Defence Lab Jodhpur, Defence Research & Development Organisation,
Ratanada Palace, Cantt Area, Jodhpur, Rajasthan 342011, India
Department of Mechanical Engineering, IIT Jodhpur
Prodyut R. Chakraborty
Department of Mechanical Engineering, IIT Jodhpur, 342037, India
The gravity driven vertical falling film is being studied since last five decades with various facets of hydrodynamic behaviour as well as thermal behaviour. Different degree of polynomials [1-2] have been assumed for velocity profile for solving conservation equations of mass and momentum. Similarly, falling film along a heated plate  with variable physical properties  has also been investigated thoroughly. The existing methodologies are well established, but cumbersome. The advent of high speed computing devices along with hundreds of Gigabytes of RAM, makes Reynolds Transport Theorem (RTT) a very simple and convenient way of approaching the solution. Also, the heat transfer from the free surface of the falling film is rarely studied. In the present work RTT is applied to capture the hydrodynamic and thermal boundary layers simultaneously. The hydrodynamic boundary layer is attached to the solid vertical surface over which film flow occurs due to gravity. The thermal boundary condition on the solid wall is adiabatic, while heat transfer with the ambient occurs through the free surface. Hence, the thermal boundary layer is attached to the free surface, making the problem very interesting. The problem is relevant to film cooling or heating through exposure of the film to cold or hot ambient conditions.