On g-jitter effects on three-dimensional laminar thermal convection in low gravity

We numerically study the forced-oscillation-frequency responses on the three-dimensional thermal convection in a cubic cavity heated from one wall and chilled from its opposite wall in the non-gravitational field at vibrational Rayleigh number (the Rayleigh number based on the cavity's acce...

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Autores principales:	Katsuya HIRATA, Keisuke TATSUMOTO, Masaki NOBUHARA, Hirochika TANIGAWA
Formato:	article
Lenguaje:	EN
Publicado:	The Japan Society of Mechanical Engineers 2015
Materias:	rayleigh-bénard convection natural convection thermal convection forced oscillation forced vibration cubic cavity laminar flow Mechanical engineering and machinery TJ1-1570
Acceso en línea:	https://doaj.org/article/83accb746d35419bbacde6587e5d062e
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spelling	oai:doaj.org-article:83accb746d35419bbacde6587e5d062e2021-11-26T06:30:10ZOn g-jitter effects on three-dimensional laminar thermal convection in low gravity2187-974510.1299/mej.15-00268https://doaj.org/article/83accb746d35419bbacde6587e5d062e2015-08-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/mej/2/5/2_15-00268/_pdf/-char/enhttps://doaj.org/toc/2187-9745We numerically study the forced-oscillation-frequency responses on the three-dimensional thermal convection in a cubic cavity heated from one wall and chilled from its opposite wall in the non-gravitational field at vibrational Rayleigh number (the Rayleigh number based on the cavity's acceleration amplitude instead of the gravitational acceleration) Raη = 5.0×103 - 1.1×105, Plandtl number Pr = 7.1 (water) and non-dimensional forced-oscillation frequency ω = 1.0×100 - 1.0×103. The direction of the forced sinusoidal oscillation is parallel to the temperature gradient inside the cubic cavity. We especially focus upon the influences of both Raη and ω. As a result, five kinds of structures S2 (with a single roll), S4 (with a toroidal roll), S5 (with four roll), S6 (with four roll) and Sα (with six roll) appear in the tested ranges of Raη and ω. The Sα consists of a pair of trident currents, namely, three ascending streams and three matching descending streams in the cubic cavity. And, such flow structures are revealed in detail. Whenever it is not conductive but convective for ω < 5.0×10 2, convective motion always starts with the S4 from the rest at each forcing cycle. We find out the optimum frequency ω\|K\|max where the amplitude of a spatially-averaged kinetic energy K, which is defined by the difference between the maximum K and the minimum K over one forcing cycle, attains the maximum at each Raη. At ω = ω\|K\|max max, the flow structure is characterised by the S4. So, this fact suggests that the optimum frequency can be related with the S4. In addition, we show the occurrence condition for convection as a function of Raη and ω, and the boundary for the quasi-steady approximation which is permissible at ω ≲ 100 from a quantitative viewpoint.Katsuya HIRATAKeisuke TATSUMOTOMasaki NOBUHARAHirochika TANIGAWAThe Japan Society of Mechanical Engineersarticlerayleigh-bénard convectionnatural convectionthermal convectionforced oscillationforced vibrationcubic cavitylaminar flowMechanical engineering and machineryTJ1-1570ENMechanical Engineering Journal, Vol 2, Iss 5, Pp 15-00268-15-00268 (2015)
institution	DOAJ
collection	DOAJ
language	EN
topic	rayleigh-bénard convection natural convection thermal convection forced oscillation forced vibration cubic cavity laminar flow Mechanical engineering and machinery TJ1-1570
spellingShingle	rayleigh-bénard convection natural convection thermal convection forced oscillation forced vibration cubic cavity laminar flow Mechanical engineering and machinery TJ1-1570 Katsuya HIRATA Keisuke TATSUMOTO Masaki NOBUHARA Hirochika TANIGAWA On g-jitter effects on three-dimensional laminar thermal convection in low gravity
description	We numerically study the forced-oscillation-frequency responses on the three-dimensional thermal convection in a cubic cavity heated from one wall and chilled from its opposite wall in the non-gravitational field at vibrational Rayleigh number (the Rayleigh number based on the cavity's acceleration amplitude instead of the gravitational acceleration) Raη = 5.0×103 - 1.1×105, Plandtl number Pr = 7.1 (water) and non-dimensional forced-oscillation frequency ω = 1.0×100 - 1.0×103. The direction of the forced sinusoidal oscillation is parallel to the temperature gradient inside the cubic cavity. We especially focus upon the influences of both Raη and ω. As a result, five kinds of structures S2 (with a single roll), S4 (with a toroidal roll), S5 (with four roll), S6 (with four roll) and Sα (with six roll) appear in the tested ranges of Raη and ω. The Sα consists of a pair of trident currents, namely, three ascending streams and three matching descending streams in the cubic cavity. And, such flow structures are revealed in detail. Whenever it is not conductive but convective for ω < 5.0×10 2, convective motion always starts with the S4 from the rest at each forcing cycle. We find out the optimum frequency ω\|K\|max where the amplitude of a spatially-averaged kinetic energy K, which is defined by the difference between the maximum K and the minimum K over one forcing cycle, attains the maximum at each Raη. At ω = ω\|K\|max max, the flow structure is characterised by the S4. So, this fact suggests that the optimum frequency can be related with the S4. In addition, we show the occurrence condition for convection as a function of Raη and ω, and the boundary for the quasi-steady approximation which is permissible at ω ≲ 100 from a quantitative viewpoint.
format	article
author	Katsuya HIRATA Keisuke TATSUMOTO Masaki NOBUHARA Hirochika TANIGAWA
author_facet	Katsuya HIRATA Keisuke TATSUMOTO Masaki NOBUHARA Hirochika TANIGAWA
author_sort	Katsuya HIRATA
title	On g-jitter effects on three-dimensional laminar thermal convection in low gravity
title_short	On g-jitter effects on three-dimensional laminar thermal convection in low gravity
title_full	On g-jitter effects on three-dimensional laminar thermal convection in low gravity
title_fullStr	On g-jitter effects on three-dimensional laminar thermal convection in low gravity
title_full_unstemmed	On g-jitter effects on three-dimensional laminar thermal convection in low gravity
title_sort	on g-jitter effects on three-dimensional laminar thermal convection in low gravity
publisher	The Japan Society of Mechanical Engineers
publishDate	2015
url	https://doaj.org/article/83accb746d35419bbacde6587e5d062e
work_keys_str_mv	AT katsuyahirata ongjittereffectsonthreedimensionallaminarthermalconvectioninlowgravity AT keisuketatsumoto ongjittereffectsonthreedimensionallaminarthermalconvectioninlowgravity AT masakinobuhara ongjittereffectsonthreedimensionallaminarthermalconvectioninlowgravity AT hirochikatanigawa ongjittereffectsonthreedimensionallaminarthermalconvectioninlowgravity
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On g-jitter effects on three-dimensional laminar thermal convection in low gravity

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