University of Tabriz Water and Soil Science 2008-5133 28 2 2018 06 22 Study of Obstacle Oscillation in the Presence of a Fix Upstream Obstacle, Using a Physical Model Study of Obstacle Oscillation in the Presence of a Fix Upstream Obstacle, Using a Physical Model 97 106 7836 FA MR Etminan M.Sc. Student of Water Structures., Dept. of Water Engin., Ramin Agriculture and Natural Resources University of Khuzestan, Iran A Hafari Assist. Prof., Dept. of Water Engin., Ramin Agriculture and Natural Resources University of Khuzestan, Iran S Jalili Assist. Prof., Dept. of Water Engin., Ramin Agriculture and Natural Resources University of Khuzestan, Iran J Zahiri Assist. Prof., Dept. of Water Engin., Ramin Agriculture and Natural Resources University of Khuzestan, Iran Journal Article 2018 09 25 Hydraulic structures in some cases, cause to produce obstacles in path of the flow that create oscillating vortices in downstream of the obstacles. Vortices produce oscillating forces to the obstacle that are harmful for the stability of structure. In recent years this phenomenon is used to create clean energy. In this study, oscillation of an obstacle in the presence of a fixed obstacle at the upstream was examined. The experiments on triangular block were carried out under varying discharge and different upstream distances. The main objective of this study was to investigate the effect of parameters of velocity and upstream obstacle distance on the oscillation frequency. Using dimensional analysis, the dimensionless parameters of Strouhal number, Reynolds number and ratio of distance to diameter were obtained. The charts of the relationship of the Reynolds number and also the ratio of distance to diameter vs. the Strouhal numbers were plotted. Finally, a new relationship was presented using data analysis and spss20 software to estimate the Strouhal number. Verifying the proposed relation, confirmed a fairly good prediction of this relation. Hydraulic structures in some cases, cause to produce obstacles in path of the flow that create oscillating vortices in downstream of the obstacles. Vortices produce oscillating forces to the obstacle that are harmful for the stability of structure. In recent years this phenomenon is used to create clean energy. In this study, oscillation of an obstacle in the presence of a fixed obstacle at the upstream was examined. The experiments on triangular block were carried out under varying discharge and different upstream distances. The main objective of this study was to investigate the effect of parameters of velocity and upstream obstacle distance on the oscillation frequency. Using dimensional analysis, the dimensionless parameters of Strouhal number, Reynolds number and ratio of distance to diameter were obtained. The charts of the relationship of the Reynolds number and also the ratio of distance to diameter vs. the Strouhal numbers were plotted. Finally, a new relationship was presented using data analysis and spss20 software to estimate the Strouhal number. Verifying the proposed relation, confirmed a fairly good prediction of this relation. https://water-soil.tabrizu.ac.ir/article_7836_3c3c175874618c929bda701c7dad0aae.pdf