{"title":"Mixed Convection in a Vertical Heated Channel: Influence of the Aspect Ratio","authors":"Ameni Mokni , Hatem Mhiri , Georges Le Palec , Philippe Bournot ","country":null,"institution":"","volume":33,"journal":"International Journal of Physical and Mathematical Sciences","pagesStart":628,"pagesEnd":635,"ISSN":"1307-6892","URL":"https:\/\/publications.waset.org\/pdf\/10118","abstract":"In mechanical and environmental engineering, mixed\r\nconvection is a frequently encountered thermal fluid phenomenon\r\nwhich exists in atmospheric environment, urban canopy flows, ocean\r\ncurrents, gas turbines, heat exchangers, and computer chip cooling\r\nsystems etc... . This paper deals with a numerical investigation of\r\nmixed convection in a vertical heated channel. This flow results from\r\nthe mixing of the up-going fluid along walls of the channel with the\r\none issued from a flat nozzle located in its entry section. The fluiddynamic\r\nand heat-transfer characteristics of vented vertical channels\r\nare investigated for constant heat-flux boundary conditions, a\r\nRayleigh number equal to 2.57 1010, for two jet Reynolds number\r\nRe=3 103 and 2104 and the aspect ratio in the 8-20 range. The system\r\nof governing equations is solved with a finite volumes method and an\r\nimplicit scheme. The obtained results show that the turbulence and\r\nthe jet-wall interaction activate the heat transfer, as does the drive of\r\nambient air by the jet. For low Reynolds number Re=3 103, the\r\nincrease of the aspect Ratio enhances the heat transfer of about 3%,\r\nhowever; for Re=2 104, the heat transfer enhancement is of about\r\n12%. The numerical velocity, pressure and temperature fields are\r\npost-processed to compute the quantities of engineering interest such\r\nas the induced mass flow rate, and average Nusselt number, in terms\r\nof Rayleigh, Reynolds numbers and dimensionless geometric\r\nparameters are presented.","references":null,"publisher":"World Academy of Science, Engineering and Technology","index":"Open Science Index 33, 2009"}