Abstract. The level set method allows for tracking material surfaces in 2-D and 3-D flow modeling and is well suited for applications of multi-material flow modeling. The level set method utilizes smooth level set functions to define material interfaces, which makes the method stable and free of oscillations that are typically observed in case step-like functions parameterize interfaces. By design the level set function is a signed distance function and gives for each point in the domain the exact distance to the interface as well as on which side it is located. In this paper we present four benchmarks which show the validity, accuracy and simplicity of using the level set method for multi-material flow modeling. The benchmarks are simplified setups of dynamical geophysical processes such as the Rayleigh-Taylor instability, post-glacial rebound, subduction and slab detachment. We also demonstrate the benefit of using the level set method for modeling a free surface with the sticky air approach. Our results show that the level set method allows for accurate material flow modeling and that the combination with the sticky air approach works well in mimicking Earth's free surface. Since the level set method tracks material interfaces instead of materials themselves, it has the advantage that the location of these interfaces is accurately known and that it represents a viable alternative to the more commonly used tracer method.

Abstract. The level set method allows for tracking material surfaces in 2-D and 3-D flow modeling and is well suited for applications of multi-material flow modeling. The level set method utilizes smooth level set functions to define material interfaces, which makes the method stable and free of oscillations that are typically observed in case step-like functions parameterize interfaces. By design the level set function is a signed distance function and gives for each point in the domain the exact distance to the interface and on which side it is located. In this paper we present four benchmarks which show the validity, accuracy and simplicity of using the level set method for multi-material flow modeling. The benchmarks are simplified setups of dynamical geophysical processes such as a Rayleigh–Taylor instability, post glacial rebound, subduction and slab detachment. We also demonstrate the benefit of using the level set method for modeling a free surface with the sticky air approach. Our results show that the level set method allows for accurate material flow modeling and that the combination with the sticky air approach works well in mimicking Earth's free surface. Since the level set method tracks material interfaces instead of materials themselves, it has the advantage that the location of these interfaces is accurately known and that it represents a viable alternative to the more commonly used tracer method.

<p>A common practice in Dutch and Flemish water utilities is to make masterplans for their network revisions and revise them on a regular basis, approximately every five years. The masterplans represent the ideal redesigns of their networks in terms of company specific objectives and constraints related to existing network infrastructure. The masterplans are used as a guideline when rehabilitating the networks. Among others, one of the objectives is to minimize the residence time, i.e., water age. However, the recurring assessment of water age with traditional methods, within an optimization procedure could take years for convergence for a large network of several thousand nodes. Consequently, the modellers often try to improve the residence time implicitly by minimizing network’s volume via layout optimization and diameter minimization, thus leading to increased velocities in pipes. Recently a graph theory model for estimating water age with satisfying accuracy has been proposed in the literature. The proposed model is estimated to be more than a hundred thousand times faster than the assessment of water age using Epanet, thus enabling the assessment of water age within optimization procedures. This research proposes a novel optimization methodology for simultaneous layout and pipe sizing optimization, employing the proposed graph-based model to explicitly assess the water age objective. To secure the reliability of the optimal solutions the methodology introduces a penalty to limit the size of the branched sections by setting a maximum to the number of customers connected to branched sections. The proposed methodology is applied to a real-world Dutch network. The aim of the research is to compare the optimal designs obtained using implicit (minimizing network’s volume) and new explicit (minimizing maximum water age) approaches.</p>

<p>In the past decades, the potential of numerical optimization for the automated design of drinking water distribution networks has been extensively studied. In particular, evolutionary algorithms have been shown to be a powerful and versatile tool for several design tasks. In the past few years in the Netherlands, drinking water utilities have started to embrace this approach more and more to explore new design philosophies as well as to address immediate asset management decision challenges. Key to meaningful application has been the possibility to iteratively and flexibly develop the optimization problem throughout the design process. The traditional 'benchmark problems' from academia provide a strong starting point for a design process, giving utility experts a taste of the possibilities. Subsequently, however, the problem definition has to be adapted and fine-tuned in order to keep up with the evolving perspective of the utility experts on the design problem. During this type of practical implementation, it frequently occurs that questions emerge which greatly increase the complexity of the optimization task without an approach being readily available from scientific literature, requiring workarounds to be created on the spot. Here, we present recent examples of such questions and their workarounds, which we ran into while tackling different practical design challanges, namely: how to incorporate topology optimization into regular pipe dimension optimization for a network in Belgium; how to incorporate topology and project cost optimization into sectorization of the network of The Hague; and how to incorporate optimal utilization of different water sources into regular pipe dimension optimization of the water distribution network of Amsterdam.</p>

In this research we investigated the influence of the heating of drinking water in the connection pipe under the influence of nearby district heating and the effect this has on water temperatures throughout the Domestic Drinking Water System (DDWS) of a typical Dutch domestic property. We found that stagnant water in the connection pipe warms up fast, reaching the surrounding ground temperature in about 15 minutes and these temperatures can be found throughout the house at taps such as the shower and the kitchen tap. Flowing water in the connection pipe is also, depending on the pipe length, heated up several degrees. The prevention of high temperatures in the soil around the connection pipe is the best measure to prevent high drinking water temperatures at the taps.