排序方式: 共有43条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
An open channel flow with a flow depth close to the critical depth is characterised by a curvilinear streamline flow field
that results in steady free surface undulations. Near critical flows of practical relevance encompass the undular hydraulic
jump when the flow changes from supercritical (F > 1) to subcritical (F < 1), and the undular weir flow over broad-crested
weirs where the flow changes from subcritical (F < 1) to supercritical (F > 1). So far these flows were mainly studied based
on ideal fluid flow computations, for which the flow is assumed irrotational and, thus, shear forces are absent. While the
approach is accurate for critical flow conditions (F = 1) in weir and flumes, near-critical flows involve long distances reaches,
and the effect of friction on the flow properties cannot be neglected. In the present study the characteristics of near-critical
free-surface flows are reanalysed based on a model accounting for both the streamline curvature and friction effects. Based
on the improved model, some better agreement with experimental results is found, thereby highlighting the main frictional
features of the flow profiles. 相似文献
5.
Environmental Fluid Mechanics - Hydraulic jumps are commonly employed as energy dissipators to guarantee long-term operation of hydraulic structures. A comprehensive and in-depth understanding of... 相似文献
6.
Environmental Fluid Mechanics - In plunging jets and at hydraulic jumps, large amounts of air bubbles are entrained at the impingement of the liquid jet into the receiving body. Air is entrapped... 相似文献
7.
Dam-break flood waves are associated with major environmental disasters provoked by the sudden release of water stored in reservoirs. Ritter found in 1892 an analytical solution to the wave structure of an ideal fluid released during an instantaneous dam failure, propagating over initially dry horizontal terrain. This solution, though ideal, hence frictionless, is widely used to test numerical solutions of the Shallow Water Equations (SWE), and as educational tool in courses of fluid mechanics, given that it is a peculiar case of the Riemann problem. However, the real wave structure observed experimentally differs in a major portion of the wave profile, including the positive and negative fronts. Given the importance of an accurate prediction of the dam break wave, the positive and negative wave portions originating from the breaking of a dam with initially dry land on the tailwater reach are revisited in this work. First, the propagation features of the dry-front are investigated using an analytical boundary-layer type model (Whitham/Dressler/Chanson model) constructed matching an (outer) inviscid dynamic wave to an (inner) viscous diffusive wave. The analytical solution is evaluated using an accurate numerical solution of the SWE produced using the MUSCL-Hancock finite-volume method, which is tested independently obtaining the solution based on the discontinuous Galerkin finite-element method. The propagation features of the negative wave are poorly reproduced by the SWE during the initial stages of dam break flows, and, thus, are then investigated using the Serre–Green–Naghdi equations for weakly-dispersive fully non-linear water waves, which are solved using a finite volume-finite difference scheme. 相似文献
8.
Castro-Orgaz Oscar Cantero-Chinchilla Francisco N. Chanson Hubert 《Environmental Fluid Mechanics》2022,22(4):971-1003
Environmental Fluid Mechanics - The simulation of shallow flows over obstacles is an important problem in environmental fluid dynamics, including exchange flows over seabed sills, atmospheric flows... 相似文献
9.
10.
A tidal bore is a natural and fragile phenomenon, which is of great importance for the ecology of an estuary. The bore development
is closely linked with the tidal range and the river mouth shape, and its existence is sensitive to any small change in boundary
conditions. Despite their ecological and cultural value, little is known on the flow field, turbulent mixing and sediment
motion beneath tidal bores. Indeed, some striking features can be highlighted in two-dimensional simulations, such as large
velocity fluctuations and flow recirculation structures. Using Large Eddy Simulation method, the numerical results emphasised
the complicated turbulent structures and their unsteadiness under a tidal bore. 相似文献