چكيده به لاتين
Wood is an integral part of the river ecosystem, and the number of management projects using log placement is increasing. Logs are used in river engineering to reduce channel velocity, affect sedimentation, and bed sediment erosion, protect infrastructure, and are considered a more environmentally friendly alternative. Physical model experiments are conducted to investigate how the wood position and submergence level affect the turbulence structure and velocity. In this research, by placing wooden logs in the flow path, changes in velocity and turbulence kinetic energy and the effects of placing wooden logs at different angles in the center of the channel and the channel wall on the flow characteristics will be investigated. The research results show that the velocity decreases after the log is placed in all the flow's longitudinal profiles while the turbulence's kinetic energy increases. So that for logs with submergence degree less than 1.5, the flow must travel a distance of 10 times the length of the log from the beginning of the location of the log to reach the speed before the log was placed. But with the increase in the submergence degree, this distance is cut in half and is almost equal to 5 times the length. Experiments also show that the minimum speed for a submerged log is 1.5 times greater than emergent logs of the same length. It can be seen that the minimum velocity decreases with the change in the diameters of the logs as the submergence degree decreases. The following shows that the log submergence degree affects the position and size of the turbulence peak. So, the turbulence in the rise of the submerged log is weaker than that of the emergent log. And also, with the increase of submergence degree, the flow will experience less turbulence. the logs with small submergence degrees and those placed at an angle to the flow, a mixed case with two peaks in turbulence occurs. So that the first turbulence peak occurs approximately 1.5 times the diameter of the log, and the second turbulence peak occurs at a distance equal to 2.5 times the length of the log from the location of the logs. And for logs with a submergence degree higher than 1.5, the peak of the kinetic energy of turbulence occurs strictly downstream of the log.
