Pressurized hydraulic flushing is a technique to remove deposited sediments in reservoirs. Dam outlets are opened to discharge sediments through the outflow. Reservoirs cannot be experimentally simulated at a real-life scale under various scenarios. Therefore, numerical simulations represent an efficient and effective alternative and help optimally manage deposited sediments in reservoirs. This paper numerically simulated flow and sediments in the Sefid-rud Dam, Iran, using the Flow-3D model. The numerical model was calibrated using real-life flushing data of the dam. Then, the effects of the water level at the beginning of pressurized flushing and the number of open outlets were explored by analyzing the changes in the longitudinal bed level, scour around the outlets, and sediment removal. It was found that the numerical model was effective and efficient in identifying the optimal initial reservoir level and outflow in a dam.