Numerical investigation of laminar and turbulent mixed convection in a shallow water-filled enclosure by various turbulence methods

Abstract

In this study, we first modeled laminar mixed convection inside rectangular enclosure with moving wall and ‘aspect ratio’ = 10 and then the results were compared with other investigators. After showing verity of results, we continued our investigation with turbulent flow using standard , RNG and RSM models for Richardson numbers 0.1 to 10 and Ra = 6 × 109. The results showed that the turbulence intensity depends on the position. For example, in vertical walls and boundary layer, the flow was laminar and flow in center of enclosure was turbulent. In addition, the results indicated that as the Richardson number increased, the velocity changed happen more frequently in the vertical direction and fluctuations were seen more and more. Another conclusion to be drawn was that at natural convections, the Reynolds stresses curves gone under too many fluctuations all of which was the great impact of the ‘buoyancy force’ and the properties of ‘natural convection’ within this Richardson number. The last and foremost deduction was that at the ‘turbulence flow’, ‘heat transfer’ was generally greater than laminar flow and that was due to high level of mixing at the first. Key words: Reynolds stress, Richardson number, Boussinesq approximation, mixed convection heat transfer, turbulent intensity.