RT - Journal Article T1 - Numerical Investigation of Guide Walls Geometry at the Entrance of Dam Spillway (Case Study: Karun-3 Dam) JF - JSTNAR YR - 2022 JO - JSTNAR VO - 26 IS - 3 UR - http://jstnar.iut.ac.ir/article-1-4189-en.html SP - 211 EP - 229 K1 - Ogee spillway K1 - USBR standard profile K1 - Sharp crested weir K1 - Guide wall K1 - Numerical simulation AB - One of the most important hydraulic structures in a dam is the spillway. The design of the ogee spillway crest is based on the lower profile of the free-flow jet passing through the sharp-crested weir. When the downstream ogee spillway profile for the design discharge conforms to the lower profile of the free-jet passing through the sharp-crested weir, the pressure on that surface of the spillway becomes zero. In this study, the design of the ogee spillway was performed initially based on both two- and three-dimensional numerical modeling and then compared to the USBR standard method. The comparison of the final numerical and analytical results showed that although the vertical two-dimensional outputs were completely in agreement with the USBR standard profile, the three-dimensional profiles were different because in this model, guide walls were not considered. According to the analysis, if the flow entering the spillway is parallel to its axis, the lower profile of the sharp-edge spillway will be in complete agreement with the standard profile. Since, the design of guide wall geometry for ogee spillways is carried out using physical modeling which iteratively revises during a high-cost trial and error procedure, this research based on the case study of the spillway of Karun-3 dam has been tried using numerical modeling. The closest geometry to the geometry of the overflow guide wall was obtained which creates the least difference in transverse velocities. In this way, the design of guide walls can be done with more accuracy and low cost in comparison to physical modeling. LA eng UL http://jstnar.iut.ac.ir/article-1-4189-en.html M3 10.47176/jwss.26.3.35641 ER -