Study of thermal comfort: numerical simulation in a closed cavity using the lattice Boltzmann method
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Study of thermal comfort: numerical simulation in a closed cavity using the lattice Boltzmann method Nabil Himrane1 · Djamel Eddine Ameziani2 · Lyes Nasseri2 Received: 14 October 2019 / Accepted: 25 March 2020 © Springer Nature Switzerland AG 2020
Abstract In this work, a study on thermal comfort in building is presented as it has great interest given its impact on the quality of indoor environments. The thermal comfort depends on several parameters such as air temperature and velocity, relative humidity and so on. With this in mind, numerical investigation is carried out on natural convection induced by temperature gradient between the lower and upper walls in a square enclosure filled with a Newtonian fluid. To approach the real case of underfloor heating subject to real weather conditions, periodic time varying temperature is imposed on the lower wall of the enclosure. The mathematical problem has been formulated by considering the Boussinesq’s approximation, and the resulted governing equations are solved using the Lattice Boltzmann Method. The study has been carried out for Rayleigh numbers in the range 103 ≤ Ra ≤ 106, while Prandtl number and aspect ratio are kept constant at 0.71 and 1, respectively. The results obtained show that the flow’s behaviour is strongly dependent on the values of Rayleigh numbers and heating amplitude. The temporal evolution of the spatially averaged Nusselt number indicate that the transfer regime is periodic for low values of Ra and switches to a perturbed unsteady flow for hight values. Keywords Component · Thermal comfort · Periodic heating · Rayleigh–Bénard convection · Lattice Boltzmann method
1 Introduction A large amount of energy is used for the space heating/ cooling of buildings. The heating/cooling energy consumption depends on the characteristics of building (exterior conditions, physical properties, energy efficiency of inner sub-systems and occupancy). Thermal analysis is necessary to assess the building energy performance. Furthermore, the analysis permits to predict thermal responses and calculate heating/cooling loads of buildings. It is also helpful to achieve the energy efficiency and the thermal comfort of buildings. Several numerical and experimental studies have been carried out on thermal comfort in the building [1–3].The lattice Boltzmann method (LBM) that has been rapidly progressing in
developing new models and applications in many fields has attracted much attention and interest [4–7]. Unlike traditional methods which solve macroscopic equations, the LBM simulates fluid flow based on microscopic models or mesoscopic kinetic equations. This intrinsic feature enables LBM to incorporate easily a multitude of essential physics at microscopic or mesoscopic level [8]. The Rayleigh–Bénard convection has been extensively studied experimentally and theoretically because of its frequent occurrence in various domains. A full account of the linearized theory is given in Chandrasekhar [9] and Drazin and Reid [10]. Osman [11] study numerically the laminar Rayleig
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