral forms of the governing equations are solved numerically using Finite Volume method. Computational domains are divided into finite numbers of body fitted control volumes with collocated variable arrangement. Results are presented in the form of local and global Nusselt number distributions for a selected range of Grashof number (10 3 -10 7 ). Streamlines and isothermal lines are also presented for four different values (0.0, 0.05, 0.1, 0.15) of amplitude-wavelength ratios (= α/λ) and for a fluid having Prandtl number 1.0. Throughout this study, aspect ratio (= δ/λ) is kept equal to 0.40. Calculated results for Nusselt number are compared with the available references. 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.