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Numerical Investigation on the Early Onset of Natural Convection in a Cavity at Low Rayleigh Numbers
Messaouda BOULMAALI Messaouda BOULMAALIa and Abdelkader KORICHI Abdelkader KORICHIb
aGraduate Student, Faculty of Technology, Laboratory of Mechanics, Physics and Mathematical Modelling (LMP2M), University of Medea 26000, Algeria.
bProfessor, Faculty of Technology, Laboratory of Mechanics, Physics and Mathematical Modelling (LMP2M), University of Medea 26000, Algeria
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Abstract:
This study employs computational methods to investigate the early onset of natural convection in a square cavity, focusing on the dynamics at low Rayleigh numbers using the open-source OpenFOAM software. Through detailed analysis of streamlines and Nusselt numbers, the research identifies a gradual initiation of flow, characterised by evolving patterns and complex dynamics. The study examines the influence of the Rayleigh number (Ra) on flow behaviour, revealing that the time required for perturbation decreases as Ra increases. The steady-state flow is obtained at approximately nondimensional time This value is reduced to 18 for Ra = 1000. At very low Rayleigh number (Ra<250), convection is negligible ( . As Ra increases, the convection begins to play a role and becomes noticeable for Ra>800 ( ), reaching a value at Ra=1000. These findings offer valuable insights with practical applications in thermal management and fluid dynamics.
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Keywords: Natural convection in a cavity, low Rayleigh numbers, onset of convection, early stages.
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©
2026
CSME , ISSN 0257-9731
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