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The energy loss through building components resulting in higher energy consumption, thus energy saving has become an essential aspect in design and comfort. This study aims to optimize the thermal insulation of red clay bricks used in the walls of buildings by using a multiscale method. The finite element approach in ABAQUS software has been used to simulate the bricks under different configurations and conditions. Due to cost and time challenges and difficulties in simulation and complex calculations, simplified and applicable equations have been derived to calculate thermal insulation properties. The results show that the paper's brick design has a significant thermal conductivity reduction that could reach more than one-third of the other corresponding studies. The study goes to fill the hollow bricks by the insulation polyurethane foam (PUF) and comparing the results with air hollow bricks. Besides its other advantages, the outcomes reveal that using the PUF has a noticeable desired-influence in thermal insulation when considering the heat transfer by convection and radiation inside the air cavity of bricks. [ABSTRACT FROM AUTHOR]

Numerical investigations are presented for mixed convection problems in a concentric inner sinusoidal cylinder and an outer rotating circular cylinder, which were kept at constant hot and cold temperatures, respectively. The free space between the cylinders and the enclosure walls was filled with a water‐Cu nanofluid. The governing equations are formulated for velocity, pressure, and temperature formulation and are modeled in COMSOL5.2a, a partial differential equation solver based on the Galerkin finite element method. The governing parameters considered are the solid volume fraction, [0, 0.02, 0.04, and 0.06], Re (1, 25, 100, 200, and 300), and Ra (less than 104), and the inner cylinder corrugation frequencies varied from (N = 3, 6, and 9). According to the calculations, the Reynolds number, the Rayleigh number, the nanoparticle volume fraction, and the number of corrugations play an important role of forming the stream and isothermal lines, the local and the average Nusselt number inside the annulus enclosure. The average Nusselt number decreases with increasing Reynolds number and the number of corrugations, while it increases as the Rayleigh number and the volume fraction increase. [ABSTRACT FROM AUTHOR]