Modelling Flows in Pipes and Channels

A special issue of Fluids (ISSN 2311-5521).

Deadline for manuscript submissions: 31 December 2024 | Viewed by 3526

Special Issue Editor


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Guest Editor
Department of Mechanical Engineering and Mechatronics, West Pomeranian University of Technology Szczecin, Piastów 19, 70-310 Szczecin, Poland
Interests: water hammer; unsteady pipe flow; transient flow, cavitation; unsteady friction; retarded strain; numerical modelling; analytical solutions
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Special Issue Information

Dear Colleagues,

Welcome to the Special Issue on "Modelling Flows in Pipes and Channels". This issue serves as a comprehensive exploration of fluid flow dynamics within conduits, encompassing both steady-state and transient phenomena.

Fluid flows in pipes and channels are ubiquitous in hydraulic engineering, influencing various industrial, environmental, and infrastructure applications. Understanding the intricacies of these flows is paramount for optimizing system design, enhancing operational efficiency, and ensuring safety.

In this special issue, we aim to bridge the gap between steady-state and transient analyses, recognizing their symbiotic relationship in elucidating the complexities of fluid dynamics. Steady flow regimes provide foundational insights into the equilibrium states of fluid systems, offering invaluable benchmarks for comparison with transient events. Meanwhile, transient problems, characterized by sudden changes in flow rate, pressure, or other parameters, present unique challenges that demand sophisticated modelling techniques and precise numerical simulations.

We invite contributions that delve into mathematical formulations, boundary conditions, geometric influences, fluid properties, numerical techniques, and validation strategies pertinent to both steady and transient flow modelling. By embracing a holistic approach, we seek to advance our understanding of fluid flow dynamics in pipes and channels, facilitating the development of robust models and predictive tools.

Researchers and practitioners are encouraged to submit their work, encompassing theoretical advancements, experimental investigations, and practical applications. By fostering collaboration and knowledge exchange, this special issue aims to drive innovation in hydraulic engineering, ultimately leading to safer, more efficient, and sustainable fluid transport systems.

We're looking forward to your contributions and to the collective insights that will come from this interdisciplinary endeavor.

Dr. Kamil Urbanowicz
Guest Editor

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Keywords

  • transient flow
  • unsteady flow
  • numerical modelling
  • experimental research
  • frequency-dependent friction
  • cavitation
  • fluid-structure interaction FSI
  • leak detection
  • plastic pipes and channels
  • hydraulic losses

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Published Papers (5 papers)

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Research

18 pages, 3360 KiB  
Article
On the Modelling of Asymptotic Wavefronts in Long Ducts with Chambers
by Alan E. Vardy
Fluids 2024, 9(10), 240; https://doi.org/10.3390/fluids9100240 - 14 Oct 2024
Viewed by 357
Abstract
A novel method of determining the possible shapes of pressure wavefronts in ducts after they have travelled sufficient distances to evolve to asymptotic states is introduced. Although it is possible in principle to achieve the same outcome by simulating complete flow histories from [...] Read more.
A novel method of determining the possible shapes of pressure wavefronts in ducts after they have travelled sufficient distances to evolve to asymptotic states is introduced. Although it is possible in principle to achieve the same outcome by simulating complete flow histories from the time of the creation of the wavefronts, this can be impracticable. It is especially unsuitable to use such methods when extremely small grid lengths are needed to represent the final outcome adequately. The new method does not simulate the propagation phase at all. Instead, it explores what final end states are possible, but gives no information about the initiating disturbance or the wavefront evolution towards the assessed asymptotic state. Accordingly, the two methods do not overlap, but instead are complementary to each other. A typical case in which the new capability has high potential is described and used to illustrate the purpose and use of the methodology. However, the primary focus is on the presentation and assessment of the method, not on any particular phenomenon. It is shown that the required computational resources are far smaller than those needed for conventional unsteady flow simulations of propagating wavefronts. The potential numerical limitations of the method are highlighted and, with one exception, are shown to be either of no consequence or easily reduced to acceptable levels. Special attention is paid to the one exception because it cannot be proven to be unimportant and, indeed, it would be unsafe to use it in general analyses of wave propagation. However, strong evidence is presented of its acceptability for the study of asymptotic wavefronts. Full article
(This article belongs to the Special Issue Modelling Flows in Pipes and Channels)
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25 pages, 5876 KiB  
Article
Effects of Expelled Air during Filling Operations with Blocking Columns in Water Pipelines of Undulating Profiles
by Vicente S. Fuertes-Miquel, Oscar E. Coronado-Hernández and Alfonso Arrieta-Pastrana
Fluids 2024, 9(9), 212; https://doi.org/10.3390/fluids9090212 - 11 Sep 2024
Viewed by 405
Abstract
Entrapped air pockets can cause failure in water distribution systems if air valves have not been appropriately designed for expelling air during filling manoeuvres performed by water utilities. One-dimensional mathematical models recently developed for studying this phenomenon do not consider the effect of [...] Read more.
Entrapped air pockets can cause failure in water distribution systems if air valves have not been appropriately designed for expelling air during filling manoeuvres performed by water utilities. One-dimensional mathematical models recently developed for studying this phenomenon do not consider the effect of blocking columns inside water pipelines. This research presents the development of a mathematical model for analysing the filling process in a pipeline with an undulating profile with various air valves, including blocking columns during starting-up water installations. The results show how different air pocket pressure peaks can be produced over transient events, which need to be analysed to ensure a successful procedure that guarantees pipeline safety during the pressure surge occurrence. In this study, an experimental set-up is analysed to observe the behaviour of two blocking columns during filling by comparing the air pocket pressure pulses. Full article
(This article belongs to the Special Issue Modelling Flows in Pipes and Channels)
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17 pages, 911 KiB  
Article
Turbulent Micropolar Open-Channel Flow
by George Sofiadis, Antonios Liakopoulos, Apostolos Palasis and Filippos Sofos
Fluids 2024, 9(9), 202; https://doi.org/10.3390/fluids9090202 - 31 Aug 2024
Viewed by 409
Abstract
The present paper focuses on the investigation of the turbulent characteristics of an open-channel flow by employing the micropolar model. The underlying model has already been proven to correctly describe the secondary phase of turbulent wall-bounded flows. The open-channel case comprises an ideal [...] Read more.
The present paper focuses on the investigation of the turbulent characteristics of an open-channel flow by employing the micropolar model. The underlying model has already been proven to correctly describe the secondary phase of turbulent wall-bounded flows. The open-channel case comprises an ideal candidate to further test the micropolar model as many environmental flows carry a secondary phase, the behavior of which is of great interest for applications such as sedimentation transport and debris flow. Direct Numerical Simulations (DNSs) have been carried out on an open channel for Reb = 11,200 based on mean crossectional velocity, channel height, and the fluid kinematic viscosity. The simulated results are compared against previous experimental as well as Langrangian DNS data of similar flows, with excellent agreement. The micropolar model is capable of describing the same problem but in an Eulerian frame, thus significantly simplifying the computational cost and complexity. Full article
(This article belongs to the Special Issue Modelling Flows in Pipes and Channels)
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19 pages, 4859 KiB  
Article
Pressure and Velocity Profiles over a Weir Using Potential Flow Model
by M. R. Ajith Kumar, Prashanth R. Hanmaiahgari and Jaan H. Pu
Fluids 2024, 9(8), 182; https://doi.org/10.3390/fluids9080182 - 15 Aug 2024
Viewed by 624
Abstract
A potential flow model of the semi-inverse type is proposed to simulate flow over round crested weirs. This technique involves the construction of only streamlines over the weir instead of constructing the entire flow net. A Serre–Green–Naghdi (SGN) equation is employed to determine [...] Read more.
A potential flow model of the semi-inverse type is proposed to simulate flow over round crested weirs. This technique involves the construction of only streamlines over the weir instead of constructing the entire flow net. A Serre–Green–Naghdi (SGN) equation is employed to determine the initial free-surface profile, which is solved using a combined finite volume-finite difference scheme. The potential flow equations were numerically solved using a five-point central finite difference scheme. The model was applied to define the pressure and velocity fields in channel controls involving transcritical flow, such as the Gaussian weir, parabolic weir, and semicircular weir. The impact of streamline curvature on pressure and velocity distributions was investigated in the study. The curvature of the streamline strongly influenced the rise and drop of the bed pressures along the test section. A semicircular weir experiment was also conducted to validate the pressure and velocity profiles obtained using the proposed 2-D fluid flow model. The computed pressure and flow profiles from the solution of the potential flow equation agree perfectly with the present experiment and similar experiments available in the literature. In conclusion, the SGN equation provides an excellent initial profile to solve a 2-D ideal fluid flow numerically. Full article
(This article belongs to the Special Issue Modelling Flows in Pipes and Channels)
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19 pages, 6468 KiB  
Article
Minor Loss Coefficient for Abrupt Section Changes in a Cylindrical Pipe Using a Numerical Approach
by José González, Andrés Meana-Fernández, Iván Vallejo Pérez and Jesús M. Fernández Oro
Fluids 2024, 9(7), 152; https://doi.org/10.3390/fluids9070152 - 26 Jun 2024
Viewed by 1221
Abstract
Abrupt section changes are a classic problem in the study of flow in cylindrical ducts or pipes. For its analysis, there are a wide set of exiting data from previous studies, among which some authors stand out and will be mentioned. Those previous [...] Read more.
Abrupt section changes are a classic problem in the study of flow in cylindrical ducts or pipes. For its analysis, there are a wide set of exiting data from previous studies, among which some authors stand out and will be mentioned. Those previous works have been used to obtain reliable results for the resolution of section changes along a pipe, either due to cross area increases or reductions on a 1D basis. It is also known that a numerical 2D axisymmetric simulation (CFD) could find a consistent result compared to experimental data in almost all fluid flow fields. The main novelty of the present study is the development of a simple numerical approach used to solve the minor loss calculation. Firstly, a theoretical analysis is developed, and then the results of the numerical simulations carried out on the behavior that affects the water and air flow rate in an abrupt section change, for both contraction and expansion problems, are presented. In both cases, the results are analyzed with different meshes (discretizations) and turbulence models. Finally, the obtained numerical results are compared with those in the technical literature. Also, a theoretical approach is shown in order to show a whole frame of the discussion. The core results are the loss coefficient evolution as a function of the section change both for the sudden contraction and the expansion of a pipe flow. As the results follow the existing experimental values, it is concluded that the developed model provides a feasible and quick design tool to analyze possible geometrical changes without the need for further experiments. Full article
(This article belongs to the Special Issue Modelling Flows in Pipes and Channels)
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