Rotating Disk Effect on Surrounding Airflow: Moving Wall

Rotating Disk Effect on Surrounding Airflow (Moving Wall) — ANSYS Fluent CFD Simulation

Description

This project demonstrates how a rotating disk influences the surrounding airflow using ANSYS Fluent's moving-wall boundary condition. A disk spinning in still air drags the nearby fluid into motion, setting up a distinctive velocity and pressure pattern around it — the same fundamental behavior that underlies propellers, turbomachinery, and other rotating equipment in aerospace applications. In this project, you'll model a 0.1-meter diameter disk (0.02 m thick) rotating at 5 rad/s within a confined 0.5 m × 0.5 m × 1 m room, gaining practical experience with rotational aerodynamics. As the opening project of the Mechanical Engineering: Beginner CFD Training Package, it introduces the moving-wall technique through the simplest single-phase rotating case.

Methodology

The three-dimensional computational domain is created in ANSYS Design Modeler, with a room measuring 0.5 m × 0.5 m × 1 m and the disk (0.1 m diameter, 0.02 m thick) positioned centrally for optimal flow analysis. The mesh is generated in ANSYS Meshing with approximately 716,870 cells, providing adequate resolution to capture the flow detail near the rotating surface. The disk's rotational motion is defined through a moving-wall boundary condition set to 5 rad/s, while the room walls are stationary no-slip surfaces. The laminar flow model is used to solve the governing equations, giving a clear view of the flow physics without the added complexity of turbulence.

Analysis

Through velocity and pressure contour analysis, you'll observe how the flow responds to the rotating disk: the maximum velocities occur at the disk's outer edge, the velocity decreases with distance from the rotating boundary, and the room air accelerates near the disk region. The pressure field shows a reduction near the disk surface and a symmetric pattern around it, with flow separating from the disk surface due to the rotational effects. Velocity vectors reveal the separation behavior, and the three-dimensional contours show symmetric results on both disk faces. By the end of this project, you'll be able to set up a moving-wall boundary condition to model a rotating component, choose an appropriate viscous model, and interpret the velocity and pressure fields around a rotating surface — building essential skills for aerospace CFD applications involving rotating components and preparing you for more complex propeller and rotor simulations.