NON-FOURIER HEAT-CONDUCTION IN A THIN-FILM SUBJECTED TO A SUDDEN TEMPERATURE-CHANGE ON 2 SIDES

Wave nature of heat propagation in a very thin film subjected to a sud den temperature change on both sides is investigated by solving the hy perbolic heat conduction equation, Analytical expressions are obtained for the temperature and heat flux distributions. Numerical computatio ns are performed in order to determine the behaviour of temperature an d heat flux distributions before and after the collision of the wave f ronts from two sides of the film. It is disclosed that in transient he at conduction a heat pulse is transported as a wave, which is attenuat ed in the film, and that non-Fourier heat conduction is extremely sign ificant within a certain range of film thickness and time. The Fourier 's law used in macroscale heat conduction cannot be applied. The resul ts also show that temperature overshoot occurs in the film having smal ler values of x(0)/tau(C) within a very short period of time, and that a fraction of heat is lost to the surroundings from the film through the side wall each time thermal waves rebound from the side of the fil m.