NUMERICAL STUDY OF CLOSED CAVITY ASPECT RATIO ON NATURAL CONVECTION

Claudio Torres¹; Rogerio Gonçalves dos Santos¹

¹ Faculty of Mechanical Engineering - UNICAMP

doi:10.20906/CPS/CILAMCE2017-0191

Resumo

Natural convection in closed cavities has been studied in CFD in the last four decades. This spontaneous method of heat transfer has an especial interest in thermal sciences, fluid mechanics and a wide range of applications in engineering. In the present work, the aspect ratio in natural convection was numerically analyzed in a rectangular cavity heated on one of the sides and cooled on the opposite side. Temperatures of the different walls were assumed to be constant. The objective of these studies was to determine the effects of the aspect ratio H/L (Height/Length) and the numerical scheme on flow behavior and heat transfer in the cavity. The simulations were running using a code that was developed homemade on C++ language. Solving the dimensional equation of Navier-Stoke, Mass, and Energy balance on steady state, for non-compressible fluid in laminar flow. Implementing a SIMPLE algorithm, to couple the differential equations of velocity and pressure. Adopting the Boussinesq's hypothesis to couple the differential equation of energy balance, that suppose the same density in every point of a regular mail, but using a supposed ratio between the vertical forces and the gradient of temperature. Applicable only on non-compressible fluids. Numerical simulations were done for aspect ratios 0.25, 0.5, 1.0, 2.0 and 4.0 and Rayleigh number 103, 104, 105 and 106 using the UpWind, Exponential and Central schemes. Results show that the aspect ratio has lower influence in the temperature and streamlines fields than Rayleigh number.

Palavras-chave: NATURAL CONVECTION; CLOSED CAVITY; ASPECT RATIO