FREE CONVECTION FROM OPTIMUM SINUSOIDAL SURFACE EXPOSED TO VERTICAL VIBRATIONS

This paper presents a numerical study of the effect of forced vibrations on the heat transfer coefficient from sinusoidal surface by using ANSYS Fluent 15.0 program, besides a theoretical investigation to calculate the optimization of the amplitude to wavelength ratio of the sinusoidal surface. The physical model of the test surface can be presented as a copper plate having a sinusoidal upper surface, when it is heated by constant heat flux ranging as (250, 500, 750, 100, 1250 and 1500 w/m2) and vibrating with a range of frequencies (5, 10, 15, 20 and 25 Hz) including different vibration amplitude (3, 4 and 5 mm). This study is conducted for three different positions of test section: horizontal, vertical and downward heating inside air enclosure. The vibration parameters is defined to the ANSYS Fluent as user define function and this study is performed for three different positions of sinusoidal surface: horizontal, vertical and facing downward. This study concluded that the influence of vibration generally enhances the heat transfer coefficient and the vibrational mean Nesselt number (?Nuv?_mean), where they gain (9.5%) increasing in the horizontal position, (7.5%) increasing in the vertical position and (5.8%) increasing in the facing downward position due to vibrations existence. According to the current investigation, the vibrational mean Nesselt number depends on the Rayleigh number, applied frequency and the positions of the sinusoidal surface.