Vortex-induced vibration characteristics of three cylinders with isosceles-triangle arrangements at low Reynolds number

The geometric factors of multi-cylinders are one of the factors affecting the efficient energy capture of vortex-induced vibration aquatic clean energy. Based on the computational fluid dynamics numerical simulation method and overset mesh technology, an efficient dynamic model of VIV (vortex-induced vibration) of two-dimensional elastic-supported cylinders was established. The influence of different vertex angles on the VIV characteristics in the isosceles-triangle arrangement was investigated. The results show that the upstream cylinder is less affected by the vertex-angle, and the peak value moves to the left in the alpha-A(y)* curve of the downstream cylinders. As alpha increases, the upstream cylinder moves in an 8 shape and moves in the negative direction of the flow direction, while the downstream cylinders move in an O shape and gradually become narrow. The vortex shedding mode of downstream cylinders is mostly the P+S mode, and its amplitude is related to the position of the upstream cylinder's wake vortex effect. The lift and drag coefficients of the downstream cylinders are affected by alpha, while the dominant frequency of vibration is independent of the change in alpha and is greatly affected by Re. With the increase in Re, the positive correlation between the lift coefficient and transverse displacement gradually weakens.