Studies on the Reclaimed Land Dike from the Standpoint of Agricultural Engineering I. The Model Experiments on the Wind-Flow crossing over the Reclaimed Land Dike by using Water-Flow through a Long Channel

This article deals with the phenomena of wind flow crossing over the re- claimed land dike using water-flow through a long channel in which the model dike (scale 1/50) is laid. For the purpose of taking a photograph of the phenomena, silver dust was floated down at the flow-water surface, and the states of flow, eddies etc. were photographed ( see phot. (1)~(10)). Also the author investigated the laws of similality in the present cases. The present experiments led to the following conclusions. (i) The law of similality (2) was satisfied in these cases. (ii) The size, the numbers of eddies and the states of flow were changed by the shapes of the dikes as follows : A. If a parapet is held, the angle of the stream line at the top of the dike and the scale of eddies is larger against no parapet, and restoration requires a relatively longer distance. B. As the stream-line is smooth in what is called a streamline-shaped dike (steep in front and gentle in back), a short distance is required for restoration. But the streamline in what is called the streamline-shaped dike yields relatively more, smaller rotational eddies, so they restore faster. C. The wider crown makes relatively slower and larger eddies, so a longer distance is required in that case.