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Energies
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The Numerical Simulation of Fluid Flow
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The Numerical Simulation of Fluid Flow

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A3: Wind, Wave and Tidal Energy".

Deadline for manuscript submissions: closed (1 September 2021) | Viewed by 36240

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Dr. Robert Castilla

E-Mail Website
Guest Editor
Department of Fluid Mechanics, Polytechnic University of Catalonia, Terrassa Campus, 08222 Barcelona, Spain
Interests: computational fluid dynamics; industrial applications of fluid flows; aeroacoustics; gas dynamics
Prof. Dr. Anton Vernet

E-Mail Website
Guest Editor
Department of Mechanical Engineering, Universitat Rovira i Virgili, ETSEQ Campus Sescelades, 432007 Tarragona, Spain
Interests: computational fluid dynamics; data analysis; industrial applications of fluid flows; experimental fluid dynamics; particle image velocimetry; image analysis

Special Issue Information

Dear Colleagues,

Almost every energy production process involves fluid flow. This ranges from the most obvious, like air through wind turbine blades or fuel flow in an internal combustion engine, to a secondary though still essential role like lubrication in a mechanical power transmission hub. In the last sixty years the simulation of fluid flows has been so relevant that CFD (computational fluid dynamics) has become a discipline that is included in any textbook of Fluid Mechanics. The growth of computing capacity, summarized in Moore’s law, and the development of numerical methodologies provide increasingly efficient and accurate simulations.

This Special Issue of Energies aims to focus on the practical application of available methodologies and models rather than the presentation of new numerical methods. Nevertheless, the submitted manuscripts must include proper treatment of methods and results. Both spatial and temporal numerical schemes must be clearly described, along with boundary conditions, geometry, and governing parameters (dimensionless numbers). Schemes should be at least second-order in space. Grid convergence analysis has to be discussed. Commercial, open source, and in-home codes can be used.

Topics of interest include, but are not limited to:

  1. Simulation of turbomachinery performance;
  2. Aerodynamics;
  3. Compressible flow: compressors, turbochargers, steam turbines, ejectors, etc.;
  4. Fluid flow in complex geometries: valves, pumps, motors, actuators, etc.;
  5. Multiphase flows: open channels (flumes, weirs, etc.), cavitation, bubbles, mist, annular flows, etc.;
  6. Air flow in wind turbines, buildings, etc.;
  7. HVAC (heating, ventilation, and air conditioning);
  8. Passive and active control of boundary layer detachment;
  9. Computational aeroacoustics;
  10. Microfluidics;
  11. Tribology;
  12. Rheology.

Prof. Dr. Robert Castilla
Prof. Dr. Anton Vernet
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • computational fluid dynamics
  • meshing
  • compressible flow
  • turbulence modeling
  • combustion

Published Papers (7 papers)

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Research

19 pages, 14483 KiB  
Article
An Immersed Boundary Method Based Improved Divergence-Free-Condition Compensated Coupled Framework for Solving the Flow–Particle Interactions
by Pao-Hsiung Chiu, Huei Chu Weng, Raymond Byrne, Yu Zhang Che and Yan-Ting Lin
Energies 2021, 14(6), 1675; https://doi.org/10.3390/en14061675 - 17 Mar 2021
Viewed by 1955
Abstract
A flow–particle interaction solver was developed in this study. For the basic flow solver, an improved divergence-free-condition compensated coupled (IDFC2) framework was employed to predict the velocity and pressure field. In order to model the effect of solid particles, the differentially [...] Read more.
A flow–particle interaction solver was developed in this study. For the basic flow solver, an improved divergence-free-condition compensated coupled (IDFC2) framework was employed to predict the velocity and pressure field. In order to model the effect of solid particles, the differentially interpolated direct forcing immersed boundary (DIIB) method was incorporated with the IDFC2 framework, while the equation of motion was solved to predict the displacement, rotation and velocity of the particle. The hydrodynamic force and torque which appeared in the equations of motion were directly evaluated by fluid velocity and pressure, so as to eliminate the instability problem of the density ratio close to 1. In order to effectively evaluate the drag/lift forces acting on the particle, an interpolated kernel function was introduced. The present results will be compared with the benchmark solutions to validate the present flow–particle interaction solver. Full article
(This article belongs to the Special Issue The Numerical Simulation of Fluid Flow)
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18 pages, 1040 KiB  
Article
Analysis of Aeroacoustic Properties of the Local Radial Point Interpolation Cumulant Lattice Boltzmann Method
by Mohsen Gorakifard, Clara Salueña, Ildefonso Cuesta and Ehsan Kian Far
Energies 2021, 14(5), 1443; https://doi.org/10.3390/en14051443 - 6 Mar 2021
Cited by 6 | Viewed by 1872
Abstract
The lattice Boltzmann method (LBM) has recently been used to simulate wave propagation, one of the challenging aspects of wind turbine modeling and simulation. However, standard LB methods suffer from the instability that occurs at low viscosities and from its characteristic lattice uniformity, [...] Read more.
The lattice Boltzmann method (LBM) has recently been used to simulate wave propagation, one of the challenging aspects of wind turbine modeling and simulation. However, standard LB methods suffer from the instability that occurs at low viscosities and from its characteristic lattice uniformity, which results in issues of accuracy and computational efficiency following mesh refinement. The local radial point interpolation cumulant lattice Boltzmann method (LRPIC-LBM) is proposed in this paper to overcome these shortcomings. The LB equation is divided into collision and streaming steps. The collision step is modeled by the cumulant method, one of the stable LB methods at low viscosities. In addition, the streaming step, which is naturally a pure advection equation, is discretized in time and space using the Lax–Wendroff scheme and the local radial point interpolation method (RPIM), a mesh free method. We describe the propagation of planar acoustic waves, including the temporal decay of a standing plane wave and the spatial decay of a planar acoustic pulse. The analysis of these specific benchmark problems has yielded qualitative and quantitative data on acoustic dispersion and dissipation, and their deviation from analytical results demonstrates the accuracy of the method. We found that the LRPIC-LBM replicates the analytical results for different viscosities, and the errors of the fundamental acoustic properties are negligible, even for quite low resolutions. Thus, this method may constitute a useful platform for effectively predicting complex engineering problems such as wind turbine simulations, without parameter dependencies such as the number of points per wavelength Nppw and resolution σ or the detrimental effect caused by the use of coarse grids found in other accurate and stable LB models. Full article
(This article belongs to the Special Issue The Numerical Simulation of Fluid Flow)
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21 pages, 5161 KiB  
Article
A Fast Two-Dimensional Numerical Method for the Wake Simulation of a Vertical Axis Wind Turbine
by Zheng Yuan, Jin Jiang, Jun Zang, Qihu Sheng, Ke Sun, Xuewei Zhang and Renwei Ji
Energies 2021, 14(1), 49; https://doi.org/10.3390/en14010049 - 24 Dec 2020
Cited by 8 | Viewed by 1943
Abstract
In the array design of the vertical axis wind turbines (VAWT), the wake effect of the upstream VAWT on the downstream VAWT needs to be considered. In order to simulate the velocity distribution of a VAWT wake rapidly, a new two-dimensional numerical method [...] Read more.
In the array design of the vertical axis wind turbines (VAWT), the wake effect of the upstream VAWT on the downstream VAWT needs to be considered. In order to simulate the velocity distribution of a VAWT wake rapidly, a new two-dimensional numerical method is proposed, which can make the array design easier and faster. In this new approach, the finite vortex method and vortex particle method are combined to simulate the generation and evolution of the vortex, respectively, the fast multipole method (FMM) is used to accelerate the calculation. Based on a characteristic of the VAWT wake, that is, the velocity distribution can be fitted into a power-law function, a new correction model is introduced to correct the three-dimensional effect of the VAWT wake. Finally, the simulation results can be approximated to the published experimental results in the first-order. As a new numerical method to simulate the complex VAWT wake, this paper proves the feasibility of the method and makes a preliminary validation. This method is not used to simulate the complex three-dimensional turbulent evolution but to simulate the velocity distribution quickly and relatively accurately, which meets the requirement for rapid simulation in the preliminary array design. Full article
(This article belongs to the Special Issue The Numerical Simulation of Fluid Flow)
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20 pages, 6505 KiB  
Article
Study of Surface Roughness Effect on a Bluff Body—The Formation of Asymmetric Separation Bubbles
by Alex Mendonça Bimbato, Luiz Antonio Alcântara Pereira and Miguel Hiroo Hirata
Energies 2020, 13(22), 6094; https://doi.org/10.3390/en13226094 - 20 Nov 2020
Cited by 13 | Viewed by 3237
Abstract
Turbulent flows around bluff bodies are present in a large number of aeronautical, civil, mechanical, naval and oceanic engineering problems and still need comprehension. This paper provides a detailed investigation of turbulent boundary layer flows past a bluff body. The flows are disturbed [...] Read more.
Turbulent flows around bluff bodies are present in a large number of aeronautical, civil, mechanical, naval and oceanic engineering problems and still need comprehension. This paper provides a detailed investigation of turbulent boundary layer flows past a bluff body. The flows are disturbed by superficial roughness effect, one of the most influencing parameters present in engineering applications. A roughness model, recently developed by the authors, is here employed in order to capture the main features of these complex flows. Starting from subcritical Reynolds number simulations (Re = 1.0 × 105), typical phenomena found on critical and supercritical flow regimes are successfully captured, like non-zero lift force and its direction change, drag crisis followed by a gradual increase on this force, and separation and stagnation points displacement. The main contribution of this paper is to present a wide discussion related with the temporal history of aerodynamic loads of a single rough circular cylinder capturing the occurrence of asymmetric separation bubbles generation. The formation of asymmetric separation bubbles is an intrinsic phenomenon of the physical problem, which is successfully reported by our work. Unfortunately, there is a lack of numerical results available in the literature discussing the problem, which has also motivated the present paper. Previous study of our research group has only discussed the drag crisis, without to investigate its gradual increase and the change on lift force direction. Our results again confirm that the Lagrangian vortex method in association with Large-Eddy Simulation (LES) theory enables the development of two-dimensional roughness models. Full article
(This article belongs to the Special Issue The Numerical Simulation of Fluid Flow)
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25 pages, 23532 KiB  
Article
Aerodynamic Study of the Wake Effects on a Formula 1 Car
by Alex Guerrero and Robert Castilla
Energies 2020, 13(19), 5183; https://doi.org/10.3390/en13195183 - 5 Oct 2020
Cited by 11 | Viewed by 19158
Abstract
The high complexity of current Formula One aerodynamics has raised the question of whether an urgent modification in the existing aerodynamic package is required. The present study is based on the evaluation and quantification of the aerodynamic performance on a 2017 spec. adapted [...] Read more.
The high complexity of current Formula One aerodynamics has raised the question of whether an urgent modification in the existing aerodynamic package is required. The present study is based on the evaluation and quantification of the aerodynamic performance on a 2017 spec. adapted Formula 1 car (the latest major aerodynamic update) by means of Computational Fluid Dynamics (CFD) analysis in order to argue whether the 2022 changes in the regulations are justified in terms of aerodynamic necessities. Both free stream and flow disturbance (wake effects) conditions are evaluated in order to study and quantify the effects that the wake may cause on the latter case. The problem is solved by performing different CFD simulations using the OpenFoam solver. The significance and originality of the research may dictate the guidelines towards an overall improvement of the category and it may set a precedent on how to model racing car aerodynamics. The studied behaviour suggests that modern F1 cars are designed and well optimised to run under free stream flows, but they experience drastic aerodynamic losses (ranging from −23% to 62% in downforce coefficients) when running under wake flows. Although the overall aerodynamic loads are reduced, there is a fuel efficiency improvement as the power that is required to overcome the drag is smaller. The modern performance of Ground Effect by means of vortices management represent a very unique and complex way of modelling modern aerodynamics, but at the same time notably compromises the performance of the cars when an overtaking maneuver is intended. Full article
(This article belongs to the Special Issue The Numerical Simulation of Fluid Flow)
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23 pages, 5969 KiB  
Article
Control and Suppression of Vortex Shedding from a Slightly Rough Circular Cylinder by a Discrete Vortex Method
by Marcos André de Oliveira, Paulo Guimarães de Moraes, Crystianne Lilian de Andrade, Alex Mendonça Bimbato and Luiz Antonio Alcântara Pereira
Energies 2020, 13(17), 4481; https://doi.org/10.3390/en13174481 - 31 Aug 2020
Cited by 16 | Viewed by 4028
Abstract
A discrete vortex method is implemented with a hybrid control technique of vortex shedding to solve the problem of the two-dimensional flow past a slightly rough circular cylinder in the vicinity of a moving wall. In the present approach, the passive control technique [...] Read more.
A discrete vortex method is implemented with a hybrid control technique of vortex shedding to solve the problem of the two-dimensional flow past a slightly rough circular cylinder in the vicinity of a moving wall. In the present approach, the passive control technique is inspired on the fundamental principle of surface roughness, promoting modifications on the cylinder geometry to affect the vortex shedding formation. A relative roughness size of ε*/d* = 0.001 (ε* is the average roughness and d* is the outer cylinder diameter) is chosen for the test cases. On the other hand, the active control technique uses a wall plane, which runs at the same speed as the free stream velocity to contribute with external energy affecting the fluid flow. The gap-to-diameter varies in the range from h*/d* = 0.05 to 0.80 (h* is the gap between the moving wall and the cylinder bottom). A detailed account of the time history of pressure distributions, simultaneously investigated with the time evolution of forces, Strouhal number behavior, and boundary layer separation are reported at upper-subcritical Reynolds number flows of Re = 1.0 × 105. The saturation state of the numerical simulations is demonstrated through the analysis of the Strouhal number behavior obtained from temporal history of the aerodynamic loads. The present work provides an improvement in the prediction of Strouhal number than other studies no using roughness model. The aerodynamic characteristics of the cylinder, as well as the control of intermittence and complete interruption of von Kármán-type vortex shedding have been better clarified. Full article
(This article belongs to the Special Issue The Numerical Simulation of Fluid Flow)
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16 pages, 6927 KiB  
Article
Numeric Simulation of Acoustic-Logging of Cave Formations
by Fanghui Xu and Zhuwen Wang
Energies 2020, 13(15), 3908; https://doi.org/10.3390/en13153908 - 31 Jul 2020
Cited by 5 | Viewed by 2025
Abstract
The finite difference (FD) method of monopole source is used to simulate the response of full-wave acoustic-logging in cave formations. The effect of the cave in the formation of borehole full-waves was studied. The results show that the radius of cave is not [...] Read more.
The finite difference (FD) method of monopole source is used to simulate the response of full-wave acoustic-logging in cave formations. The effect of the cave in the formation of borehole full-waves was studied. The results show that the radius of cave is not only linearly related to the first arrival of the compressional wave (P-wave), but also to the energy of the shear wave (S-wave). The converted S (S–S wave) and P-waves (S–P wave) are formed when the S-wave encounters the cave. If the source distance is small, the S–S and S–P waves are not separated, and the attenuation of the S-wave is not large, due to superposition of the converted waves. The S–P wave has been separated from the S-wave when the source distance is large, so the attenuation of the S-wave increases. The amplitude of the P and S–waves changes most when the distance of the cave to the borehole wall reaches a certain value; this value is related to the excitation frequency. The amplitude of the Stoneley wave (ST wave) varies directly with the radius of cave. If the radius of the cave is large, the energy of ST wave is weak. The scattered wave is determined by the radius and position of the cave. The investigation depth of a monopole source is limited. When the distance of the cave to the borehole wall exceeds the maximum investigation depth, the borehole acoustic wave is little affected by the cave. In actual logging, the development of the cave can be evaluated by using the first arrival of the P-wave and the energy of the S and ST waves. Full article
(This article belongs to the Special Issue The Numerical Simulation of Fluid Flow)
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