Architectural: External Flow around an Atrium

What You'll Build

This lesson walks you through a complete CFD simulation of external airflow around a building atrium — a structure rooted in ancient Roman architecture and reborn in modern multi-story buildings as a glass-roofed space used for lighting and natural ventilation. Atriums rely on two fundamental natural phenomena — the greenhouse effect and the chimney effect — and understanding the surrounding airflow is the first step in designing them effectively.

In this project, you'll investigate how an 8 m/s horizontal wind interacts with the walls of an atrium, generating regions of high pressure, separation, recirculation, and acceleration around the structure.

What You'll Learn

• How to design a 3-D external flow domain (3.35 m × 2.21 m × 3.9 m) around an architectural structure in Design Modeler

• How to generate a refined unstructured mesh (~1.95 million elements) with finer cells near the building walls for accurate boundary-layer resolution

• How to configure a pressure-based steady-state solver for external aerodynamic problems

• How to set up the RNG k-ε turbulence model with standard wall functions — well-suited for separated and recirculating flows around bluff bodies

• How to apply external-flow boundary conditions: velocity inlet (8 m/s), pressure outlet (0 Pa gauge), and stationary walls

• How to choose appropriate SIMPLE pressure–velocity coupling with second-order discretization for pressure and momentum

• How to initialize the domain with atmospheric pressure (101325 Pa) and a uniform freestream velocity

• How to post-process 2-D and 3-D pressure and velocity contours, pathlines, and velocity vectors on the XY plane, plus the pressure distribution on wall surfaces

Why It Matters

External flow analysis around buildings is the backbone of modern architectural engineering — driving decisions about façade design, pedestrian wind comfort, natural ventilation, and structural wind loading. This lesson gives you a reusable workflow you can apply to any external building flow problem.