Fluid Film: Liquid Film Flow
This tutorial demonstrates how to use the fluid film modeling capability of Simcenter STAR-CCM+. It simulates the progress of a rectangular film of water flowing down the wall of a three-dimensional duct.
Water flows down the wall (wetted wall in the following figure) due to gravity, forming a liquid film in the process.

The initial water is 1 mm thick and covers a wall length and width of 250 mm and 200 mm, respectively, and is placed at the top wall. The surrounding gas is initially at rest. The simulation is run using the implicit unsteady solver for a simulated time of 10 seconds, which is long enough to satisfy the similarity condition. For the first 1000 time steps, the time step size is set to 0.001 seconds. Thereafter, a time step size of 0.01 seconds is used.