This paper presents a model for local scour at submerged weirs with downstream slopes that uses a coupled moving-mesh and masked-element approach.In the developed model,the fluid-sediment interface is tracked using a moving-mesh technique,and the effects of the structure on the hydrodynamics and bed morphology are resolved using a masked-element technique.Compared to traditional sediment scour models,based on the moving-mesh technique,the present model has the advantage of allowing for a simpler setup of the computational grids and a larger-amplitude deformation.Laboratory experiments on local scour at a submerged weir with a downstream slope were conducted,which provided bed profiles at different time instants.The results obtained by the present model are compared to the experimental data.The comparisons demonstrate the performance of the model in satisfactorily predicting local scour at a submerged weir with a downstream slope.The model was further modified and employed to carry out additional computations to investigate the influence of various parameters and sub-models. 相似文献
Canonical balanced dynamic equations involving vertically sheared horizontal flow with heat or mass sources have emerged recently in systematic multi-scale modeling of the equatorial wave guide on a wide range of spatio-temporal scales. Here, a new self-contained derivation of these equations is developed briefly in a context for potential applications to the hurricane embryo. These canonical balanced equations are studied through a combination of exact solutions and simple numerics. The results below include elementary exact solutions given by velocity fields that are linear in the spatial coordinates combined with an exact nonlinear stability analysis for vertical vorticity amplification in such a preconditioned environment. Other elementary solutions studied here include the evolution of radial eddies, which represent “hot towers” in the hurricane embryo in a suitable radial preconditioned background environment. 相似文献
The Sanandaj–Sirjan Zone (SSZ), as the metamorphic-magmatic core of the Zagros Orogen in southwestern Iran, contains several styles of gold deposit of Phanerozoic age. The northern SSZ includes an ENE-trending goldfield belt. This area that encompasses the main orogenic gold deposits, e.g., Qolqoleh, Kervian, Qabaqhlujeh, and the Barika VMS goldfield, was chosen for this research to study the spatial and temporal relationships between gold mineralization and orogenic phases. Regarding the rock unit variations, metamorphism, magmatism and the settings of the structures, the study area is divided into four distinct tectonic blocks, separated by three main NW-trending thrust faults (suture lines) including, from NE to SW, the Tamugheh, the Ebrahim Hesar and the Zagros main thrust (ZMT) faults. The area between the Tamugheh and Ebrahim Hesar faults is a tectonized/uplifted basement of accretionary wedge-originated thrust slivers, hosting the above orogenic gold mineralizations. The other area between the here termed Ebrahim Hesar fault and the ZMT is an island-arc basin, proposed here as the Sardasht–Barika zone, including the only recognized massive sulfide gold district all over the SSZ, named Barika. The Barika goldfield was metamorphosed, deformed and enriched due to the island-arc collision to the Arabian continent, before the closure of Neotethys on the eastern flank. 相似文献
In this paper, a multiphase three-dimensional numerical reproduction of a large-scale laboratory experiment of tsunami-like bore interaction with a surface-piercing circular column is presented. The numerical simulation is conducted using OpenFOAM. A dam-break mechanism is implemented in order to generate tsunami-like bores. The numerical model is validated using the results of experiments performed at the Canadian Hydraulics Center of the National Research Council in Ottawa, Canada. Unsteady Reynolds-Averaged Navier–Stokes equations are used in order to treat the turbulence effects. The Shear Stress Transport k–ω turbulence model showed a high level of accuracy in replicating the bore–structure interactions. A scaled-up domain is used to investigate the influence of bed condition in terms of various downstream depths and roughnesses. Finally, a broad investigation on bore propagation characteristics is performed. The stream-wise forces exerted on the structural column as well as the bore velocity are compared and analyzed for smooth, rough, dry and wet beds with varying depths.
In this paper effect of fine mineralogy on mechanical behavior of unsaturated silty sand in different fine contents and divers confining pressure has been studied. All samples were molded with constant equivalent granular void ratio well-known parameter already proposed for characterizing silty sand behavior in saturated state. This manner of study allow to investigate also the validity of equivalent granular void ratio concept in unsaturated state. For this purpose, a series of triaxial tests were performed on the sand specimens with different percentages of silt in the undrained saturated (CU) and unsaturated (CW) conditions. The results showed that the material types and aggregate distribution of the fines have enormous effects on the silty sand behavior. In addition, the shear strength in the unsaturated specimens changed as a function of the initial applied matric suction. A fewer performance of equivalent intergranular void ratio in the case of unsaturated state in comparison of saturated states was observed.