Study of multi-mode forcing effects on coherent structures of flow transition in a compressible jet

The disturbances added to trigger turbulence in the simulation of jet flows are mostly implemented with multiple azimuthal modes. The validity and rationale of using such multi-modes are still not very clear. In this paper, large eddy simulations are performed to study a compressible isothermal jet....

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Autores principales:	Cong Xu, Huanxin Lai
Formato:	article
Lenguaje:	EN
Publicado:	AIP Publishing LLC 2021
Materias:	Physics QC1-999
Acceso en línea:	https://doaj.org/article/f8a6e60846ab45b2935fd14b82f3c73f
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id	oai:doaj.org-article:f8a6e60846ab45b2935fd14b82f3c73f
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spelling	oai:doaj.org-article:f8a6e60846ab45b2935fd14b82f3c73f2021-12-01T18:52:06ZStudy of multi-mode forcing effects on coherent structures of flow transition in a compressible jet2158-322610.1063/5.0067533https://doaj.org/article/f8a6e60846ab45b2935fd14b82f3c73f2021-11-01T00:00:00Zhttp://dx.doi.org/10.1063/5.0067533https://doaj.org/toc/2158-3226The disturbances added to trigger turbulence in the simulation of jet flows are mostly implemented with multiple azimuthal modes. The validity and rationale of using such multi-modes are still not very clear. In this paper, large eddy simulations are performed to study a compressible isothermal jet. Flow forcing methods for promoting transition are considered. Two multi-mode disturbances and a single-mode excitation are shown to trigger rapid flow transition, but the development of mixing layers in downstream varies. The most organized vortical structures produced by the vortex rolling/pairing process are observed when the jet is excited by the single-mode forcing, while the shear layers are closer to turbulence when the two multi-mode disturbances are employed. In order to unveil the mechanism behind such differences, dynamic mode decompositions on the axial velocity are conducted to analyze the spatiotemporal coherent structures. The results show that near the nozzle exit, the multi-mode disturbances have triggered more high frequency coherent structures, while the single-mode forcing has produced both low and high frequencies. The low frequency components are transmitted downstream of the jet, leading to poor prediction of the turbulent flow properties.Cong XuHuanxin LaiAIP Publishing LLCarticlePhysicsQC1-999ENAIP Advances, Vol 11, Iss 11, Pp 115105-115105-16 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999
spellingShingle	Physics QC1-999 Cong Xu Huanxin Lai Study of multi-mode forcing effects on coherent structures of flow transition in a compressible jet
description	The disturbances added to trigger turbulence in the simulation of jet flows are mostly implemented with multiple azimuthal modes. The validity and rationale of using such multi-modes are still not very clear. In this paper, large eddy simulations are performed to study a compressible isothermal jet. Flow forcing methods for promoting transition are considered. Two multi-mode disturbances and a single-mode excitation are shown to trigger rapid flow transition, but the development of mixing layers in downstream varies. The most organized vortical structures produced by the vortex rolling/pairing process are observed when the jet is excited by the single-mode forcing, while the shear layers are closer to turbulence when the two multi-mode disturbances are employed. In order to unveil the mechanism behind such differences, dynamic mode decompositions on the axial velocity are conducted to analyze the spatiotemporal coherent structures. The results show that near the nozzle exit, the multi-mode disturbances have triggered more high frequency coherent structures, while the single-mode forcing has produced both low and high frequencies. The low frequency components are transmitted downstream of the jet, leading to poor prediction of the turbulent flow properties.
format	article
author	Cong Xu Huanxin Lai
author_facet	Cong Xu Huanxin Lai
author_sort	Cong Xu
title	Study of multi-mode forcing effects on coherent structures of flow transition in a compressible jet
title_short	Study of multi-mode forcing effects on coherent structures of flow transition in a compressible jet
title_full	Study of multi-mode forcing effects on coherent structures of flow transition in a compressible jet
title_fullStr	Study of multi-mode forcing effects on coherent structures of flow transition in a compressible jet
title_full_unstemmed	Study of multi-mode forcing effects on coherent structures of flow transition in a compressible jet
title_sort	study of multi-mode forcing effects on coherent structures of flow transition in a compressible jet
publisher	AIP Publishing LLC
publishDate	2021
url	https://doaj.org/article/f8a6e60846ab45b2935fd14b82f3c73f
work_keys_str_mv	AT congxu studyofmultimodeforcingeffectsoncoherentstructuresofflowtransitioninacompressiblejet AT huanxinlai studyofmultimodeforcingeffectsoncoherentstructuresofflowtransitioninacompressiblejet
_version_	1718404669526507520

Study of multi-mode forcing effects on coherent structures of flow transition in a compressible jet

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