Guus S. Stelling

• Professor
• Delft University of Technology

The widespread availability of high-resolution Digital Elevation Models (DEM), has led to the development of subgrid numerical modelling techniques, based on Shallow Water Equations (SWE). Detailed DEM data is clustered as much as possible within a coarse grid cell that is preferably much larger than a raster pixel. This has considerable advantages...

The established method for determining dike heights and dimensioning river training structures is to assess the resulting backwater by numerical modelling. The common consensus is that bottom friction determines the backwater and that momentum advection only has a local effect. We demonstrate that the numerical/artificial backwater contribution fro...

A new numerical method for particle tracking (Lagrangian particle advection) on 2-D unstructured grids with triangular cells is presented and tested. This method combines key attributes of published methods, including streamline closure for steady flows and local mass conservation (uniformity preservation). The subgrid-scale velocity reconstruction...

We present a new modelling strategy for improving the efficiency of computationally intensive flow problems in environmental free-surface flows. The approach combines a recently developed semi-implicit subgrid method with a hierarchical-grid solution strategy. The method allows the incorporation of high-resolution data on subgrid scale to obtain a...

To improve the accuracy and the efficiency of morphodynamic simulations, we present a subgrid based approach for a morphodynamic model. This approach is well suited for areas characterized by sub-critical flow, like in estuaries, coastal areas and in low land rivers. This new method uses a different grid resolution to compute the hydrodynamics and...

Developing strategies to mitigate or to adapt to the threats of floods is an important topic in the context of climate changes. Many of the world’s cities are endangered due to rising ocean levels and changing precipitation patterns. It is therefore crucial to develop analytical tools that allow us to evaluate the threats of floods and to investiga...

hydrodynamic z-layer models, which are used for simulating the flow in rivers, estuaries, and oceans, suffer from an inaccurate and often discontinuous bottom shear stress representation, due to the staircase bottom. We analyze the governing equations and clearly show the cause of the inaccuracies. Based on the analysis, we present a new method tha...

In this paper, a semi‐implicit numerical model for one‐dimensional urban drainage networks is formulated in such a fashion as to intrinsically account for arbitrary cross sections, for the occurrence of dry areas, for free surface, and for pressurized flows. The governing differential equations are discretized with a consistent mass conservative sc...

[1] This study presents a finite volume hydrodynamic model for shallow water flow that computes on a coarse grid, but accounts for high-resolution bathymetry and roughness variations on a subgrid. The detailed information can be incorporated by using the assumption of a uniform flow direction and a uniform friction slope within a part of a coarse-g...

In this paper we explore the role of the river runoff , the tidal regime and the local winds in the dynamics of the Ria de Arousa estuary during the summer period, using for that purpose the numerical model Delft3D. First of all, a simulation under real hydrological and meteorological conditions is conducted in order to validate the ability of the...

The energy dissipation in the surf-zone due to wave breaking is inherently accounted for in shock-capturing non-hydrostatic wave models, but this requires high vertical resolutions. To allow coarse vertical resolutions a hydrostatic front approximation is suggested. It assumes a hydrostatic pressure distribution at the front of a breaking wave whic...

Particle-tracking models are often used for near field short-term subgrid transport of substances. The consistency demand at the discrete level does not show up so dominantly for these applications. This demand refers to the use of a numerical advection scheme for particles that is fully compatible with the local mass conserving advection propertie...

The International Conference on Coastal Engineering (ICCE) is a biennial conference held under the auspices of the Coastal Engineering Research Council of the COPRI (Coasts, Oceans, Ports, Rivers Institute) of the American Society of Civil Engineers. The Proceedings of the ICCE are provided here, with papers covering a wide range of topics includin...

It is now clear that the 2011 Tohoku-Oki earthquake ruptured the subduction interface all the way to the Japan Trench. However, there is significant disagreement about just how much slip occurred at the trench, with most geodetic studies locating only a small fraction of the maximum slip there, whereas broadband seismic studies put the majority of...

Flooding is an increasing hazard to society and good governance now implies careful water management in terms of design, planning and control of urban and rural areas. This requires that rainstorms, extreme water levels and so on are taken into account with relevant precision. A great aid is the existence of graphical information systems with raste...

We present a z-layer unstructured C-grid finite volume hydrostatic model. An efficient and highly scalable implicit technique for solution of the free surface equation is combined with an Eulerian approach for the advection of momentum. We show that an accurate velocity reconstruction procedure is of crucial importance not only for discretization o...

Bottom friction plays an important role in modelling river flows. In three-dimensional (3D) models, the vertical discretization is commonly based on σ-layers or z-layers. In this paper we focus on a well-known problem encountered when applying z-layers: local truncation errors in the computation of bottom shear stress and near-bed turbulence along...

Flood propagation models are essential to study floods as it is problematic to collect data during actual floods. Moreover, models are needed to explore the consequences of additional scenarios above the actual flood itself. The results of these model studies are generally graphs with water levels over time for certain locations or maps with the fl...

In this paper, a semi-implicit numerical model for two- and three-dimensional free-surface flows will be formulated in such a fashion as to intrinsically account for subgrid bathymetric details. It will be shown that with the proposed subgrid approach the model accuracy can be substantially improved without increasing the corresponding computationa...

A computational procedure has been developed for simulating non-hydrostatic, free-surface, rotational flows in one and two horizontal dimensions. Its implementation in the publicly available SWASH (an acronym of Simulating WAves till SHore) is intended to be used for predicting transformation of surface waves and rapidly varied shallow water flows...

No abstract available.

In this paper, a shallow-water flow solver is presented, based on the finite-volume method on unstructured grids The method is suitable for flows that occur in rivers, channels, sewer systems (1D), shallow seas, rivers, overland flow (2D), and estuaries, lakes and shelf breaks (3D). We present an outline of the numerical approach and show three 2D...

A new unstructured grid, finite volume ocean model, H2Ocean, is described, that is suitable for flooding and drying problems. Here we derive the finite volume analogue of the P1NC-P1 finite element, by interpreting the advective term in the continuity equation in a flux sense. A corresponding non-overlapping control volume is then selected for the...

In this paper, we focus on a conservative momentum advection discretisation in the presence of z-layers. While in the 2D case conservation of momentum is achieved automatically for an Eulerian advection scheme, special attention is required in the multi-layer case. We show here that an artificial vertical structure of the flow can be introduced sol...

The Indian Ocean Tsunami on December 26, 2004 caused one of the largest tsunamis in recent times and led to widespread devastation and loss of life. One of the worst hit regions was Banda Aceh, which is the capital of the Aceh province, located in the northern part of Sumatra, 150km from the source of the earthquake. A German-Indonesian Tsunami Ear...

The unstructured-mesh SWAN spectral wave model and the ADCIRC shallow-water circulation model have been integrated into a tightly-coupled SWAN + ADCIRC model. The model components are applied to an identical, unstructured mesh; share parallel computing infrastructure; and run sequentially in time. Wind speeds, water levels, currents and radiation s...

In open water systems, keeping both water depths and water quality at specified values is critical for maintaining a 'healthy' water system. Many systems still require manual operation, at least for water quality management. When applying real-time control, both quantity and quality standards need to be met. In this paper, an artificial polder flus...

The accuracy of nearshore infragravity wave height model predictions has been investigated using a combination of the spectral short wave evolution model SWAN and a linear 1D SurfBeat model (IDSB). Data recorded by a wave rider located approximately 3.5km from the coast at 18m water depth have been used to construct the short wave frequency-directi...

The Arakawa C-grid is in widespread use in structured grid atmospheric and oceanic models. It now forms the grid of choice for a number of efficient and compact unstructured grid codes. In order to calculate the Coriolis terms, the C-grid requires the interpolation of the tangential velocities. In the case of a finite volume and or finite differenc...

In this paper a layer-structured finite volume model for non-hydrostatic 3D environmental free surface flow is presented and applied to several test cases, which involve the computation of gravity waves. The 3D unsteady momentum and mass conservation equations are solved in a collocated grid made of polyhedrons, which are built from a 2D horizontal...

A numerical method for free-surface flow is presented to study water waves in coastal areas. The method builds on the nonlinear shallow water equations and utilizes a non-hydrostatic pressure term to describe short waves. A vertical boundary-fitted grid is used with the water depth divided into a number of layers. A compact finite difference scheme...

live/pagina.jsp?id=f928097d-81bb-4042-971b-e028c00e3326&lang=en LONG-TERM GOALS Our long-term goal is to provide the international community with the capability to determine the hydro-dynamic regimes of coastal environments (including large-scale catastrophic flooding) at the highest level, both operationally, with open source computer codes suppor...

A numerical method for non-hydrostatic, free-surface, irrotational flow governed by the nonlinear shallow water equations including the effects of vertical acceleration is presented at the aim of studying surf zone phenomena. A vertical boundary-fitted grid is used with the water depth divided into a number of layers. A compact finite difference sc...

This article introduces a new semi‐implicit, staggered finite volume scheme on unstructured meshes for the modelling of rapidly varied shallow water flows. Rapidly varied flows occur in the inundation of dry land during flooding situations. They typically involve bores and hydraulic jumps after obstacles such as road banks. Near such sudden flow tr...

The hydraulics in ozone systems, characterized by the residence time distribution, are investigated numerically as well as experimentally. The complex geometry of the ozone contactors requires the application of computational fluid dynamics (CFD), which in combination with experimental results gives insight in the hydraulic processes. Particle trac...

The symmetry and stability properties of two unstructured C-grid discretisations of the shallow water equations are discussed. We establish that a scheme in which the circumcentres of the mesh triangles are used as the surface elevation points has advantageous symmetry properties and derive a Coriolis discretisation which preserves these properties...

To understand the role of the co-seismic moment magnitude, Mw, 9.1–9.3 Sumatra–Andaman Earthquake rupture mechanism on the severity of the Indian Ocean Tsunami, we used permanent Global Positioning System (GPS) data and carried out an analysis of co-seismic displacement and tsunami models. Tsunami modelling, validated against independent Jason-1 al...

The coupling of flow and transport solvers we are dealing with in this paper represents a whole intermediate processing step taking place between the two. We develop new techniques to ensure mass conservation of the transport while using totally different numerical schemes in the flow and in the transport solvers. We also present a method which all...

Distributed temperature data are used as input and as calibration data for an energy based temperature model of a first order stream in Luxembourg. A DTS (Distributed Temperature Sensing) system with a fiber optic cable of 1500 m was used to measure stream water temperature with 1 m resolution each 2 min. Four groundwater inflows were identified an...

Highly distributed temperature data are used as input and as calibration data for a temperature model of a first order stream in Luxembourg. A DTS (Distributed Temperature Sensing) fiber optic cable with a length of 1500 m is used to measure stream water temperature with a spatial resolution of 0.5 m and a temporal resolution of 2 min. With the obs...

The chapter presents parallelization of an inundation model. The chapter focuses on parallelization of the matrix solver that combines a direct Gaussian elimination method with the iterative conjugate gradient algorithm. It is similar to the reduced system conjugate gradient method, and it is applicable not only to the problems that allow a red-bla...

In rivers, the phenomenon of flow separation past obstacles often gives rise to large-scale coherent structures. This study focuses on quasi-2d coherent structures associated with shallow flow separation (vortex shedding). New insights about the physical mechanism governing vortex shedding have been obtained from largescale Particle Image Velocimet...

A new scheme for the construction on an unstructured grid of the streamlines of the three-dimensional shallow water equations is presented. The qualitative advantages of the scheme, notably closed streamlines and realistic treatment of closed boundaries, are derived and the spatial accuracy is demonstrated.Semi-Lagrangian advection schemes offer th...

This contribution describes the state of the art of numerical flood simulation, in particular, the models based upon hydraulic laws. Both theory and practical aspects are discussed. In the introduction, various types of applications of these models are listed with their requirements in terms of robustness, accuracy, speed of operation, and engineer...

We present an unstructured grid finite volume three-dimensional hydrostatic model. An important aspect in 3D models is the choice of horizontal discretisation. For problems that are governed by complex coastal boundaries an unstructured grid approach seems attractive. This paper focuses on the development of a new unstructured grid three-dimensiona...

Nowadays the simulation of free surface flow and transport in rivers, estuaries and seas is often based upon three-dimensional modelling systems. Most of these three-dimensional modelling systems use sigma co-ordinates in the vertical. By the use of the sigma transformation the water column can be divided into the same number of layers independentl...

A semi-implicit, staggered finite volume technique for non-hydrostatic, free-surface flow governed by the incompressible Euler equations is presented that has a proper balance between accuracy, robustness and computing time. The procedure is intended to be used for predicting wave propagation in coastal areas. The splitting of the pressure into hyd...

Computer modeling of sediment transport patterns is generally recognized as a valuable tool for understanding and predicting morphological developments. In practice, state-of-the-art computer models are one- or two-dimensional (depth-averaged) and have a limited ability to model many of the important three-dimensional flow phenomena found in nature...

Flooding due to the failure of a dam or dyke has potentially disastrous consequences. This paper presents a Godunov-type finite volume solver of the shallow water equations based on dynamically adaptive quadtree grids. The Harten, Lax and van Leer approximate Riemann solver with the Contact wave restored (HLLC) scheme is used to evaluate interface...

This paper presents the capabilities and important features of Sobek-Rural and Sobek-Urban model. Sobek-Rural and Sobek-Urban, both developed by WL|DELFT HYDRAULICS, are integrated numerical hydraulic modeling packages to simulate hydrodynamics of one-dimensional (1D) river/channel/sewerage network and two-dimensional (2D) overland/street flow. Sob...

This paper proposes a numerical technique that in essence is based upon the classical staggered grids and implicit numerical integration schemes, but that can be applied to problems that include rapidly varied flows as well. Rapidly varied flows occur, for instance, in hydraulic jumps and bores. Inundation of dry land implies sudden flow transition...

A numerical technique is presented for the approximation of vertical gradient of the non-hydrostatic pressure arising in the Reynolds-averaged Navier–Stokes equations for simulating non-hydrostatic free-surface flows. It is based on the Keller-box method that take into account the effect of non-hydrostatic pressure with a very small number of verti...

The inundation model Delft flooding system (Delft-FLS) was applied to simulating the historical flood of 1805 in the polder Land van Maas en Waal (Netherlands). Delft-FLS is a two-dimensional (2-D) hydrodynamic model that simulates overland flow. Sensitivity analyses show a large influence of floodplain topography and hydraulic friction on the prop...

An new unstructured semi-implicit finite volume model is presented that solves the three-dimensional hydrostatic primitive equations. The model is shown to be suitable for simulations of shelf sea dynamics and its future suitability as a basis for operational work is argued. The current generation of oceanic and coastal flow models typically employ...

A new unstructured semi-implicit finite volume ocean model is presented that solves the three-dimensional hydrostatic primitive equations. The suitability of the model for the simulation of coastal and shelf seas is demonstrated through the example of simulations of the North Sea. Coastal flows are dominated by cross-shore flows in approximate geos...

Growing population and economic activities near rivers have increased the need for disaster management and flooding damage assessment. Reliable predictions of the hydrodynamics of flooding events provide a useful aid to fulfill these tasks. These predictions can be used during landscape, infrastructure and urban planning phases as well. The 2D-hydr...

In this paper we present a new vertical approximation of the non-hydrostatic pressure based on a Box method. It makes it possible to take into account the effect of the non-hydrostatic pressure with a very small number of layers (1–3). Also for a one layer depth-averaged model the results improve and are for short free surface waves comparable with...

The present paper describes a cyclone wind model and storm surge and flooding model for the east coast of India. They form part of the operational Storm Surge and Flood Forecast System that was recently developed and implemented in India. Results from these models are used to produce flood maps and potential wind damage maps with the help of GIS la...

A numerical method to solve the Reynolds-averaged Navier–Stokes equations with the presence of discontinuities is outlined and discussed. The pressure is decomposed into the sum of a hydrostatic component and a hydrodynamic component. The numerical technique is based upon the classical staggered grids and semi-implicit finite difference methods app...

Modeling capabilities for shallow, vegetated, systems are reviewed to assess hydrodynamic, wind and wave, submersed plant friction, and sediment transport aspects. Typically, ecosystems with submersed aquatic vegetation are relatively shallow, physically stable and of moderate hydrodynamic energy. Wind-waves are often important to sediment resuspen...

Open-check darns are built in mountain streams to control sediment transport during a flood. Sediment passes through them at the lowest discharges, whereas deposition occurs during the highest discharges. Open-check dams are currently designed based mainly on construction experience. Modeling of hydraulics and bed morphology in check darns involves...

This paper presents the application of a new software tool for modellingfluvial and floodplain hydraulics. The software package, developed by WL | Delft Hydraulics, integrates a one-dimensional (ID) modelling package known as SOBEK-Flow with a two-dimensional (2D) hydrodynamic prediction package known as Delft-FLS (Delft Flooding System). In the co...

In this paper two 3D shallow-water models are presented, using different vertical coordinate systems. The first one uses σ-coordinates (Phillips, 1957), the second one z-coordinates. Numerical problems related to both vertical coordinate systems are discussed. Improvements to minimize the numerical errors related to these problems are presented. Th...

Three-dimensional computations of a homogeneous shallow-water cavity flow in a square harbor were carried out. The turbulent flow was driven by a stationary current in an adjacent model river. The standard single-length-scale k-ε turbulence was found to underestimate the effective horizontal eddy viscosity in the mixing layer. To model the nonisotr...

Numerical models that assume hydrostatic pressure are usually sufficiently accurate for applications in civil engineering where the vertical component of the velocity is relatively small. Nevertheless, the vertical momentum, and, hence, the nonhydrostatic pressure component, cannot be neglected when the bottom topography of the domain changes abrup...

The ecological condition of the Continental Shelf is of great concern for many countries. The understanding of the integrated effects that result in the present and future situation requires answers on many research topics, such as flow modelling, including turbulence and large eddy simulation, transport processes, chemistry, ecology, etc. This pap...

This paper deals with the implementation of a domain decomposition method for the three-dimensional shallow water equations. The domain decomposition method belongs to the class of generalized additive Schwarz methods. It is based on a local coupling mechanism that allows for a flexible formulation of subdomain interfaces. For a real-life applicati...

This paper deals with the implementation of a multi block method for the three-dimensional shallow water equations. A multi block datastructure is incorporated into the Alternating Operator Implicit (AOI) method. In this research the computational domain is partitioned into a limited number of blocks c.q. subdomains. Application of the multi block...

In this report, transport problems are solved with a particle method that takes into account the Eulerian background flow field. Dispersion and other transport problems can be solved applying this model, as long as the corresponding transport process is formulated with a flux gradient relation, i.e., the advection-diffusion equation. The particle m...

Often industrial codes for the numerical integration of the 2D shallow water equations are based on an Alternating Direction Implicit method. However, for large time steps these codes suffer from inaccuracies when dealing with a complex geometry or bathymetry. This reduces the performance considerably. In this paper a new method is presented in whi...

Alternating Direction Implicit (ADI) methods are widely used for the approximation of shallow water equations. For calibration the size of the timestep is often based upon the so-called propagation factor. This factor gives only a minor indication of the numerical propagation speed of the tidal wave. It is shown that the numerical propagation speed...

An unsteady, separating, flume flow with a free surface was investigated with a physical model and a numerical model. To simulate tidal flow, the prescribed flow rate at the inflow boundary was a half-period sine function of time. Velocities and wave heights were measured by a laser Doppler velocimeter and a wave-height meter in a straight open cha...

Stability conditions of Dronkers' explicit finite difference schemes for tidal computations in rivers and open channels are derived. In addition to the CFL condition, more stringent stability conditions are found.

In order to come to a prediction of the performance of disinfection installations, CFD modelling can be a useful tool. To that end, a number of submodels needs to be solved. A flow model solves the underlying velocity fields. Particle tracks can be calculated by a particle tracking routine, which uses the information from the flow model. The disinf...

Concerns a coupling method between existing one- and two-dimensional horizontal flow models. A scheme based upon characteristic equations was found to give the most accurate results. (from paper)

Convective or advective processes play a role in many models for civil engineering applications. For example in transport equations, in hydrodynamic equations or wave energy equations. In this paper, we will first describe the requirements for the civil engineering practice and subsequently introduce the principles of cyclic computation and the use...

Paper presented at The Seventh International Conference on HydroScience and Engineering (ICHE) hosted by the College of Engineering at Drexel Univeristy on September 10-13, 2006 in Philadelphia, Pennsylvania. The conference theme was IT in the Field of HydroSciences. It included several mini-symposia that emphasized IT topics in HydroSciences and t...

Paper presented at The Seventh International Conference on HydroScience and Engineering (ICHE) hosted by the College of Engineering at Drexel Univeristy on September 10-13, 2006 in Philadelphia, Pennsylvania. The conference theme was IT in the Field of HydroSciences. It included several mini-symposia that emphasized IT topics in HydroSciences and t...

Flows in closed channels, such as rain storm sewers, often contain transitions from free surface flows to pressurized flows, or viceversa. These phenomena usually require two different sets of equations to model the two different flow regimes. Actually, a few specifications for the geometry of the channel and for the discretization choices can be s...