Abstract:Abstract. The southern coastal area of Korea has often been damaged by storm surges and waves due to the repeated approach of strong typhoons every year. The integrated model system is applied to simulate typhoon-induced winds, storm surges, and surface waves in this region during Typhoon Sanba in 2012. The TC96 planetary boundary layer wind model is used for atmospheric forcing and is modified to incorporate the effect of the land's roughness on the typhoon wind. Numerical experiments are carried out to inves… Show more
The characterisation of the aerodynamic roughness length (z 0) and the displacement height (d) is critical when modelling the wind field using the log vertical profile. It is known that the values of these parameters depend on land coverage and weather conditions. Thus, many authors have studied their relationship, providing typical values for each land cover. In this paper, we have performed a comprehensive literature review to collect the intervals of z 0 and d values for each land coverage. Using these intervals, we estimate their values using an optimisation technique that improves the results of a downscaling wind model. The downscaling model is a 3D adaptive, mass-consistent finite element model (Wind3D) that takes values from the HARMONIE-AROME or ECMWF mesoscale numerical weather prediction models. The optimisation is carried out by a memetic algorithm that combines the Differential Evolution method, a rebirth operator and the L-BFGS-B algorithm. The fitness function to be minimised is the root mean square error (RMSE) against observed wind data. This fast procedure allows updating the aerodynamic parameters for any weather condition. Numerical experiments have been carried out to show the performance of the methodology.
The characterisation of the aerodynamic roughness length (z 0) and the displacement height (d) is critical when modelling the wind field using the log vertical profile. It is known that the values of these parameters depend on land coverage and weather conditions. Thus, many authors have studied their relationship, providing typical values for each land cover. In this paper, we have performed a comprehensive literature review to collect the intervals of z 0 and d values for each land coverage. Using these intervals, we estimate their values using an optimisation technique that improves the results of a downscaling wind model. The downscaling model is a 3D adaptive, mass-consistent finite element model (Wind3D) that takes values from the HARMONIE-AROME or ECMWF mesoscale numerical weather prediction models. The optimisation is carried out by a memetic algorithm that combines the Differential Evolution method, a rebirth operator and the L-BFGS-B algorithm. The fitness function to be minimised is the root mean square error (RMSE) against observed wind data. This fast procedure allows updating the aerodynamic parameters for any weather condition. Numerical experiments have been carried out to show the performance of the methodology.
Section: Roughness Length and Displacement Height: Literature Reviewmentioning
confidence: 99%
“…Also in Table 2.1, there are some values of z 0 and d arising from applications of specific numerical models with their land cover databases. For example, [75] used them in lakes and lagoons; [101] in rocky outcrops and rocks, evergreen forests, salt marshes, wetlands, bare soils, and artificial coverages; [21] in evergreen forests; [57] used in no citrus fruit trees; [82] in grasslands; and [81] in ravine and road, parking or unvegetated pedestrian areas.…”
Section: Roughness Length and Displacement Height: Literature Reviewmentioning
This chapter is devoted to the introduction of some geographical and meteorological information involved in the numerical modeling of wind fields and solar radiation. Firstly, a brief description of the topographical data given by a Digital Elevation Model and Land Cover databases are provided. In particular, the Information System of Land Cover of Spain (SIOSE) is considered. The study is focused in the roughness length and the displacement height parameters that appear in the logarithmic wind profile, as well as in the albedo related to solar radiation computation. An extended literature review and characterization of both parameters are reported. Next, the concept of atmospheric stability is introduced from the Monin-Obukhov similarity theory to the recent revision of Zilitinkevich of the Neutral and Stable Boundary Layers (SBL). The latter considers the effect of the free-flow static stability and baroclinicity on the turbulent transport of momentum and of the Convective Boundary Layers (CBL), more precisely, the scalars in the boundary layer, as well as the model of turbulent entrainment. 2.1 Geographical data The main geographical information for wind and solar radiation modeling may be classified into two general databases, the topographical data related to the orography of the region to be studied and the land cover databases containing the information of the land uses. In this section, both are introduced.
“…Another key factor that makes it difficult to analyze and predict tailing run-out routing by numerical modeling is the difficulty of building the boundary of large-scale complex downstream terrains. Recently, some initial work, such as laboratory experiments and relatively simple deposition simulations of tailing fluid, has been attempted (Mizani et al, 2013;Zhang et al, 2015;Babaoglu and Simms, 2017;Gao and Fourie, 2019;Luo et al, 2017). These studies discussed the flow and rheological properties of tailing fluids in detail but did not take into account the influence of real terrain on the movement distance of tailing fluids.…”
Abstract. A tailing dam accident can cause serious ecological
disaster and property loss. Simulation of a tailing dam accident in advance
is useful for understanding the tailing flow characteristics and assessing
the possible extension of the impact area. In this paper, a
three-dimensional (3-D) computational fluid dynamics (CFD) approach was
proposed for reasonably and quickly predicting the flow routing and impact
area of mud flow from a dam failure across 3-D terrain. The Navier–Stokes
equations and the Bingham–Papanastasiou rheology model were employed as the
governing equations and the constitutive model, respectively, and solved
numerically in the finite volume method (FVM) scheme. The volume-of-fluid
(VOF) method was used to track the interface between the tailings and air.
The accuracy of the CFD model and the chosen numerical algorithm were
validated using an analytical solution of the channel flow problem and a
laboratory experiment on the dam-break problem reported in the literature.
In each issue, the obtained results were very close to the analytical
solutions or experimental values. The proposed approach was then applied to
simulate two scenarios of tailing dam failures, one of which was the
Feijão tailing dam that failed on 25 January 2019, and the simulated
routing coincided well with the in situ investigation. Therefore, the
proposed approach does well in simulating the flow phenomenon of tailings
after a dam break, and the numerical results can be used for early warning
of disasters and emergency response.
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