Advances in Active and Passive Techniques for Fluid Flow Manipulation

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Fluid Science and Technology".

Deadline for manuscript submissions: 30 June 2024 | Viewed by 2998

Special Issue Editor


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Guest Editor
Fluid Mechanics Department, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain
Interests: active flow control; aerodynamics; compressible flow; fluid mechanics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Flow control technologies are usually employed to modify flow forces acting on bluff bodies. Traditionally, passive flow control devices (where no injection/suction of flow is required) were used, but the tendency nowadays is to interact with the boundary layer using active flow control technologies, mostly because they do not impose any drag penalties in off-design conditions. In this regard, synthetic jets, fluidic oscillators and plasma actuators appear to be particularly efficient since they are capable of generating a pulsating flow, and as a result, the boundary layer can be activated using particularly low levels of energy. In this Special Issue, any scientific research work related to passive and active flow control applications are very welcome, and research considering the design and performance of different actuators will also be accepted. Both experimental work and computational simulations fall into the scope of this Special Issue; moreover, applications considering optimization techniques capable of obtaining optimum parameters will be highly regarded, since they greatly help in minimizing the number of computational simulations while gathering the most appropriate set of active flow control parameters in any given application. Finally, papers considering the application of flow control technology employed to enhance heat transfer on any surface or used to reduce cavitation in water turbines, for example, will also fall into the scope of the present Special Issue.

As a conclusion, it can be stated that any novel research work considering flow control applications to any bluff body is entitled to be published in the present issue.

Dr. Josep Maria Bergadà
Guest Editor

Manuscript Submission Information

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Keywords

  • active and passive flow control applications
  • fluidic oscillators
  • synthetic jets
  • plasma actuators
  • optimization techniques
  • cavitation control
  • heat transfer enhancement

Published Papers (4 papers)

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Research

17 pages, 6847 KiB  
Article
Numerical Modeling of Venous Outflow from the Cranial Cavity in the Supine Body Position
by Marian Simka, Joanna Czaja, Agata Kawalec, Paweł Latacz and Uliana Kovalko
Appl. Sci. 2024, 14(9), 3878; https://doi.org/10.3390/app14093878 - 30 Apr 2024
Viewed by 480
Abstract
The hemodynamic relevance of differently located stenoses of the internal jugular veins remains undetermined. It particularly concerns nozzle-like strictures in the upper parts of these veins and stenotic jugular valves located at the end of these veins. This study was aimed at understanding [...] Read more.
The hemodynamic relevance of differently located stenoses of the internal jugular veins remains undetermined. It particularly concerns nozzle-like strictures in the upper parts of these veins and stenotic jugular valves located at the end of these veins. This study was aimed at understanding flow disturbances caused by such stenoses. The computational fluid dynamics software Flowsquare+ was used. We constructed 3-dimensional models of the venous outflow, comprising two alternative routes: the tube representing the internal jugular vein and an irregular network representing the vertebral veins. At the beginning of the tube representing the internal jugular vein, differently shaped and sized short strictures representing nozzle-like strictures were built in. At the end of this tube, differently shaped membranes representing the jugular valve were built in. With the use of computational fluid dynamics modeling, we studied how these two obstacles influenced the outflow. We found that the most relevant outflow disturbances were evoked by the nozzle-like strictures in the upper part of the internal jugular vein that were small, long, or asymmetrically positioned. Very tight stenotic valves and septum-like malformed valve were equally hemodynamically relevant. These findings suggest that both upper and lower strictures of the internal jugular vein can be of clinical significance. Full article
(This article belongs to the Special Issue Advances in Active and Passive Techniques for Fluid Flow Manipulation)
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27 pages, 6049 KiB  
Article
Beacon, a Lightweight Deep Reinforcement Learning Benchmark Library for Flow Control
by Jonathan Viquerat, Philippe Meliga, Pablo Jeken-Rico and Elie Hachem
Appl. Sci. 2024, 14(9), 3561; https://doi.org/10.3390/app14093561 - 23 Apr 2024
Viewed by 505
Abstract
Recently, the increasing use of deep reinforcement learning for flow control problems has led to a new area of research focused on the coupling and adaptation of the existing algorithms to the control of numerical fluid dynamics environments. Although still in its infancy, [...] Read more.
Recently, the increasing use of deep reinforcement learning for flow control problems has led to a new area of research focused on the coupling and adaptation of the existing algorithms to the control of numerical fluid dynamics environments. Although still in its infancy, the field has seen multiple successes in a short time span, and its fast development pace is certainly partly imparted by the open-source effort that drives the expansion of the community. Yet this emerging domain is still missing a common ground to (i) ensure the reproducibility of the results and (ii) offer a proper ad hoc benchmarking basis. To this end, we propose beacon, an open-source benchmark library composed of seven lightweight one-dimensional and two-dimensional flow control problems with various characteristics, action and observation space characteristics, and CPU requirements. In this contribution, the seven considered problems are described, and reference control solutions are provided. The sources for the following work are publicly available. Full article
(This article belongs to the Special Issue Advances in Active and Passive Techniques for Fluid Flow Manipulation)
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26 pages, 45915 KiB  
Article
Analysis of a Novel Fluidic Oscillator under Several Dimensional Modifications
by Kavoos Karimzadegan, Masoud Mirzaei and Josep M. Bergada
Appl. Sci. 2024, 14(5), 1690; https://doi.org/10.3390/app14051690 - 20 Feb 2024
Viewed by 607
Abstract
To activate the boundary layer in Active Flow Control (AFC) applications, the use of pulsating flow has notable energy advantages over constant blowing/suction jet injections. For a given AFC application, five parameters, jet location and width, inclination angle, frequency of injection, and the [...] Read more.
To activate the boundary layer in Active Flow Control (AFC) applications, the use of pulsating flow has notable energy advantages over constant blowing/suction jet injections. For a given AFC application, five parameters, jet location and width, inclination angle, frequency of injection, and the momentum coefficient, need to be tuned. Presently, two main devices are capable of injecting pulsating flow with a momentum coefficient sufficient to delay the boundary layer separation: these are zero-net-mass-flow Actuators (ZNMFAs) and fluidic oscillators (FOs). In the present study, a novel FO configuration is analyzed for the first time at relatively high Reynolds numbers, and fluid is considered to be incompressible. After obtaining the typical linear correlation between the incoming Reynolds number and the outlet flow oscillating frequency, the effects of dimensional modifications on outlet width and mixing chamber wedge inclination angle are addressed. Modifications of the outlet width were observed to create large variations in FO performance. The origin of self-sustained oscillations is also analyzed in the present manuscript and greatly helps in clarifying the forces acting on the jet inside the mixing chamber. In fact, we can conclude by saying that the current FO configuration is pressure-driven, although the mass flow forces appear to be much more relevant than in previously studied FO configurations. Full article
(This article belongs to the Special Issue Advances in Active and Passive Techniques for Fluid Flow Manipulation)
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26 pages, 53961 KiB  
Article
Numerical and Experimental Characterization of a Coanda-Type Industrial Air Amplifier
by Miguel Chávez-Módena, Alejandro Martinez-Cava, Sergio Marín-Coca and Leo González
Appl. Sci. 2024, 14(4), 1524; https://doi.org/10.3390/app14041524 - 14 Feb 2024
Viewed by 692
Abstract
The performance of an industrial air amplifier is assessed through experimental and numerical characterization, with a focus on examining the influence of various operating conditions (isolated, “blowing,” and “suction” modes) and direct geometric scaling of the device within the specified range of the [...] Read more.
The performance of an industrial air amplifier is assessed through experimental and numerical characterization, with a focus on examining the influence of various operating conditions (isolated, “blowing,” and “suction” modes) and direct geometric scaling of the device within the specified range of the injection gap (δ) and the inlet pressure characteristic values. The findings underscore the presence of a linear trend of the entrained mass flow and a nonlinear decay of the amplification factor, both with notable sensitivity to the gap width. Numerical RANS simulations validate the experimental data, characterize the asymmetric flow downstream from the device, and facilitate the exploration of more complex scenarios. In this regard, scaling the device’s dimensions reveals an optimal aspect ratio between the minimum diameter (Dm) and δ to maximize the entrained mass flow. This research provides valuable insights into the behavior of air amplifiers, offering guidance for their design and application across various industrial contexts. Full article
(This article belongs to the Special Issue Advances in Active and Passive Techniques for Fluid Flow Manipulation)
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