抄録
Local scours around river structures during flood are affected not only by local 3D flow around structures but also by the larger scale phenomena of flood flow and bed variations. To compute local scouring around structure with computing large scale phenomena, we have developed the bottom velocity computation method, in which depth-averaged horizontal vorticity and water surface velocity equations are computed with shallow water equations to evaluate vertical velocity distribution. However, the assumption of shallow water conditions confines the applicability to relatively large scale phenomena. This paper presents applicable range and limit of 2D, 3D and quasi-3D numerical model by shallowness, which is defined as the ratio of representative water depth to representative horizontal scale. Then, we develop the general bottom velocity computation method without the shallow water assumption and apply to flow field around a cylinder on flat rough bed.
