Volume 13, Issue 1
Numerical Investigation of Sound Generation due to Laminar Flow Past Elliptic Cylinders

Numer. Math. Theor. Meth. Appl., 13 (2020), pp. 27-62.

Published online: 2019-12

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• Abstract

Numerical investigation of sound generation due to unsteady laminar flow past elliptic cylinders has been carried out using direct numerical simulation $(DNS)$ approach at a free-stream Mach number of $0.2$. Effects of aspect ratio $(0.6\le AR\le 1.0)$ and Reynolds number $(100\le Re \le 160)$ on the characteristics of radiated sound fields are analyzed. Two-dimensional compressible fluid flow equations are solved on a refined grid using high resolution dispersion relation preserving $(DRP)$ schemes. Using present $DNS$ data, equivalent noise sources as given by various acoustic analogies are evaluated. Amplitudes and frequencies associated with these noise sources are further related to characteristics of disturbance pressure fields. Disturbance pressure fields are intensified with increase in Reynolds number and aspect ratio. Thus, radiated sound power increases with increase in Reynolds number and aspect ratio. Among various cases studied here, minimum and maximum values of radiated sound power are found at $Re=120$ \& $AR=0.6$ and $Re=160$ \& $AR=1.0$, respectively. Directivity patterns show that the generated sound fields are dominated by the lift dipole for all cases. Next, proper orthogonal decomposition $(POD)$ technique has been implemented for decomposing disturbance pressure fields. The $POD$ modes associated with the lift and the drag dipoles have been identified. $POD$ analyses also clearly display that the radiated sound fields are dominated by the lift dipole only. Further, acoustic and hydrodynamic modes obtained using Doak's decomposition method have confirmed the patterns of radiated sound field intensities.

• Keywords

Computational aeroacoustics, acoustic analogies, aeolian tones, proper orthogonal decomposition, Doak's decomposition.

76Q05, 76M20, 76G25

bm18@iitbbs.ac.in (Bikash Mahato)

ng13@iitbbs.ac.in (Naveen Ganta)

jp10@iitbbs.ac.in (Yogesh G. Bhumkar)

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• RIS
• TXT
@Article{NMTMA-13-27, author = {Mahato , Bikash and Ganta , Naveen and G. Bhumkar , Yogesh }, title = {Numerical Investigation of Sound Generation due to Laminar Flow Past Elliptic Cylinders}, journal = {Numerical Mathematics: Theory, Methods and Applications}, year = {2019}, volume = {13}, number = {1}, pages = {27--62}, abstract = {

Numerical investigation of sound generation due to unsteady laminar flow past elliptic cylinders has been carried out using direct numerical simulation $(DNS)$ approach at a free-stream Mach number of $0.2$. Effects of aspect ratio $(0.6\le AR\le 1.0)$ and Reynolds number $(100\le Re \le 160)$ on the characteristics of radiated sound fields are analyzed. Two-dimensional compressible fluid flow equations are solved on a refined grid using high resolution dispersion relation preserving $(DRP)$ schemes. Using present $DNS$ data, equivalent noise sources as given by various acoustic analogies are evaluated. Amplitudes and frequencies associated with these noise sources are further related to characteristics of disturbance pressure fields. Disturbance pressure fields are intensified with increase in Reynolds number and aspect ratio. Thus, radiated sound power increases with increase in Reynolds number and aspect ratio. Among various cases studied here, minimum and maximum values of radiated sound power are found at $Re=120$ \& $AR=0.6$ and $Re=160$ \& $AR=1.0$, respectively. Directivity patterns show that the generated sound fields are dominated by the lift dipole for all cases. Next, proper orthogonal decomposition $(POD)$ technique has been implemented for decomposing disturbance pressure fields. The $POD$ modes associated with the lift and the drag dipoles have been identified. $POD$ analyses also clearly display that the radiated sound fields are dominated by the lift dipole only. Further, acoustic and hydrodynamic modes obtained using Doak's decomposition method have confirmed the patterns of radiated sound field intensities.

}, issn = {2079-7338}, doi = {https://doi.org/10.4208/nmtma.OA-2019-0042}, url = {http://global-sci.org/intro/article_detail/nmtma/13429.html} }
TY - JOUR T1 - Numerical Investigation of Sound Generation due to Laminar Flow Past Elliptic Cylinders AU - Mahato , Bikash AU - Ganta , Naveen AU - G. Bhumkar , Yogesh JO - Numerical Mathematics: Theory, Methods and Applications VL - 1 SP - 27 EP - 62 PY - 2019 DA - 2019/12 SN - 13 DO - http://dor.org/10.4208/nmtma.OA-2019-0042 UR - https://global-sci.org/intro/article_detail/nmtma/13429.html KW - Computational aeroacoustics, acoustic analogies, aeolian tones, proper orthogonal decomposition, Doak's decomposition. AB -

Numerical investigation of sound generation due to unsteady laminar flow past elliptic cylinders has been carried out using direct numerical simulation $(DNS)$ approach at a free-stream Mach number of $0.2$. Effects of aspect ratio $(0.6\le AR\le 1.0)$ and Reynolds number $(100\le Re \le 160)$ on the characteristics of radiated sound fields are analyzed. Two-dimensional compressible fluid flow equations are solved on a refined grid using high resolution dispersion relation preserving $(DRP)$ schemes. Using present $DNS$ data, equivalent noise sources as given by various acoustic analogies are evaluated. Amplitudes and frequencies associated with these noise sources are further related to characteristics of disturbance pressure fields. Disturbance pressure fields are intensified with increase in Reynolds number and aspect ratio. Thus, radiated sound power increases with increase in Reynolds number and aspect ratio. Among various cases studied here, minimum and maximum values of radiated sound power are found at $Re=120$ \& $AR=0.6$ and $Re=160$ \& $AR=1.0$, respectively. Directivity patterns show that the generated sound fields are dominated by the lift dipole for all cases. Next, proper orthogonal decomposition $(POD)$ technique has been implemented for decomposing disturbance pressure fields. The $POD$ modes associated with the lift and the drag dipoles have been identified. $POD$ analyses also clearly display that the radiated sound fields are dominated by the lift dipole only. Further, acoustic and hydrodynamic modes obtained using Doak's decomposition method have confirmed the patterns of radiated sound field intensities.

Bikash Mahato, Naveen Ganta & Yogesh G. Bhumkar. (2019). Numerical Investigation of Sound Generation due to Laminar Flow Past Elliptic Cylinders. Numerical Mathematics: Theory, Methods and Applications. 13 (1). 27-62. doi:10.4208/nmtma.OA-2019-0042
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