No abstract

A numerical investigation is performed to analyze the steady natural convection phenomena of air in an enclosure with partial active side walls. A partition is attached to the hot wall for different active locations in order to study the effect of the partition position on the heat transfer. Firstly, the coupled equations of continuity, momentum and energy are solved by a finite volume method. The SIMPLE algorithm is used to solve iteratively the pressure velocities coupling. Secondly and based on the obtained dimensionless velocity and temperature values, the distributions of the local entropy generation due to heat transfer and fluid friction, and the local entropy generation are determined for different parameters. The results are presented graphically in the form of streamlines, isotherms and also with average Nusselt numbers. three different configurations of active region arrangement are considered in this study while the partition length has been changed. In order to identify the optimum location of the partition for better heat transfer, the effect of entropy generation has been studied. The heat transfer rate is found to decrease with an increase in the partitions length especially for l=L/2 Thus, the maximum average Nusselt number occurs for middle-middle arrangement while the minimum one occurs for the bottom-bottom arrangement.

In this paper, the natural convection flow in a cavity heated differentially with a partition placed in the middle of the hot wall is numerically simulated. The aspect ratio of the geometry, Prandtl number are fixed at 0.24, 6.64, respectively, for different partitions lengths; however the Rayleigh number values were ranging from 106 to 3.77 × 109 in order to observe the transition regime. The fluid flow and the heat transfer described in terms of continuity, linear momentum and energy equations were predicted by using the finite volume method. To approach the physical reality experience, calculations were performed in a cavity with the same size and same priority of the fluid with an average temperature Tm imposed on the cooled wall, also another simulation with an average temperature Tm imposed on the horizontal wall.Time evolution, isotherms and mean Nusselt number are presented for all investigated values. Representative results illustrating the effects of the partition length for the heat transfer and the thermal boundary layer are also reported and discussed. The results indicate that the flow and heat transfer properties are altered by the presence of the partition, especially in the initial stage. In a certain sense, the partition blocks the flow and forces it to come off the hot wall. Since the partition parameters are critical for the transient natural convection flow in the cavity, different partition lengths on the warm wall have been studied.

The main objective of this work is to study numerically the unsteady natural convection phenomena in water filled rectangular enclosure with hot partitioned wall. The fluid flow and the heat transfer described in terms of continuity, linear momentum and energy equations were predicted by using the finite volume method. Streamlines, isotherms and local Nusselt number time evolution are presented for all investigated values. The aspect ratio of the geometry, Prandtl number are fixed at 0.24, 6.64, respectively, for different partitions lengths; however the Rayleigh number values were ranging from 106 to 3,77x109 in order to observe the transition regime. Representative results illustrating the effects of the partition length for the heat transfer and the thermal boundary layer are also reported and discussed. The obtained results show that the presence of the partition on the hot wall affects both heat transfer and fluid flow. It was found that the average Nusselt number increases with increase in the Rayleigh number. Also, as the dimensionless partition length increases, the flow speed within the partitioned enclosure decreases. Moreover, the features of the unsteady flow induced by the presence of partitions are characterized and the mechanisms responsible for the unsteadiness are discussed.