Establishing time-varying tidal and non-tidal water surface boundary conditions can improve typical year estimations for green infrastructure based Long-Term Control Plan wet-weather models

2018 ◽  
Vol 2018 (7) ◽  
pp. 5638-5654
Author(s):  
Eileen Althouse ◽  
Julie Midgette ◽  
Hao Zhang ◽  
Gary Martens
Keyword(s):  
Boundary Conditions ◽  
Green Infrastructure ◽  
Water Surface ◽  
Surface Boundary ◽  
Time Varying ◽  
Control Plan ◽  
Tidal Water ◽  
Surface Boundary Conditions ◽  
Wet Weather

A Comparative Study of Wave Breaking Models in a High-Order Spectral Model

2017 ◽  
Author(s):  
Betsy R. Seiffert ◽  
Guillaume Ducrozet
Keyword(s):  
Free Surface ◽  
Energy Dissipation ◽  
Boundary Conditions ◽  
Wave Breaking ◽  
Water Surface ◽  
Eddy Viscosity ◽  
Breaking Waves ◽  
Surface Boundary ◽  
Diffusion Term ◽  
Surface Boundary Conditions

We examine the implementation of two different wave breaking models into the nonlinear potential flow solver HOS-NWT. HOS-NWT is a computationally efficient, open source code that solves for surface elevation in a numerical wave tank using the High-Order Spectral (HOS) method [1]. The first model is a combination of a kinematic wave breaking onset criteria proposed by Barthelemey, et al. [2] and validated by Saket, et al. [3], and an energy dissipation mechanism proposed by Tian, et al. [4, 5]. The wave breaking onset parameter is based on the ratio of local energy flux velocity to the local crest velocity. Once breaking is initiated, an eddy viscosity parameter is estimated based on the pre-breaking local wave geometry, as described in [4, 5]. This eddy viscosity is then added as a diffusion term to the kinematic and dynamic free surface boundary conditions for the duration of wave breaking. Results implementing this wave breaking mechanism in HOS-NWT have shown that the model can successfully calculate the surface elevation and corresponding frequency spectra, as well as the energy dissipation associated with breaking waves [6–8]. The second model implemented to account for wave breaking in HOS-NWT is based on the method proposed by Chalikov, et al. [9–11]. This model defines wave breaking onset by the curvature of the water surface and defines the wave as broken if it exceeds a certain value. A diffusion term is added to the kinematic and dynamic free surface boundary conditions which dissipates energy based on the local curvature of the water surface, which is consequently not constant in space nor time. Calculations made using the two models are compared with large scale experimental measurements conducted at the Hydrodynamics, Energetics and Atmospheric Environment Lab (LHEEA) at Ecole Centrale de Nantes. Comparison of calculations with measurements suggest that both models are successful at predicting wave breaking onset and energy dissipation. However, the model proposed by Barthelemy, et al. [2] and Tian, et al. [4] can be applied without knowing anything about the breaking waves a priori, whereas the model proposed by Chalikov [9] requires tuning to specific conditions.

Modeling Active Layer Depth of Permafrost Changing Surface Boundary Conditions

2020 ◽  
Author(s):  
MODI ZHU ◽  
Jingfeng Wang ◽  
Husayn Sharif ◽  
Valeriy Ivanov ◽  
Aleksey Sheshukov
Keyword(s):  
Boundary Conditions ◽  
Active Layer ◽  
Surface Boundary ◽  
Layer Depth ◽  
Surface Boundary Conditions

scholarly journals Energy Pile Field Simulation in Large Buildings: Validation of Surface Boundary Assumptions

2019 ◽  
Author(s):  
Andrea Ferrantelli ◽  
Jevgeni Fadejev ◽  
Jarek Kurnitski
Keyword(s):  
Boundary Conditions ◽  
Single Point ◽  
Ground Surface ◽  
Thermal Mass ◽  
Heat Equations ◽  
Outlet Temperature ◽  
Surface Boundary ◽  
Geothermal Heat ◽  
Soil Medium ◽  
Surface Boundary Conditions

As the energy efficiency demands for future buildings become increasingly stringent, preliminary assessments of energy consumption are mandatory. These are possible only through numerical simulations, whose reliability crucially depends on boundary conditions. We therefore investigate their role in numerical estimates for the usage of geothermal energy, performing annual simulations of transient heat transfer for a building employing a geothermal heat pump plant and energy piles. Starting from actual measurements, we solve the heat equations in 2D and 3D using COMSOL Multiphysics and IDA-ICE, and discover a negligible impact of the multiregional ground surface boundary conditions. Moreover, we verify that the thermal mass of the soil medium induces a small vertical temperature gradient on the piles surface. We also find a roughly constant temperature on each horizontal cross-section, with nearly identical values if the average temperature is integrated over the full plane or evaluated at one single point. Calculating the yearly heating need for an entire building we then show that the chosen upper boundary condition affects the energy balance dramatically. Using directly the pipes’ outlet temperature induces a 54% overestimation of the heat flux, while the exact ground surface temperature above the piles reduces the error to 0.03%.

Novel free surface boundary conditions for spilling breaking waves

2020 ◽  
Vol 159 ◽  
pp. 103717
Author(s):  
Nikta Iravani ◽  
Peyman Badiei ◽  
Maurizio Brocchini
Keyword(s):  
Free Surface ◽  
Boundary Conditions ◽  
Breaking Waves ◽  
Surface Boundary ◽  
Surface Boundary Conditions
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