Marine: Sea Robot Motion Immersed in Water

What You'll Build

This lesson walks you through a CFD simulation of a sea robot moving through water using the Dynamic Mesh technique — the essential method for problems where a body physically moves through the fluid domain and the computational cells must change shape and position over time.

In this project, the robot (modeled as a cube) starts on one side of the domain and travels toward the inlet against an oncoming water stream, letting you study the pressure buildup ahead of it and the wake region trailing behind.

What You'll Learn

• When and why a Dynamic Mesh is mandatory — whenever the location or shape of computational cells changes during the simulation

• How smoothing and remeshing work together to maintain high-quality elements as the body moves, preventing the mesh degradation that causes solver errors

• How to configure remeshing intervals (here, every 50 iterations) to regenerate a fresh, high-quality mesh

• How to design a 2-D moving-body domain in Design Modeler and mesh it (~30,010 elements) in ANSYS Meshing

• Why a transient solver is required for any Dynamic Mesh problem

• How to impose a prescribed velocity profile on the moving body (3 m/s in the X-direction over 0–3 seconds)

• How to set up the surrounding flow with an inlet water velocity of 1.5 m/s using the standard k-ε turbulence model

• How to post-process velocity, pressure, turbulent viscosity contours, and streamlines — observing the elevated stagnation pressure ahead of the robot and the wake region behind it

Why It Matters

Dynamic Mesh is the gateway to simulating real motion — submarines, AUVs, valves, pistons, projectiles, and store separation. Mastering smoothing and remeshing here equips you for an entire class of moving-body CFD problems.