University of Tehran, College of AburaihanWater and Irrigation Management2251-629812220220622Scale Effects in Hydraulic Modeling with a Two-Dimensional Numerical ModelScale Effects in Hydraulic Modeling with a Two-Dimensional Numerical Model3753878793210.22059/jwim.2022.341971.983FASrwaHeidariGraduated Master Student, Department of Water Engineering and Management, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.BahmanFakouriPh.D. Candidate, Department of Water Engineering and Management, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.MehdiMazaheriAssociate Professor, Department of Water Engineering and Management, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.0000-0001-8670-1710JamalMohammad Vali SamaniProfessor, Department of Water Engineering and Management, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.0000-0002-2547-0821Journal Article20220421Hydraulic models are often used as a tool for the prediction of the hydrodynamic behavior of flow. But scale effects in the hydraulic modeling process due to deviations of the results from the prototype. This paper discusses to scale effect in the hydraulic flow model. The goal of the research is to investigate the effect of geometric distortion on the flow characteristics and the degree of deviation of the results of distorted models from the prototype, which is done using the two-dimensional numerical model MIKE21. First, the hydrodynamic conditions of the flow were simulated in four models of straight channel, convergent channel, divergent channel and curved channel with four degrees of distortion one (undistorted), two, five and 10. Then, assuming the similarity of the Froude number, the results of the models were compared with the prototype and the relative error in the result of channels was investigated. The results showed that the difference in depth and average velocity in distorted models with prototype is small, but the difference in transverse velocity profile of sloping model with prototype increases with increasing degree of distortion. So that the relative error in transverse velocity modeling in straight, convergent, divergent and curved channels with a degree of G10 was two, 29, 33 and 39 percent, respectively.Hydraulic models are often used as a tool for the prediction of the hydrodynamic behavior of flow. But scale effects in the hydraulic modeling process due to deviations of the results from the prototype. This paper discusses to scale effect in the hydraulic flow model. The goal of the research is to investigate the effect of geometric distortion on the flow characteristics and the degree of deviation of the results of distorted models from the prototype, which is done using the two-dimensional numerical model MIKE21. First, the hydrodynamic conditions of the flow were simulated in four models of straight channel, convergent channel, divergent channel and curved channel with four degrees of distortion one (undistorted), two, five and 10. Then, assuming the similarity of the Froude number, the results of the models were compared with the prototype and the relative error in the result of channels was investigated. The results showed that the difference in depth and average velocity in distorted models with prototype is small, but the difference in transverse velocity profile of sloping model with prototype increases with increasing degree of distortion. So that the relative error in transverse velocity modeling in straight, convergent, divergent and curved channels with a degree of G10 was two, 29, 33 and 39 percent, respectively.https://jwim.ut.ac.ir/article_87932_8b35a5fca74c883b4456280314474bd5.pdf