This paper aims to numerically investigate fluid–structure interaction (FSI) problems through the coupling simulation of OpenFOAM and CalculiX, with a focus on the validation of the Turek and Hron benchmark. The study analyzes the impact of different beam lengths on flow patterns and vibration simulations. FSI simulation is crucial for understanding and predicting the dynamic response of immersed elastic bodies in viscous fluid media in engineering and industry. The finite volume method and finite element method are employed to construct 2D models, simulating the vortex-induced vibration of a beam attached to a cylinder, and predicting the optimal geometry for the beam and velocity regions. The developed FSI models are validated against the Turek and Hron benchmark, showing good agreement with benchmark data. The study further explores the vorticity in the fluid and stress in the structural field under various beam lengths and flow velocities, as well as their impact on flow pattern and vibration simulations. Results indicate that adjusting the beam length can effectively suppress the vortex behind the cylinder, reducing vibration in the FSI system. This research not only provides an efficient numerical simulation method for FSI problems but also offers theoretical guidance and solutions for practical engineering problems.