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Arid Zone Flooding
Published in Saeid Eslamian, Faezeh Eslamian, Flood Handbook, 2022
Hassan Rezaei-Sadr, Saeid Eslamian
Overland flow: Runoff may be produced by both infiltration-excess and saturation-excess mechanisms. Runoff is routed in surface elements towards channels applying a four-point finite-difference solution to the kinematic wave equations via a cascade of hillslopes and channels. The routing process is described by the one-dimensional kinematic wave model (Woolhiser et al., 1990). Discharge at any distance and at any point in time along the runoff path is calculated numerically. Surface runoff depth and wave movement are governed by surface gradient, channel characteristics, roughness coefficient, and topography.
Factors Affecting Sediment Accumulation in Sedimentation Ponds
Published in Carl C. Trettin, Martin F. Jurgensen, David F. Grigal, Margaret R. Gale, John K. Jeglum, Northern Forested Wetlands, 2018
The surface runoff resulting from heavy rainfall and melting snow often causes erosion (meteorological factor in Figure 1). On the other hand, the degree of erosion depends on the type of ground surface, gradient of the terrain, length of the slopes, water permeability of the soil, etc. Precipitation, soil properties, and the gradient of the terrain are examples of local factors that cannot be regulated (Tiainen and Puustinen, 1989).
A micropolar continuum model of diffusion creep
Published in Philosophical Magazine, 2021
Diffusion along grain boundaries can be described by Fick's law in the form where is the flux of vacancies, is the diffusivity of vacancies along the grain boundary, and c is the concentration of vacancies. represents the surface gradient operator (the gradient operator with the component normal to the grain boundary removed). Conservation of mass can be written as where δ is the grain boundary thickness. The factor of 1/2 arises because each grain boundary borders two grains. Substitution of (34) into (35) yield the governing equation where represents the surface Laplacian operator. Equation (36) has to be supplemented by boundary conditions at the junctions where grain boundaries meet. Combining (36) with (24) and (25) leads to the following problems for the tensors and , and
Rivulet formulation in the flow of film down a uniformly heated vertical substrate
Published in Engineering Applications of Computational Fluid Mechanics, 2019
Meng Wang, Jiahui Zhao, Riqiang Duan
The heat flux imposed on the film flow is correlated with the Marangoni number, which measures the surface gradient of the surface tension resulting from the heterogeneous distribution of the surface temperature. For the heat flux boundary conditions on the substrate wall, the temperature difference scale, , is related to the heat flux imposed on the film flow, as shown in Eq. (1) The surface tension of the film liquid is σ = σa−γ (T−Ta) where σa is the surface tension at the ambient temperature Ta, and is the temperature dependence of the surface tension of the film liquid.
Automated image segmentation of air voids in hardened concrete surface using photometric stereo method
Published in International Journal of Pavement Engineering, 2022
Jueqiang Tao, Haitao Gong, Feng Wang, Xiaohua Luo, Xin Qiu, Yaxiong Huang
The normal map method assumes that the air voids have a sharper surface gradient and the concrete surface has a flatter surface gradient. Therefore, the pixels in the normal map that have a small could be concrete surface and the pixels in the normal map that have a large could be air voids. The relationship between Nt, Nxoy and is shown in Figure 3.