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This study presents an investigation into forced convection within laminar fluid flow through a configuration consisting of two heated cubic obstacles with circular perforations, arranged in a staggered pattern on a horizontal plate. The research addresses the critical challenge of enhancing heat transfer in such configurations by examining the influence of variations in streamwise distance (L) and spanwise distance (m) on thermal performance. Employing the finite-volume method, simulations were conducted across a range of parameters: L from 1 to 2 times the obstacle height (H), m from 1/2 to 2 times H, Reynolds numbers (Re) between 102 and 3 × 102, and perforation diameter ratios (D/H) of 0.42 and 0.88. The findings reveal that the Nusselt number (Nu) exhibits significant variation with changes in L/H for solid obstacles, while this effect diminishes for perforated obstacles, particularly at a D/H ratio of 0.88. For the first obstacle, optimal heat transfer is achieved with a streamwise distance equal to H for solid obstacles, whereas no notable differences are observed between the arrangements of perforated models. Notably, perforated obstacles with the maximum D/H ratio exhibit a Nu increase of up to 30% compared to solid obstacles. For the second obstacle, the optimal configuration across all types involves a streamwise distance of H and a spanwise distance of 2H, leading to a 37.4% increase in Nu for large-diameter perforated obstacles compared to solid ones. Overall, the staggered arrangement of perforated obstacles outperforms the tandem arrangement, enhancing heat transfer by up to 43.52% for the first obstacle, 109% for the second obstacle, and 48% for the entire system. This study introduces novel insights into the impact of perforation and obstacle arrangement on heat transfer, demonstrating that staggered arrangements and larger perforation diameters significantly enhance heat transfer compared to solid obstacles, thereby advancing the understanding of convective heat transfer in such setups. [ABSTRACT FROM AUTHOR]

Air plate solar collectors provide a sustainable and efficient solution for building heating. The absorber plate collects solar radiation and converts it into heat. Atmospheric air is then circulated through the collector plate with perforated baffles by forced convection. The heated air is then directed through ducts into the building's heating system. By significantly reducing reliance on fossil fuels for building heating, these collectors contribute to a lower life-cycle carbon footprint for buildings compared to conventional heating systems. While flat-plate solar collectors are widely used for renewable energy generation, their efficiency is frequently limited by the airflow path and the heat transfer efficiency within the collector. This study aims to quantify the impact of longitudinal, transverse, and perforated baffles with different hole diameters on the heat transfer characteristics and to identify the optimal design for maximizing thermal efficiency. This study also aims to integrate solar air collector in a conventional building and help reduce the overall energy demand of buildings and their associated carbon emissions. A three-dimensional numerical investigation was carried out on a flat-plate solar collector equipped with perforated transverse baffles with varying hole diameter and thickness. The results from the study predicted that perforated baffles with two holes with a diameter of 15 mm provided a maximum Nu of 79.56 and a pressure drop of 459 Pa for a Re of 8500. [ABSTRACT FROM AUTHOR]

Cavitating Venturis are simple apparatus used as a flow meter over a broad range of mass-flow rates. The main objective of this work is to introduce obstacles in small-sized cavitating Venturis in order to increase their capacity by raising the critical pressure, i.e. widens the phase of the cavitating mode. Four configurations have been tested depending on the location of these obstacles. This study focused on investigating the numerical performance of cavitating Venturis with different downstream pressures by employing the k-ω SST turbulence model and the Rayleigh-Plesset equation for modeling cavitation. The governing equations were solved using the finite volume method, employing the Rhie and Chow pressure-velocity coupling scheme. The results showed the void fraction and streamlines contours obtained on the symmetry plane. The mass-flow ratio was presented for all configurations and different pressure ratios. The study showed that the cavitating Venturis equipped with obstacles extend the phase of choked mode from 10.71% to 21.42% and that the best configuration correspond to the case where the obstacles are placed in the converging section. [ABSTRACT FROM AUTHOR]

In this piece, the impact of an obstacle's upstream edge inclination in a rectangular channel is investigated. The main purpose of this study is to give a better understanding of this associated phenomenon by reflecting more accurately the different cooling techniques and to get as close as possible to real conditions of use. This study is based on the laws of conservation of mass, momentum, and energy, the equations are given in the case of the 2-D flow of an incompressible Newtonian fluid, depending on the variables primitives given below. During the study, we used the FLUENT computer code, as well as its GAMBIT mesh generator several times, which allowed us to become more familiar with numerical simulation. The purpose of our numerical research is to clarify physical phenomena that are described by theory without using more expensive experimentation. [ABSTRACT FROM AUTHOR]

The study is conducted around a heat exchanger, its channel is horizontal rectangular, its upper wall is isothermal, while its lower wall is thermally insulated, containing extended surfaces in the form of triangular obstacles attached in a staggered manner periodically. Four models of the channel with various roughnesses were compared in this study. Square, triangular Type 1, triangular Type 2, and triangular Type 3 roughnesses, which are positioned on the hot top part of the channel (absorber), downstream of the last obstacle, are examined to promote heat transfer between the absorber and the heat transfer fluid. The case of triangular roughness (Type 3) is the optimal case in terms of improved heat transfer. Moreover, it shows a significant decrease in terms of friction values. [ABSTRACT FROM AUTHOR]

The present work aims to investigate the recirculation and incipient mixing zones in a channel flow supplied with obstacles. The main objective is to develop a new technique to control these recirculation zones by setting a variable roughness. For the purpose of varying that roughness, 4 small bars of heights 0.25H, 0.5H, 0.75H and H were placed downstream of the obstacle; H is the height of the obstacle. For this, a three-dimensional numerical approach was carried out using the ANSYS CFX computer code. In addition, the governing equations were solved using the finite volume method. The K-γ shear-stress transport (SST) turbulence model was utilized to model the turbulent stresses. In the end, we presented the time-averaged simulation results of the contours of the current lines (3D time-averaged streamlines, trace-lines), three components of the velocities: (velocity u contour), (velocity v contour) and (velocity w contour), trace-lines, stream ribbons and mean Q-criterion iso-surface. [ABSTRACT FROM AUTHOR]