On modeling subgrid-scale macro-structures in narrow twisted channels

Li, Zhi; Hodges, Ben R.

doi:10.1016/j.advwatres.2019.103465

Title: On modeling subgrid-scale macro-structures in narrow twisted channels

Full Record
Other Related Research

Abstract

Porosity-based subgrid topography models often fail to capture the effects of subgrid-scale topographic features in the interior of coarse grid cells. Existing approaches that modify bottom roughness or a drag coefficient are inadequate for macro-structures (large emergent or submerged obstacles) in subgrid-scale narrow twisted channels. Such structures partially block the cross-sectional area and provide enhanced topographic dissipation – effects that are not well represented by a drag coefficient that scales on a coarse-grid cell-averaged velocity and the cell volume. The relative alignment between mesh and flow further complicates this problem as it makes the subgrid model sensitive to mesh design. In the present study, three new approaches for simulating subgrid-scale macro-structures in narrow channels are proposed. The interior partial-blocking effect of structures is modeled as reduction of grid face-area. The sheltering of flow volumes around obstacles, which leads to topographic dissipation, is modeled by reducing the cell volume in the momentum equation (only). A mesh-shift procedure is designed to optimize mesh alignment for identifiable subgrid features. Combining the three subgrid methods improves the approximation of surface elevation and in-channel flow rate with a coarse-grid model. Tests are conducted for channelized flow using both synthetic domains and real marsh topography. Finally,more »« less

Authors:

Li, Zhi ^[1]; Hodges, Ben R. ^[1]

Univ. of Texas, Austin, TX (United States)

Publication Date:: Wed Nov 13 00:00:00 EST 2019

Research Org.:: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:: USDOE Office of Science (SC)

OSTI Identifier:: 1634065

Grant/Contract Number:: AC02-05CH11231

Resource Type:: Accepted Manuscript

Journal Name:: Advances in Water Resources

Additional Journal Information:: Journal Volume: 135; Journal ID: ISSN 0309-1708

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 42 ENGINEERING; subgrid topography model; grid alignment; narrow twisted channel; subgrid macro-structures; topographic dissipation

Citation Formats


                    Li, Zhi, and Hodges, Ben R. On modeling subgrid-scale macro-structures in narrow twisted channels.  United States: N. p., 2019. 
Web.  doi:10.1016/j.advwatres.2019.103465.

Copy to clipboard


                    Li, Zhi, & Hodges, Ben R. On modeling subgrid-scale macro-structures in narrow twisted channels.  United States.  https://doi.org/10.1016/j.advwatres.2019.103465

Copy to clipboard


                    Li, Zhi, and Hodges, Ben R. Wed .  
"On modeling subgrid-scale macro-structures in narrow twisted channels".  United States.  https://doi.org/10.1016/j.advwatres.2019.103465.  https://www.osti.gov/servlets/purl/1634065.

Copy to clipboard


                    
@article{osti_1634065,

  title        = {On modeling subgrid-scale macro-structures in narrow twisted channels},

  author       = {Li, Zhi and Hodges, Ben R.},

  abstractNote = {Porosity-based subgrid topography models often fail to capture the effects of subgrid-scale topographic features in the interior of coarse grid cells. Existing approaches that modify bottom roughness or a drag coefficient are inadequate for macro-structures (large emergent or submerged obstacles) in subgrid-scale narrow twisted channels. Such structures partially block the cross-sectional area and provide enhanced topographic dissipation – effects that are not well represented by a drag coefficient that scales on a coarse-grid cell-averaged velocity and the cell volume. The relative alignment between mesh and flow further complicates this problem as it makes the subgrid model sensitive to mesh design. In the present study, three new approaches for simulating subgrid-scale macro-structures in narrow channels are proposed. The interior partial-blocking effect of structures is modeled as reduction of grid face-area. The sheltering of flow volumes around obstacles, which leads to topographic dissipation, is modeled by reducing the cell volume in the momentum equation (only). A mesh-shift procedure is designed to optimize mesh alignment for identifiable subgrid features. Combining the three subgrid methods improves the approximation of surface elevation and in-channel flow rate with a coarse-grid model. Tests are conducted for channelized flow using both synthetic domains and real marsh topography. Finally, the new methods reduce the overall mesh dependency of the subgrid model and provides stronger physical connection between effects of macro-structures and their geometry at coarse grid scales.},

  doi          = {10.1016/j.advwatres.2019.103465},

  journal      = {Advances in Water Resources},

  number       = ,

  volume       = 135,

  place        = {United States},

  year         = {Wed Nov 13 00:00:00 EST 2019},

  month        = {Wed Nov 13 00:00:00 EST 2019}

}

Copy to clipboard

Journal Article:

Free Publicly Available Full Text

Accepted Manuscript (DOE)

Publisher's Version of Record

https://doi.org/10.1016/j.advwatres.2019.103465

Other availability

Search WorldCat to find libraries that may hold this journal

Citation Metrics:

Cited by: 9 works

Citation information provided by
Web of Science

Save / Share:

Export Metadata

Save to My Library

Similar Records in DOE PAGES and OSTI.GOV collections:

Exploring topography-based methods for downscaling subgrid precipitation for use in Earth System Models

Journal Article Tesfa, Teklu K. ; Leung, Lai-Yung ; Ghan, Steven J. - Journal of Geophysical Research: Atmospheres

Topography exerts major control on land surface processes. To improve representation of topographic impacts on land surface processes, a new topography-based subgrid structure has been introduced to the Energy Exascale Earth System Model to represent the subgrid heterogeneity of surface elevation. To take advantage of the new subgrid structure for improving land surface modeling, this study explores four variations of topography-based methods for downscaling grid precipitation to the corresponding subgrids. In the first three methods, the deviation of the subgrid precipitation from the grid’s is equal to the grid precipitation multiplied by the ratio of the elevation difference between themore »« less
https://doi.org/10.1029/2019JD031456
Towards district scale flood simulations using conventional and anisotropic porosity shallow water models with high-resolution topographic information

Journal Article Özgen, Ilhan ; Abily, Morgan ; Zhao, Jiaheng ; ... - La Houille Blanche

Current topographic survey technology provides high-resolution (HR) datasets for urban environments. Incorporating this HR information in models aiming to provide flood risk assessment is desirable because the flood wave propagation is depending on the urban topographic features, i.e. buildings, bridges and street networks. Conceptual, numerical and practical challenges arise from the application of shallow water models to HR urban flood modeling. For example, numerical challenges are occurrence of wet-dry fronts, geometric discontinuities in the urban environment and discontinuous solutions, i.e. shock waves. These challenges can be overcome by using a Godunov-type scheme. However, the computational cost of this type ofmore »« less
https://doi.org/10.1051/lhb/2018023

Full Text Available
Subgrid-scale model for radiative transfer in turbulent participating media

Journal Article Soucasse, L. ; Rivière, Ph. ; École Centrale Paris, Grande Voie des Vignes, F-92290 Châtenay-Malabry ; ... - Journal of Computational Physics

The simulation of turbulent flows of radiating gases, taking into account all turbulence length scales with an accurate radiation transport solver, is computationally prohibitive for high Reynolds or Rayleigh numbers. This is particularly the case when the small structures are not optically thin. We develop in this paper a radiative transfer subgrid model suitable for the coupling with direct numerical simulations of turbulent radiating fluid flows. Owing to the linearity of the Radiative Transfer Equation (RTE), the emission source term is spatially filtered to define large-scale and subgrid-scale radiation intensities. The large-scale or filtered intensity is computed with a standardmore »« less
https://doi.org/10.1016/J.JCP.2013.10.006
On the effect of subgrid drag closures

Journal Article Benyahia, s - Ind. Eng. Chem. Res.

The effect of two subgrid drag closures on the flow of air and Geldart group A particles is presented in this study. A subgrid drag model based on fitting simulation data obtained from finely resolved simulations and a drag model based on the energy minimization approach are both used to solve a gas-solids flow in the riser section of a circulating fluidized bed. The numerical results using a coarse computational grid obtained with these subgrid models are compared with those using a standard drag model as well as experimental data obtained in a pilot-scale riser. Numerical predictions using both subgridmore »« less
Reducing impacts of artificial ponding in modeling salt marshes using a conductivity-formulated subgrid model

Journal Article Chen, Yujie ; Shi, Fengyan ; Kirby, James T. ; ... - Estuarine Coastal and Shelf Science

The landforms of salt marsh systems are rather complex, with meandering channel networks cutting through low-lying, extensive marsh platforms. Some small-scale topographic details are critical to flooding and draining processes but cannot be reflected in the Digital Elevation Model (DEM) due to limited measurement resolution and vegetation bias. Numerical models need a grid with high enough resolution to capture the small-scale connectivity to correctly model the small-scale flow processes, making the model computationally unaffordable. Here, in this study, we derived a subgrid model, which couples two flow components, one is the regular subgrid model for simulating the subgrid-resolved flows, andmore »« less
https://doi.org/10.1016/j.ecss.2023.108441

Similar Records