Numerical investigation of mixed convection in a lid driven cavity with rotating and fixed cylinder

Abstract

Mixed convection is a prevalent phenomenon that spans from various natural occurrences to numerous industrial applications. Lid driven cavity problem arises as one of the crucial subjects of research in mixed convection processes among industrial applications. In the present study, heat transfer in a lid driven square cavity with a centered rotating or fixed cylinder is examined with different values of Reynolds and Grashof numbers. Main goal of the study is to understand the effect of these parameters on thermo-fluidic flow field inside the cavity and heat transport from hot boundary to cold boundary of the enclosure. Boundary conditions of the cavity are defined so that bottom wall has high temperature, sliding top wall is kept at low temperature while vertical walls are adiabatic. Flow inside the cavity is assumed as laminar and Boussinesq approach is used for momentum calculations. In the study, mainly two different configurations are observed which are cavity with a rotating cylinder and cavity with a fixed cylinder. Thermal boundary condition of the hollow cylinder is defined as isothermal for extended analyses, but for cylinder wall, it is defined as isothermally low temperature or adiabatic in preliminary analyses due to comparison purposes. In order to conduct analyses in range of 100≤Re≤1000 and 100≤Gr≤100000, artificial fluid approach is used so that top wall velocity, viscosity, specific heat and angular velocity of the hollow cylinder is defined by corresponding dimensionless parameters with the help of fixed dimensional parameters such as temperature difference or density. A new nondimensional parameter, COP, is defined to measure efficiency of the lid driven cavity by using division of dimensionless heat transfer to dimensionless work. Dimensionless heat transfer and dimensionless work is calculated by using the ratios between heat transfer or work and baseline values of those outputs which are calculated where for baseline heat transfer, Re=0, for baseline work, Gr=0. It is observed that for thermal boundary condition of cylinder affects heat transfer inside the cavity such that it is higher in isothermal condition of cylinder due to high temperature gradients between cylinder and bottom wall. On the other hand, higher COP is experienced in adiabatic cases due to lower baseline heat transfer compared to isothermal cylinder cases.