Open Channel Flow: Short Wave in the Sea

What You'll Build

This lesson walks you through a CFD simulation of short waves on the sea surface — a fundamental problem in coastal, marine, and offshore engineering. Using ANSYS Fluent's ability to generate waves directly at a boundary, you'll create a realistic propagating wave field and track how the air–water interface evolves over time, all based on First-Order Airy (linear) wave theory.

This is your introduction to wave generation in CFD, a capability that underpins the design of breakwaters, offshore platforms, ships, and coastal structures.

What You'll Learn

• The basics of First-Order Airy wave theory and how it's applied inside Fluent

• How to design a 2-D sea domain (210 cm long × 76 cm high) in SpaceClaim

• How to generate an unstructured mesh (~55,000 cells) suited to free-surface wave tracking

• How to set up the VOF multiphase model with air and water phases, sharp interface modeling, and explicit formulation with implicit body force

• How to apply the open-channel wave boundary condition to send waves into the domain from the inlet

• Why a transient, pressure-based solver with the laminar viscous model is appropriate for this wave problem

• How to configure adaptive time stepping for stable, efficient wave propagation

• How to use PRESTO! pressure discretization and Compressive volume-fraction discretization to keep the interface sharp

• How to patch the initial water region and post-process velocity contours, observing how moving waves induce vortices and turbulence in the air above the surface

Why It Matters

Wave modeling is essential across naval architecture, coastal protection, renewable wave energy, and offshore oil and gas. The open-channel wave boundary condition you master here is the gateway to simulating realistic ocean environments — from ship seakeeping to wave-structure interaction.