Billboard Wind Load Analysis | Fluid-Structure Interaction (FSI) Simulation

When a strong wind hits a large structure like a billboard, two critical phenomena occur: the airflow is diverted around the obstacle, and the structure itself bends or vibrates under the pressure. To accurately simulate this, we use Fluid-Structure Interaction (FSI).

In this comprehensive tutorial, we use ANSYS Fluent to calculate wind pressure and then couple those results with ANSYS Static Structural to determine how much the billboard deforms. This "One-Way FSI" approach is essential for engineering safe and durable outdoor structures.

---

Phase 1: Geometry & Fluid Domain

The first step is creating a realistic 3D model in DesignModeler.

• Billboard: A 6m x 3m board mounted on a 5m tall circular pole (0.5m diameter).
• Fluid Domain: An air box measuring 30m x 30m x 80m to allow for fully developed flow and wake formation.
• Boolean Operation: We subtract the billboard from the air box using the "Subtract" tool, ensuring we preserve the tool body (the billboard) for the subsequent structural analysis.

Phase 2: CFD Setup & Wind Load

With the mesh generated, we move to ANSYS Fluent to simulate the wind behavior.

• Models: We use the K-Epsilon (Standard) turbulence model to handle the high-velocity air.
• Boundary Conditions: A velocity inlet of 15 m/s is applied. We also set the outer boundaries to Symmetry to simulate an open atmosphere.
• Drag Force: Using report definitions, we monitor the total drag force (Z-direction) acting on the billboard walls until convergence.

Phase 3: Structural Analysis & Deformation

This is where the FSI coupling happens. We link the Fluent "Solution" cell directly to the "Setup" cell of Static Structural.

• Material: Structural Steel.
• Imported Load: We map the pressure distribution calculated in Fluent onto the structural surfaces of the billboard.
• Constraints: A Fixed Support is applied at the bottom of the pole, along with Standard Earth Gravity.

Results Outcome

After solving, we analyze several key outputs:

• Total Deformation: Shows the maximum bending at the top edges of the billboard.
• Equivalent Stress (Von-Mises): Reveals that the most stressed point is the joint between the board and the pole.
• Flow Visualization: 3D Streamlines and 2D Velocity contours show the formation of eddies (vortices) behind the structure.

Master FSI Simulations

Watch the full 29-minute walkthrough to see every setting and click required to complete this project.

▶ Subscribe to ANSYS Tutor