Even the best-maintained water distribution network (WDN) might suffer pipe bursts occasionally, and the utility company must reconstruct the damaged sections of the system. The affected area must be segregated by closing the corresponding isolation valves; as a result, the required amount of drinking water might not be available. This paper explores the behaviour and topology of segments, especially their criticality from the viewpoint of the whole system. A novel, objective, dimensionless, segment-based quantity is proposed to evaluate the vulnerability of both the segments and the whole WDN against a single, incidental pipe break, computed as the product of the probability of failure within the segment and the amount of unserved consumption. 27 comprehensive real-life WDNs have been examined by means of the new metric and with the help of complex network theory, exploiting the concept of the degree distribution and topology-based structural properties (e.g. network diameter, clustering coefficient). It was found that metrics based purely on topology suggest different network behaviour as vulnerability analysis, which also includes the hydraulics. The investigation of the global network vulnerabilities has revealed several critically exposed systems, and the local distributions unveiled new properties of WDNs in the case of a random pipe break.

The need to improve the accuracy of mathematical models describing hydraulic networks (e.g., water distribution systems) poses numerous challenges regarding the problems of parameter calibration and optimal sampling. In this paper, a comparison is made between different sensor placing strategies, including a novel, direct (iteration-free) algorithm. The approach used is based on maximizing both the sensitivity and the so-called hydraulic distance of the sampling points without the need for optimization. Based on these sampled measurements, the pipe roughness coefficient of each pipe is calibrated individually (without grouping) by solving the resulting underdetermined linear system with singular value decomposition. The efficiency of the approach is demonstrated on case studies, including artificial (e.g., Anytown and C-town) and real-life water distribution systems through detailed statistical comparison.

This study investigates the transient flow dynamics and pressure interactions within Tesla valve configurations through comprehensive CFD simulations. Tesla valves offer efficient passive fluid control without the need for external power, making them favorable in various applications. Previous observations indicated that Tesla valves effectively reduce the amplitude of pressure transients, prolonging their duration and distributing energy over an extended timeframe. While suggesting a potential role for Tesla valves as pressure dampers during transient events, the specific mechanisms behind this behavior remain unexplored. This research focuses on elucidating the internal dynamics of Tesla valves during transient events, aiming to unravel the processes responsible for the observed attenuation in pressure transients. This study reveals the emergence of “pressure pockets” within Tesla valves, deviating from conventional uniform pressure fronts. These pockets manifest as discrete chambers with varying lengths and volumes, contributing to the non-uniform propagation of pressure throughout the system. This investigation employs advanced CFD simulations as a crucial tool to unravel the governing dynamics of transient flow within Tesla valve configurations. By elucidating underlying fluid dynamics, this study lays the groundwork for future Tesla valve design optimization, holding potential implications for applications where the control of transient flow events is crucial.

Nowadays, the rapid growth of operational costs and human resource shortages increase the importance of the leakage reduction, and the pressure management. This paper presents an optimisation procedure placing pressure-reducing valves (PRVs) to minimise the water losses of real-life water distribution networks (WDNs). The number and placement of the valves are optimised from clustering perspective with the Leiden algorithm. The optimal settings of the valves are determined with a differential evolution algorithm, where a compound fitness function is applied. On the one hand, it minimises the leakages, on the other hand, evades the pressure-dependent consumer outages, i.e. it keeps the pressure above the desired. Seven real-life water distribution networks were analysed from the region of Western Hungary using the techniques. Moreover, three of them are analysed in details. The robustness of the achieved leakage reduction with the optimised PRV placement is analysed to the uncertainty of the leakage exponent.

Low‐dimensional (1D or 0D) models can describe the whole human blood circulation, for example, 1D distributed parameter model for the arterial network and 0D concentrated models for the heart or other organs. This paper presents a combined 1D‐0D solver, called first_blood, that solves the governing equations of fluid dynamics to model low‐dimensional hemodynamic effects. An extended method of characteristics is applied here to solve the momentum, and mass conservation equations and the viscoelastic wall model equation, mimicking the material properties of arterial walls. The heart and the peripheral lumped models are solved with a general zero‐dimensional (0D) nonlinear solver. The model topology can be modular, that is, first_blood can solve any 1D‐0D hemodynamic model. To demonstrate the applicability of first_blood, the human arterial system, the heart and the peripherals are modelled using the solver. The simulation time of a heartbeat takes around 2 s, that is, first_blood requires only twice the real‐time for the simulation using an average PC, which highlights the computational efficiency. The source code is available on GitHub, that is, it is open source. The model parameters are based on the literature suggestions and on the validation of output data to obtain physiologically relevant results.

This paper focuses on the hydrodynamic behavior of liquid pipelines in the presence of air valves. The aim of installing such valves on pipeline systems is twofold: on one hand, they release the accumulated air content and on the other hand, they allow the outer air to entrain the system when the internal pressure falls beneath ambient pressure (i.e. vacuum formation). We study the hydraulic transients in the presence of such air valve by means of experimental and numerical methods. The experiments were performed using a special test section where the pipeline close to the air valve was built from plexiglas allowing visual access. Furthermore, pressure signals were recorded at several locations of the pipeline. Numerical analysis was also performed using the commercially available CFD software (ANSYS CFX). It was revealed that the entrained air separates well from the primary liquid and the mixture behaves as two distinct phases.