Shallow Water Flow Having a Lee Hydraulic Jump over a Mountain Range in a Channel of Variable Width

A Numerical Study of the Local Downslope Wind “Yamaji-kaze” in Japan

“…The behavior of the hydraulic jump is quite sensitive to the existence of the col, while the upstream blocking is rather insensitive to the existence of the col. The response of the hydraulic jump to the existence of a col has qualitative similarities to the behavior of the hydraulic jump in a shallow water flow over a mountain range in a channel of variable width, which has been presented by Saito (1992).…”

“…The behavior of the hydraulic jump is quite sensitive to the existence of the col, while the upstream blocking is rather insensitive to the existence of the col. The response of the hydraulic jump to the existence of a col has qualitative similarities to the behavior of the hydraulic jump in a shallow water flow over a mountain range in a channel of variable width, which has been presented by Saito (1992).Numerical experiments using the real orography of Shikoku Island and the thermal stratification observed on 21 April 1987 are performed as an example of the simulation of a typical Yamaji-kaze, and the development and movement of the internal hydraulic jump is simulated under a time-changing wind profile. It is shown that the timing of the onset of the Yamaji-kaze, which is too early in the two-dimensional simulation, is ameliorated in the three-dimensional simulation.…”

“…Recently Saito (1992) expanded Houghton and Kasahara's (1968) theoretical model and examined the behavior of the hydraulic jump in the shallow water flow over a mountain range in a channel of variable width. According to his results, in the unsteady state in which the jump moves leeward the moving speed of the shallow water jump increases with the decrease of the channel width, and in the quasi-steady state in which the jump stays the shallow jump occurs more on the leeward side with the decrease of the channel width.…”

“…The behavior of the mountain flow over a mountain range with a col has been seldom investigated, either theoretically or numerically. Most recently, Saito (1992) studied the behavior of a hydraulic jump in shallow water flow over a mountain range in a channel of variable width by expanding Houghton and Kasahara's (1968) theoretical model. According to his results, in the unsteady state in which the jump moves leeward, the moving speed of the jump increases with the decrease of the channel width, and in the quasi-steady state, in which the jump stays over the lee slope of the mountain range, the jump occurs more on the leeward side with the decrease of the channel width.…”

Formation Mechanism of a Low-Level Jet during the Passage of Typhoon Ma-on (2004) over the Southern Kanto District

“…They showed that much of the low-level acceleration and subsidence at the gap exit was forced by downslope flow off the surrounding terrain. As other studies (Arakawa 1969(Arakawa , 2006Saito 1992) indicated, the strong wind events on the gap or col of the complex mountain terrain often attribute to the combination mechanism of the gap flow and the downslope winds.…”