arXiv subjects

Janice Lynn Ayog

Publications and source records attributed to Janice Lynn Ayog.

3 recordsLinked to original sources

arXiv2022

Shallow-flow velocity predictions using discontinuous Galerkin solutions

Numerical solvers of the two-dimensional (2D) shallow water equations (2D-SWE) can be an efficient option to predict spatial distribution of velocity fields in quasi-steady flows past or throughout hydraulic engineering structures. A second-order finite volume solver (FV2) spuriously elongates small-scale recirculating eddies within its predictions, unless sustained by an artificial eddy viscosity, while a third-order finite volume (FV3) solver can distort the eddies within its predictions. The extra complexity in a second-order discontinuous Galerkin (DG2) solver leads to significantly reduced error dissipation and improved predictions at a coarser resolution, making it a viable contender to acquire velocity predictions in shallow flows. This paper analyses this predictive capability for a grid-based, open source DG2 solver with reference to FV2 or FV3 solvers for simulating velocity magnitude and direction at the sub-meter scale. The simulated predictions are assessed against measured velocity data for four experimental test cases. The results consistently indicate that the DG2 solver is a competitive choice to efficiently produce more accurate velocity distributions for the simulations dominated by smooth flow regions.

physics.flu-dyn↗

arXiv2021

Well-resolved velocity fields using discontinuous Galerkin shallow water solutions

Computational models based on the depth-averaged shallow water equations (SWE) offer an efficient choice to analyse velocity fields around hydraulic structures. Second-order finite volume (FV2) solvers have often been used for this purpose subject to adding an eddy viscosity term at sub-meter resolution, but have been shown to fall short of capturing small-scale field transients emerging from wave-structure interactions. The second-order discontinuous Galerkin (DG2) alternative is significantly more resistant to the growth of numerical diffusion and leads to faster convergence rates. These properties make the DG2 solver a promising modelling tool for detailed velocity field predictions. This paper focuses on exploring this DG2 capability with reference to an FV2 counterpart for a selection of test cases that require well-resolved velocity field predictions. The findings of this work lead to identifying a particular setting for the DG2 solver that allows for obtaining more accurate and efficient depth-averaged velocity fields incorporating small-scale transients.

physics.flu-dyn↗

arXiv2020

Second-order discontinuous Galerkin flood model: comparison with industry-standard finite volume models

Finite volume (FV) numerical solvers of the two-dimensional shallow water equations are core to industry-standard flood models. The second-order Discontinuous Galerkin (DG2) alternative, although a viable way forward to improve current FV-based flood models, is yet under-studied and rarely used to support flood modelling applications. This paper systematically explores and compares the predictive properties of a robust DG2 flood model to those of prominent FV-based industrial flood models. To identify the simplest and most efficient DG2 configuration suitable for flood inundation modelling, two variants - with and without local slope limiting - are considered. The numerical conservation properties of the DG2 variants are compared to those of a first-order FV (FV1) and a second-order FV (FV2) counterparts. The DG2 variants are then tested over five realistic flooding scenarios, recommended by the UK Environment Agency to validate 2D flood model capabilities, while comparing their performance against that of four FV-based commercial models (i.e. TUFLOW-FV1, TUFLOW-FV2, TUFLOW-HPC and Infoworks ICM). Results reveal that the DG2 variant without local limiting (DG2-NL) is capable to simulate shockless flood flows featured in a wide range of flood modelling applications. The DG2-NL shows closer predictions to commercial model outputs at twice-coarser spatial resolution, and can run twice faster to produce more informative hydrograph with small-scale transients over long-range simulations, even when the sampling is far away from the flooding source.

physics.comp-ph↗