Open channel flow refers to the movement of liquid with a free surface exposed to the atmosphere, typically driven by gravity. It commonly occurs in hydraulic structures such as spillways, canals, stilling basins, and river channels. One important parameter used to classify these flows is the Froude number, which compares inertial forces with gravitational forces and identifies whether the flow is subcritical, critical, or supercritical.
Designing such systems is challenging because open channel flows often involve strong surface deformation, turbulence, hydraulic jumps, and air–water interactions. Traditional hydraulic design methods and empirical guidelines are useful for initial sizing, but they provide limited insight into complex flow behavior and transient effects.
To address this, the blog by Ozen Engineering demonstrates the use of Computational Fluid Dynamics (CFD) through Ansys FreeFlow, which employs the Smoothed Particle Hydrodynamics (SPH) method to simulate free-surface flows. A simulation of a USBR Type III stilling basin is used as an example, where baffle blocks promote turbulence and dissipate energy. The model captures the formation of a hydraulic jump, allowing engineers to analyze velocity fields, free-surface motion, and energy dissipation before implementing real-world hydraulic designs.
Image courtesy: Ozen Engineering, Inc.