In process engineering a falling film is a thin liquid film which flows down an inclined plate by the action of gravity. Falling films are employed in various fields, like the food industry, the pharmaceutical industry or in power plants. They have the advantage of a good heat transfer and a small hold up. Furthermore, they have a large surface for the exchange between gas and liquid (like in gas scrubbing).
A falling film flowing down a vertical wall is always hydrodynamically unstable. However, if the Reynolds number is very small, the waves may not be seen.
In the EU project EasyMED I simulated evaporating seawater falling films. Turbulence wires were employed to improve the heat transfer.