Analysis of the rigid-body fluid–structure interaction on a log boom

Log booms are modular and floating structures that partially cross the hydroelectric power plant reservoir to retain and deflect floating objects in the river that can damage and clog the turbine and reduce energy availability. In rivers with a high volume of logs or vegetation, the correct design of these structures is essential to ensure the operability of the hydroelectric power plant. In order to aid in the design of log booms, this paper proposes a method to predict the hydrodynamics forces and movement of log boom lines using CFD tools. Due to the high computational cost of simulating the entire line, simulations are conducted only on a single log boom module using boundary conditions that simulate the interference effects from its adjacent ones, considering different velocity magnitudes and direction combinations. The individual module results are composed to obtain the expected forces on the log boom line. A towing tank experiment with a model-scale model of a segment of the log boom line is conducted to verify the reliability of the numerical model results, comparing the module movement (heave and pitch) and line extremity tension forces. The agreement between numerical and experimental approaches shows that the proposed method can be used to predict the tension in the log boom line and evaluate other conditions, log boom geometries, or line shapes.