This report shows how we used Fluid-Structure Interaction (FSI) to study what happens when wind hits a vertical beam using both ANSYS Fluent and ANSYS Structural. FSI simulation is super important because it helps engineers see how fluid flows and solid structures affect each other at the same time. In many real-world cases like tall buildings, bridge pillars, wind turbines, and offshore structures, wind loading causes structural deformation that changes how the air flow behaves, which then changes the forces on the structure in a back-and-forth cycle. Our coupled analysis uses computational fluid dynamics (CFD) to calculate wind forces and structural mechanics to find the resulting beam deflection and displacement. This kind of two-way FSI is much better than old methods because it captures the full physics of how the beam bends under wind pressure and how this bending then affects the airflow patterns. Understanding these FSI phenomena helps engineers build safer, more efficient structures that can handle wind-induced vibration without failing. This study is essential. Same as always, this study relies on a reference paper entitled “ An evaluation of quasi-Newton methods for application to FSI problems involving free surface flow and solid body contact”.

• Reference [1]: Bogaers, Alfred EJ, et al. “An evaluation of quasi-Newton methods for application to FSI problems involving free surface flow and solid body contact.” Computers & Structures173 (2016): 71-83.

Figure 1- Schematic outline of the problem [1]

Simulation Process

The coupling of ANSYS Fluent and ANSYS Structural is required to see interactions between solid and fluid regions. Two regions are initially designed using Design Modeler. It is then discretized into a structured grid. The vertical beam is made of steel with Young`s Modulus of 2.7e+7 Pa and 0.35 Poisson`s Ratio. Wind blows with 0.1 m/s velocity, colliding with a vertical beam and exerting forces on it.

Post-processing

The pressure and force contours (Figures 2 and 3) tell us something really important about how wind pushes on the tower. On the left side, we see high pressure (around 16 kPa) and strong forces (about 0.12-0.14 N) that push directly against the tower. This is where the wind hits first. Then on the right side, the pressure drops to negative values (about -4 kPa), creating a suction effect that tries to pull the tower. This pressure difference between front and back is what creates the total wind load. The sharp line in the middle shows where we split the model for the analysis. What’s interesting is how evenly distributed the pressure is across each section – this means our tower design spreads the load well without creating dangerous concentration points where failure might start.

Figure 2: Pressure & Force contours showing wind load

The total deformation results in Figure 3 show exactly how much the tower bends under these wind forces, and it’s a classic cantilever beam behavior. The bottom of the tower barely moves because it’s fixed to the foundation, while the very top (red) bends the most – reaching a maximum of 9.06 mm. This bending follows a smooth gradient from bottom to top, showing that the tower flexes naturally without any weird kinks or weak spots. For a tower that’s about 2000 mm (2 meters) tall according to the scale, this deformation is less than 0.5% of its height, which is well within safe limits. The gradual color change from blue to red tells us the structure is sharing the load efficiently throughout its entire length. The steel is working exactly as it should – bending slightly to absorb the wind energy but staying strong enough to avoid permanent damage.

Figure 3: Total deformation analysis