The problem of steady, laminar and incompressible NATURAL CONVECTION flow in an octagonalenclosure was studied. In this investigation, two horizontal walls were maintained at a constant hightemperature, two vertical walls were kept at a constant low temperature and all inclined walls wereconsidered adiabatic. The enclosure was assumed to be filled with a Bousinessq fluid. The studyincludes computations for different Prandtl numbers Pr such as 0.71, 7, 20 and 50 whereas the Rayleighnumber Ra was varied from 103 to 106. The pressure-velocity form of Navier-Stokes equations andenergy equation was used to represent the mass, momentum and energy conservations of the fluidmedium in the enclosure. The governing equations and boundary conditions were converted todimentionless form and solved numerically by penalty finite element method with discretization bytriangular mesh elements. Flow and heat transfer characteristics were presented in terms of streamlines, isotherms and average Nusselt number Nu. Results showed that the effect of Ra on the CONVECTION heattransfer phenomenon inside the enclosure was significant for all values of Pr studied (0.71-50). It wasalso found that, Pr influence NATURAL CONVECTION inside the enclosure at high Ra (Ra > 104).

In this article the NATURAL CONVECTION of nano-fluid water-copper in a square cavity has been studied numerically. The left wall is maintained at high temperature, right wall is maintained at low temperature and the other walls are adiabatic. The numerical model is based on the SIMPLE algorithm is used to solve the equations of continuity, momentum and energy. The effects of pertinent parameters such as the position and length of the baffle, Rayleigh number and solid volume fraction, on the thermal performance of the cavity are examined. The results showed that, the increase of the Rayleigh number and volume fraction of nanoparticle increased the average Nusselt on both hot and cold walls. The results also showed that the average Nusselt numbers on cold wall increased and on hot wall decreased with increase of the baffle length.

The aim of the present numerical study to analyze the conjugate NATURAL CONVECTION heat transfer in a rotating enclosure with finite wall thickness. The enclosure executes a steady counterclockwise an-gular velocity about its longitudinal axis. The staggered grid arrangement together with the Marker and Cell (MAC) method was employed to solve the governing equations…

The storage and disposal of greenhouse gases in underground aquifer reservoirs is a suitable option for the reduction of these gases in the atmosphere. Understanding the concepts and mechanisms involved in the storage process such as NATURAL CONVECTION and their impact on the amount of time required for storage is very important. NATURAL CONVECTION is an effective mechanism to increase the solubility of carbon dioxide in the storage process. In this study, the injection of carbon dioxide (a major component of greenhouse gases) into aquifer has been studied and numerically simulated. The effect of aquifer salinity on the onset of NATURAL CONVECTION phenomena has been studied. To this end, six scenarios revolving around the change of aquifer salt and keeping the other variables involved constant in the process are studied. The results reveal a direct effect of salinity on the activation of NATURAL CONVECTION. Increasing aquifer salinity delays the onset of NATURAL CONVECTION. As a result, the cumulative amount of gas dissolved after the specified time will be less.

In this paper, free CONVECTION in an inclined stepped chamber has been studied. One wall of this enclosure is kept cold and the opposite wall equipped with constant heat source. The remaining walls are maintained adiabatic. There is one adiabatic step on the bottom wall. The aim of the present study is to forecast the effect of Raleigh number, slope of enclosure, step dimension, and heat source position, on the stream field, temperature and heat transfer rate. In this regard, two dimensional equations of mass conservation, linear momentum and energy are solved by applying finite volume method and simple algorithm. Results indicate poor effect of enclosure slope, step height, and position of heat source in small Raleigh numbers, however in large Raleigh numbers significant effects on fluid and rate of heat transfer of enclosure are observed.