Which physical properties affect the film coefficient ? How film coefficient are correlated ?

Thermal conductivity, viscosity, density, and specific heat affect the film coefficient.
For a given velocity and fluid, the film coefficient depends upon the direction of flow of fluid relative to the heating surface. With free or natural convection, for a given arrangement of surface, the film coefficient also depends on the coefficient of thermal expansion, temperature difference between surface and fluid, and on the local gravitational acceleration. With forced convection at low rates of flow, particularly with viscous fluids such as oil, laminar motion may prevail and the film diameter depends on thermal conductivity, specific heat, mass rate of flow per tube, and length and diameter of the tube. The film coefficients are correlated in terms of dimensionless groups of the controlling factors.