Natural convection in a tank of oil: experimental validation of a numerical code with prescribed boundary condition

This work presents a numerical and experimental analysis of the thermal stratification inside a tank containing thermal oil. Starting from an initial condition of uniform temperature, the tank is submitted to a cooling regime in the natural convection provoked by the thermal losses to the environment. The numerical analysis is accomplished with a two-dimensional model in cylindrical coordinates with the Finite Volumes method. The program is fed with polynomials originated from experimental tests, in function of the tank height and time, prescribing the tank sidewall temperature. The bottom and the top of the tank were thermally insulated. The temperatures of the tank sidewall and centerline were measured with copper-constantan thermocouples. Results of the temperature variation at the centerline, along the time and for several tank heights, are presented. A dynamic analysis of the problem is presented through velocity fields. The numerical results show a good agreement with the experimental results.