The Study of Impact of Obstacle Shape on The Characteristics of Transverse Waves

Abstract

In many cases the collection of obstacles stand against water flow direction and by passing water through these obstacles, vortexes are created in downstream of them and by overlapping of these vortexes, surface waves perpendicular to the flow direction are formed. In this study the impact of obstacle shape on the characteristics of transverse waves are investigated.For this purpose, cylindrical obstacle and cubic obstacle are used. Discharges 5, 15 and 25 l/s and insertion of obstacles in parallel with ordering of 60*60,60*120,120*120 and 180*180 are considered. Totally 36 experiments were performed. The results showed that the shape of obstacles has high impact on the formation of transverse waves. The maximum amount of relative amplitude (A/H ) (A : The maximum wave amplitude , : depth of flow) was occurred for cylindrical obstacle with amount of 61.10% in arrangement of obstacles of and discharge equal to 5 l/s and the minimum value of was occurred for cubic obstacle for side current collision with amount of 6.00% in arrangement of obstacles of and discharge equal to 25 l/s. Equations for estimating of Strouhal Number were presented, using SPSS software developed. According to presented equations, Strouhal number has direct comparison with (P: Distance between obstacles, : Diameter of obstacles ) in cylindrical obstacles and has inverse comparison in two situations of cubic obstacles.

Keywords

• transverse waves
• strouhal number
• frequency of waves
• density of obstacles