Computational Analysis of Active and Passive Flow Control for Backward Facing Step
The internal steady and unsteady flows with a frequency and amplitude are examined through a backward facing step (expansion ratio 2), for low Reynolds numbers (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-01-01
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| Series: | Computation |
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| Online Access: | https://www.mdpi.com/2079-3197/10/1/12 |
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| author | Iosif Moulinos Christos Manopoulos Sokrates Tsangaris |
| author_facet | Iosif Moulinos Christos Manopoulos Sokrates Tsangaris |
| author_sort | Iosif Moulinos |
| collection | DOAJ |
| description | The internal steady and unsteady flows with a frequency and amplitude are examined through a backward facing step (expansion ratio 2), for low Reynolds numbers (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>400</mn></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>800</mn></mrow></semantics></math></inline-formula>), using the immersed boundary method. A lower part of the backward facing step is oscillating with the same frequency as the unsteady flow. The effect of the frequency, the amplitude, and the length of this oscillation is investigated. By suitable active control regulation, the recirculation lengths are reduced, and, for a percentage of the time period, no upper wall, negative velocity, region occurs. Moreover, substituting the prescriptively moving surface by a pressure responsive homogeneous membrane, the fluid–structure interaction is examined. We show that, by selecting proper values for the membrane parameters, such as membrane tension and applied external pressure, the upper wall flow separation bubble vanishes, while the lower one diminishes significantly in both the steady and the unsteady cases. Furthermore, for the time varying case, the length fluctuation of the lower wall reversed flow region is fairly contracted. The findings of the study have applications at the control of confined and external flows where separation occurs. |
| first_indexed | 2024-03-10T01:41:23Z |
| format | Article |
| id | doaj.art-722c0e1627a540cfb7522fe0eb1bbd15 |
| institution | Directory Open Access Journal |
| issn | 2079-3197 |
| language | English |
| last_indexed | 2024-03-10T01:41:23Z |
| publishDate | 2022-01-01 |
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| record_format | Article |
| series | Computation |
| spelling | doaj.art-722c0e1627a540cfb7522fe0eb1bbd152023-11-23T13:23:22ZengMDPI AGComputation2079-31972022-01-011011210.3390/computation10010012Computational Analysis of Active and Passive Flow Control for Backward Facing StepIosif Moulinos0Christos Manopoulos1Sokrates Tsangaris2Laboratory of Biofluid Mechanics & Biomedical Engineering, School of Mechanical Engineering, National Technical University of Athens, Zografos, 15780 Athens, GreeceLaboratory of Biofluid Mechanics & Biomedical Engineering, School of Mechanical Engineering, National Technical University of Athens, Zografos, 15780 Athens, GreeceLaboratory of Biofluid Mechanics & Biomedical Engineering, School of Mechanical Engineering, National Technical University of Athens, Zografos, 15780 Athens, GreeceThe internal steady and unsteady flows with a frequency and amplitude are examined through a backward facing step (expansion ratio 2), for low Reynolds numbers (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>400</mn></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>800</mn></mrow></semantics></math></inline-formula>), using the immersed boundary method. A lower part of the backward facing step is oscillating with the same frequency as the unsteady flow. The effect of the frequency, the amplitude, and the length of this oscillation is investigated. By suitable active control regulation, the recirculation lengths are reduced, and, for a percentage of the time period, no upper wall, negative velocity, region occurs. Moreover, substituting the prescriptively moving surface by a pressure responsive homogeneous membrane, the fluid–structure interaction is examined. We show that, by selecting proper values for the membrane parameters, such as membrane tension and applied external pressure, the upper wall flow separation bubble vanishes, while the lower one diminishes significantly in both the steady and the unsteady cases. Furthermore, for the time varying case, the length fluctuation of the lower wall reversed flow region is fairly contracted. The findings of the study have applications at the control of confined and external flows where separation occurs.https://www.mdpi.com/2079-3197/10/1/12active and passive flow controlcurvilinear immersed boundary methodbackward facing stepfluid–structure interactionelastic membraneoscillating surface |
| spellingShingle | Iosif Moulinos Christos Manopoulos Sokrates Tsangaris Computational Analysis of Active and Passive Flow Control for Backward Facing Step Computation active and passive flow control curvilinear immersed boundary method backward facing step fluid–structure interaction elastic membrane oscillating surface |
| title | Computational Analysis of Active and Passive Flow Control for Backward Facing Step |
| title_full | Computational Analysis of Active and Passive Flow Control for Backward Facing Step |
| title_fullStr | Computational Analysis of Active and Passive Flow Control for Backward Facing Step |
| title_full_unstemmed | Computational Analysis of Active and Passive Flow Control for Backward Facing Step |
| title_short | Computational Analysis of Active and Passive Flow Control for Backward Facing Step |
| title_sort | computational analysis of active and passive flow control for backward facing step |
| topic | active and passive flow control curvilinear immersed boundary method backward facing step fluid–structure interaction elastic membrane oscillating surface |
| url | https://www.mdpi.com/2079-3197/10/1/12 |
| work_keys_str_mv | AT iosifmoulinos computationalanalysisofactiveandpassiveflowcontrolforbackwardfacingstep AT christosmanopoulos computationalanalysisofactiveandpassiveflowcontrolforbackwardfacingstep AT sokratestsangaris computationalanalysisofactiveandpassiveflowcontrolforbackwardfacingstep |