Debris fows moving at high speed along valleys can bring disastrous consequences to downstream regions. Structural countermeasures are commonly installed along anticipated fow paths of debris fow risk areas in order to reduce debris fow mobility. The installation of cylindrical baffes, which are an open-type countermeasure, has increased because of their low construction cost, ability to flter rocks, and increased hydraulic continuity. Also, cylindrical baffes have advantages over rectangular baffes in that they have low drag force and effective energy dissipation caused by a higher interference of fows between baffes. However, comprehensive design guidelines for the specifcations and arrangement of cylindrical baffes are lacking. Baffe design and installation to date have been mainly based on empirical approaches by engineers, as the infuence of baffe array on debris mobility is not well understood. For the purpose of investigating the array effect of cylindrical baffes on fow energy dissipation, a series of small-scale fow tests was performed with installed baffes having varying heights and number of rows. High-speed cameras and a digital camera were installed at the top and the side of an experimental fume to capture fow behavior as simulated fows interacted with the baffes. Laser level sensors were also installed at the top of the fume to measure fow depth. After each test, the energy dissipation characteristics according to the height and number of rows of the baffes were analyzed. The analysis results showed that the use of baffes signifcantly decreased the downstream fow velocity and fow depth by 37% and 46% on average, respectively. Moreover, increasing the baffe height and the baffe number further enhanced the effect of baffes on the fow dynamics.