Abstract
In this study, regarding a topographic change around a cylinder in a wave-current coexistence field, the authors investigated the reproduction of the phenomenon and its fast computation by a three-dimensional numerical analysis for a large-scale movable-bed experiment under forward current condition. In the analysis, we introduced a time interval Δtz for the topographic change that is larger than the time interval Δt for the flow, and accelerated the analysis by using the same number of calculations for the flow and the topographic change while allowing the analysis to progress through time in Δtz. As a result, under the experimental condition, no difference in scour was observed when Δtz/Δt was varied from 10 to 100, and the analysis was 100 times faster than the analysis using only Δt. In addition, comparison with experiment on the final scour situation showed that the numerical model reproduced the maximum scour position from the front to the sides of the cylinder and the shape of the scour. However, the maximum scour depth in the analysis was two-thirds that of the experiment approximatory, and the model could not reproduce the scour and sedimentation shape at the back of the cylinder.
