Journal of Advanced Research in Fluid Mechanics and Thermal Sciences51, Issue 1 (2018) 42-52 42 Journal of Advanced Research in Fluid Mechanics and Thermal Sciences Journal homepage: www.akademiabaru.com/arfmts.html ISSN: 2289-7879 Numerical study three-dimensional of mixed convection in a cavity: Influence of Reynolds and Grashof numbers Razik Benderradji 1,2,* , Hamza Gouidmi 2 , DjedidTaloub 1,2 , Abdelhadi Beghidja 2 1 Department of Physics, Faculty of Science, University Med Boudiaf M’sila, Algeria 2 Laboratory of Renewable Energy and Sustainable Development (LREDD), University of the Mentouri Brothers, Constantine 1, Algeria ARTICLE INFO ABSTRACT Article history: Received 20 July 2018 Received in revised form 12 August 2018 Accepted 1 November 2018 Available online 6 November 2018 In this work, we present a numerical study of mixed convection heat exchange in a cubic cavity of a laminar three-dimensional (3D) incompressible flow. This study predicted the behavior of the flow structure between Multi clear structure dominated by natural convection when the Reynolds number is small, and a Multi clear structure dominated by forced convection when the Reynolds number is high. First, we fix the Grashof number for the variable Reynolds number. Second, we vary the number of Grashof for which the Reynolds number is kept fixed. The results obtained give a clear comparison with those found in the literature it examines and explains the thermal and dynamic characteristics of the flow. Keywords: mixed convection, cavity,multi clear structure, number of Grashof and Reynolds Copyright © 2018 PENERBIT AKADEMIA BARU - All rights reserved 1.Introduction For many years, laminar and turbulent flows of closed cavity natural convection have been the subject of numerous numerical and experimental studies, such as the work of Ogut [1], Baracoset al., [2], Dixit et al., [3], Saatiet al., [4], and those of mixed convection such as the work of Haigermoseret al., [5], Med Tofiqui Islam et al [6], SumonSahaet al., [7], Krishnakumaret al., [8], Rahman et al., [9], Bouaraouret al., [10]. They studied rectangular cavities. On the one hand these studies were carried out under conditions where the Reynolds number is varied and on the other hand, it is constant. It is the same for the number of Grashof but in the opposite direction. The interest in this type of flow comes from the fact that, for many industrial applications, in particular, the compressor (and the turbine (rotor-stator), the analysis of the phenomena involves forces of stability thrusts which, coupling with a confining effect, give rise to complex and varied flows. This complexity is accentuated by the generally unsteady character. All these motions of the fluids motivated fundamental studies aiming to better apprehend the couplings between the dynamics and the thermal of such systems, the interactions between the moving fluid and the walls, the influence of the geometry or the boundary conditions (with imposed temperature conditions or imposed heat fluxes), the appearance and development of vortex instabilities. Turbulence is generally described as a disordered flow in time and space. It is unpredictable in the sense that a small initial disturbance at a given instant Penerbit Akademia Baru Open Access