Interaction of natural convection and surface radiation in hexagonal enclosure
A 2-D Numerical analysis has been carried out for laminar natural convection and its interaction with surface radiation. The governing equations for fluid flow and heat transfer are solved numerically. The SIMPLE algorithm is used for pressure-velocity coupling. Boussinesq approximation is used to incorporate the buoyancy effect. A thorough grid sensitivity analysis has been carried out to obtain grid independent solution of the variables. The results that are obtained from the present model is compared with benchmark results and found to be in good agreement. The results are presented in terms of isotherms, stream functions and velocity vectors for a range of Rayleigh number (Ra) from 103 to 106. It has been observed that as Ra increases, the strength of natural convection increases and in turn leads to enhancement in the heat transfer from the enclosure. It has also found from the study that there is marked influence of surface radiation on natural convection flow and heat transfer from the enclosure. For the case of Ra=105 it can be seen that the magnitude of maximum velocity for pure natural convection is 0.0351 m/s and for the interaction of natural convection with surface radiation is 0.0376 m/s. Surface radiation has a strong influence on natural convection that can be observed from the stream function contour where the strength of flow is increased. The variation of Nusselt number with Ra have been plotted for different cases.