عنوان مقاله [English]
When the fluid flow passes through a cluster of rigid vertical cylinders, the overlap of shear layers and vortex resulted from the separation of the streamlines around each rod leads in the surface waves. These waves are categorized in three groups of standing oscillatory, transverse waves, and linear waves. The present study focused on this phenomenon based on laboratory tests in a rectangular flume. Wooden rods 0.35 meter in height and 0.025 meter in diameter are placed in the flow path screwed on the bottom of the laboratory flume. By changing the hydraulic conditions of the flow, four types of surface waves are observed across the laboratory flume. In the condition of wave resonance, there is a direct relationship between the wavelength and the width of laboratory flume. The current study compares the frequency of the waves for the in-line and staggered arrangements of rods. Moreover by using dimensional analysis and SPSS software, two equations are proposed for determination of frequency of free surface transverse wave generated by vortex shedding in open channels.