Augmented resolution of linear hyperbolic systems under nonconservative form

Hyperbolic systems under nonconservative form arise in numerous applications modeling physical processes, for example from the relaxation of more general equations (e.g. with dissipative terms). This paper reviews an existing class of augmented Roe schemes and discusses their application to linear nonconservative hyperbolic systems with source terms. We extend existing augmented methods by redefining them within a common framework which uses a geometric reinterpretation of source terms. This results in intrinsically well-balanced numerical discretizations. We discuss two equivalent formulations: (1) a nonconservative approach and (2) a conservative reformulation of the problem. The equilibrium properties of the schemes are examined and the conditions for the preservation of the well-balanced property are provided. Transient and steady state test cases for linear acoustics and hyperbolic heat equations are presented. A complete set of benchmark problems with analytical solution, including transient and steady situations with discontinuities in the medium properties, are presented and used to assess the equilibrium properties of the schemes. It is shown that the proposed schemes satisfy the expected equilibrium and convergence properties

Shallow water equations with depth-dependent anisotropic porosity for subgrid-scale topography

This paper derives a novel formulation of the depth-averaged shallow water equations with anisotropic porosity for computational efficiency reasons. The aim is to run simulations on coarser grids while maintaining an acceptable accuracy through the introduction of porosity terms, which account for subgrid-scale effects. The porosity is divided into volumetric and areal porosities, which are assigned to the cell volume and the cell edges, respectively. The former represents the volume in the cell available to flow and the latter represents the area available to flow over an edge, hence introducing anisotropy. The porosity terms are variable in time in dependence of the water elevation in the cell and the cumulative distribution function of the unresolved bottom elevation. The main novelty of the equations is the formulation of the porosities which enables full inundation of the cell. The applicability of the equations is verified in five computational examples, dealing with dam break and rainfall-runoff simulations. Overall, good agreement between the model results and a high-resolution reference simulation has been achieved. The computational time decreased significantly: on average three orders of magnitude

A Novel Slope Failure Operator for a Non-Equilibrium Sediment Transport Model

Complex transport mechanism and interaction between fluid and sediment make the mathematical and numerical modeling of sediment transport very challenging. Different types of models can lead to different results. This paper investigates a non-equilibrium sediment transport model based on the total load. In this type of model, it is assumed that a bed slide will occur if the bed slope reaches a critical angle. This is enabled by means of a slope failure operator. Existing slope failure operators usually suffer from the high computational cost and may fail at wet/dry interfaces. The main contribution of this work is the development of a novel slope failure operator for the total load transport model, based on a modified mass balance approach. The proposed approach is verified in three test cases, involving bank failure, dyke overtopping and a two-dimensional bank failure. It is shown that the proposed approach yields good agreement with analytical results and measurement data

High Resolution Simulation of Surface Water Flow in Natural Catchment Areas

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Lıpoma and ıncomplete agenesıs of the corpus callosum assocıated wıth arachnoıd cyst located ın the temporal pole: case report

This is a rare case of corpus callosum lipoma appearing with an intracranial arachnoid cyst located in the temporal pole. This case has been incidentally diagnosed by cranial computerized tomography and magnetic resonance imaging

Lıpoma and ıncomplete agenesıs of the corpus callosum assocıated wıth arachnoıd cyst located ın the temporal pole: Case report

This is a rare case of corpus callosum lipoma appearing with an intracranial arachnoid cyst located in the temporal pole. This case has been incidentally diagnosed by cranial computerized tomography and magnetic resonance imaging

Modeling Shallow Water Flow And Transport Processes With Small Water Depths Using The Hydroinformatics Modelling System

In hydro- and environmental systems modelling, there are several application cases where very small water depths occur, for example rainfall and runoff in natural or urban catchments, possibly associated with tracer transport. In these cases, the water depth may be in the range of millimeters to a few centimeters. The numerical simulation of the associated processes is complex, therefore robust numerical schemes are required. Two test cases using high resolution topography data are investigated with the Hydroinformatics Modelling System (HMS). In the first case, the influence of microtopography and local depressions were analyzed in an idealized urban catchment; both had a strong impact on the hydrograph. In the second one, rainfall runoff experiments, which were carried out by Mügler et al. [10] were simulated. Through parameter optimization an overall good agreement between computed and measured breakthrough curves was achieved

Simulation of Wind-Induced Flow and Transport in a Brazilian Bay

Experimental and Computational Hydraulic

Simulation of Flow and Transport Processes in a Brazilian Reservoir

Experimental and Computational Hydraulic

Understanding the hydrological response of a headwater-dominated catchment by analysis of distributed surface–subsurface interactions

We computationally explore the relationship between surface–subsurface exchange and hydrological response in a headwater-dominated high elevation, mountainous catchment in East River Watershed, Colorado, USA. In order to isolate the effect of surface–subsurface exchange on the hydrological response, we compare three model variations that differ only in soil permeability. Traditional methods of hydrograph analysis that have been developed for headwater catchments may fail to properly characterize catchments, where catchment response is tightly coupled to headwater inflow. Analyzing the spatially distributed hydrological response of such catchments gives additional information on the catchment functioning. Thus, we compute hydrographs, hydrological indices, and spatio-temporal distributions of hydrological variables. The indices and distributions are then linked to the hydrograph at the outlet of the catchment. Our results show that changes in the surface–subsurface exchange fluxes trigger different flow regimes, connectivity dynamics, and runoff generation mechanisms inside the catchment, and hence, affect the distributed hydrological response. Further, changes in surface–subsurface exchange rates lead to a nonlinear change in the degree of connectivity—quantified through the number of disconnected clusters of ponding water—in the catchment. Although the runoff formation in the catchment changes significantly, these changes do not significantly alter the aggregated streamflow hydrograph. This hints at a crucial gap in our ability to infer catchment function from aggregated signatures. We show that while these changes in distributed hydrological response may not always be observable through aggregated hydrological signatures, they can be quantified through the use of indices of connectivity