Sound radiation by a vortex pair moving near a rectangular cylinder.
The sound generated by a vortex pair moving close to a rectangular cylinder is studied by high-resolution simulations of the two-dimensional unsteady compressible Navier-Stokes equations at Mach numbers ranging from 0.05 to 0.3. In this study, the Mach number Ma is defined by Ma=Vt /c0, where Vt is...
| Main Authors: | , , |
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| Format: | Article |
| Language: | Japanese |
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The Japan Society of Mechanical Engineers
2022-12-01
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| Series: | Nihon Kikai Gakkai ronbunshu |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/transjsme/89/917/89_22-00223/_pdf/-char/en |
| _version_ | 1797942152298233856 |
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| author | Tsuyoshi KANUMA Yohei INOUE Hiroshi MAEKAWA |
| author_facet | Tsuyoshi KANUMA Yohei INOUE Hiroshi MAEKAWA |
| author_sort | Tsuyoshi KANUMA |
| collection | DOAJ |
| description | The sound generated by a vortex pair moving close to a rectangular cylinder is studied by high-resolution simulations of the two-dimensional unsteady compressible Navier-Stokes equations at Mach numbers ranging from 0.05 to 0.3. In this study, the Mach number Ma is defined by Ma=Vt /c0, where Vt is the translation velocity of the co-moving vortex pair and c0 denotes the speed of sound. The directly computed far-field sound is compared to the prediction of the acoustic analogy proposed by Lighthill (1952) and Curle (1955). The prediction is in excellent agreement with the simulation, where the two-dimensional form of Curle’s modified solution is adopted for an accurate calculation of the sound waves with a phase difference between various vortices around the cylinder. It could be confirmed that the scaling law in two dimensions holds in this simulation. In this study, the sound generation due to the dipole and quadrupole fields is investigated by calculating the two terms in Curle’s analogy. Examining the surface distribution of dipoles on the cylinder indicates that the force exerted on the fluid by the solid boundaries of the side/upper wall of the rectangular cylinder generates the sound when the co-translating vortices approach /pass the rectangular cylinder, which is the sound due to dipoles corresponding to the directivity of the sound in the polar diagrams. The area distribution of quadrupoles which is the second time derivative of the area integral of Lighthill’s stress tensor indicates that the sound is emitted from a vortex generated at the corner of the rectangular cylinder when the vortex pair approaches the cylinder and where the interaction between many vortices around the cylinder and the co-translating vortices generates the sound when the co-translating vortices pass the cylinder. |
| first_indexed | 2024-04-10T20:03:56Z |
| format | Article |
| id | doaj.art-afba33c9afd94baeaacfa659b33e0aff |
| institution | Directory Open Access Journal |
| issn | 2187-9761 |
| language | Japanese |
| last_indexed | 2024-04-10T20:03:56Z |
| publishDate | 2022-12-01 |
| publisher | The Japan Society of Mechanical Engineers |
| record_format | Article |
| series | Nihon Kikai Gakkai ronbunshu |
| spelling | doaj.art-afba33c9afd94baeaacfa659b33e0aff2023-01-27T02:49:34ZjpnThe Japan Society of Mechanical EngineersNihon Kikai Gakkai ronbunshu2187-97612022-12-018991722-0022322-0022310.1299/transjsme.22-00223transjsmeSound radiation by a vortex pair moving near a rectangular cylinder.Tsuyoshi KANUMA0Yohei INOUE1Hiroshi MAEKAWA2Highly-Marelli JapanDepartment of Mechanical Engineering and Intelligent Systems The University of Electro-Communications (UEC)Department of Mechanical Engineering and Intelligent Systems The University of Electro-Communications (UEC)The sound generated by a vortex pair moving close to a rectangular cylinder is studied by high-resolution simulations of the two-dimensional unsteady compressible Navier-Stokes equations at Mach numbers ranging from 0.05 to 0.3. In this study, the Mach number Ma is defined by Ma=Vt /c0, where Vt is the translation velocity of the co-moving vortex pair and c0 denotes the speed of sound. The directly computed far-field sound is compared to the prediction of the acoustic analogy proposed by Lighthill (1952) and Curle (1955). The prediction is in excellent agreement with the simulation, where the two-dimensional form of Curle’s modified solution is adopted for an accurate calculation of the sound waves with a phase difference between various vortices around the cylinder. It could be confirmed that the scaling law in two dimensions holds in this simulation. In this study, the sound generation due to the dipole and quadrupole fields is investigated by calculating the two terms in Curle’s analogy. Examining the surface distribution of dipoles on the cylinder indicates that the force exerted on the fluid by the solid boundaries of the side/upper wall of the rectangular cylinder generates the sound when the co-translating vortices approach /pass the rectangular cylinder, which is the sound due to dipoles corresponding to the directivity of the sound in the polar diagrams. The area distribution of quadrupoles which is the second time derivative of the area integral of Lighthill’s stress tensor indicates that the sound is emitted from a vortex generated at the corner of the rectangular cylinder when the vortex pair approaches the cylinder and where the interaction between many vortices around the cylinder and the co-translating vortices generates the sound when the co-translating vortices pass the cylinder.https://www.jstage.jst.go.jp/article/transjsme/89/917/89_22-00223/_pdf/-char/ensoundcomputational fluid dynamicscomputational aeroacousticsvortex soundacoustic analogy |
| spellingShingle | Tsuyoshi KANUMA Yohei INOUE Hiroshi MAEKAWA Sound radiation by a vortex pair moving near a rectangular cylinder. Nihon Kikai Gakkai ronbunshu sound computational fluid dynamics computational aeroacoustics vortex sound acoustic analogy |
| title | Sound radiation by a vortex pair moving near a rectangular cylinder. |
| title_full | Sound radiation by a vortex pair moving near a rectangular cylinder. |
| title_fullStr | Sound radiation by a vortex pair moving near a rectangular cylinder. |
| title_full_unstemmed | Sound radiation by a vortex pair moving near a rectangular cylinder. |
| title_short | Sound radiation by a vortex pair moving near a rectangular cylinder. |
| title_sort | sound radiation by a vortex pair moving near a rectangular cylinder |
| topic | sound computational fluid dynamics computational aeroacoustics vortex sound acoustic analogy |
| url | https://www.jstage.jst.go.jp/article/transjsme/89/917/89_22-00223/_pdf/-char/en |
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