Abstract

Natural convection of gas flow (air) confined within an enclosed square-section cavity is investigated numerically using the lattice Boltzmann method (LBM). The right (left) side of the enclosure is partially heated (cooled) by a hot (cold) chip, while the left (right) one is completely kept at cold (hot) temperature. However, the horizontal walls and vertical parts near the chip are kept adiabatic. The buoyancy effect induced by the gravity acceleration, related to the convection force, is evaluated through the Rayleigh number in the range of 1 0 3 − 1 0 6 (laminar regime). The wall heating-ratio effect on the flow properties such as temperature and velocity profiles was examined. The heat transfer is analyzed through the Nusselt number for different chip lengths. Results show that the wall heat ratio has an interesting effect on the flow behavior. Results show good agreement with those of full natural convection in the literature, experimental, and simulation data.

Highlights

  • Modern framework-based systems including gas flows at various sizes of uses are in growth development

  • Good agreement is observed between the present simulation results and those obtained by Lai and Yang [12], on the one hand, and with the experimental data obtained by Krane and Jessee [18], on the other hand

  • According to the Rayleigh number, different hot chip lengths are compared with those of cold chip based on the profiles of temperature, velocity components, and Nusselt number

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Summary

Introduction

Modern framework-based systems including gas flows at various sizes of uses are in growth development. Using the LBM models, the simulation of incompressible flows and heat transfer problems can be typically carried out Both governing equations of density and temperature distribution functions are solved according to a specified arrangement in lattices. At the micron level, a kinetic-based approach is needed to capture nonequilibrium effects described by Boltzmann equation [9] In this context, Tang et al [10] proposed a thermal boundary condition for TLBM. The thermal and hydrodynamic behaviors of flow are modeled by means of thermal Lattice Boltzmann (TLBM) [2] In this model, the temperature and density field are modeled independently using two distribution functions which allow us to simulate the heat transfer convection processes [3]. Note that the criterion for switching between the laminar (Ra ≲ 106) and turbulent regimes (Ra > 106) are given by [16]

Problem Statement
Lattice Boltzmann Method
Results and Discussion
Conclusion

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