1
|
Ueta R, Gotoda H, Okamoto H, Kawano K, Shoji T, Yoshida S. Interaction of acoustic pressure and heat release rate fluctuations in a model rocket engine combustor. Phys Rev E 2024; 110:014202. [PMID: 39161027 DOI: 10.1103/physreve.110.014202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 05/15/2024] [Indexed: 08/21/2024]
Abstract
We experimentally clarify the interaction of acoustic pressure and heat release rate fluctuations during a transition to high-frequency combustion instability in a model rocket engine combustor. The dynamical state of acoustic pressure fluctuations undergoes a transition from high-dimensional chaotic oscillations to strongly correlated limit cycle oscillations. The coherent structure in the heat release rate field emerges with the initiation of weakly correlated limit cycle oscillations. The effect of the heat release rate on acoustic pressure fluctuations predominates during high-dimensional chaotic oscillations. In contrast, the effect of acoustic pressure on the heat release rate fluctuations markedly increases during the correlated limit cycle oscillations. These are reasonably shown by an ordinal pattern-based analysis involving the concepts of information theory, synchronization, and complex networks.
Collapse
|
2
|
Tokami T, Toyoda M, Miyano T, Tokuda IT, Gotoda H. Effect of gravity on synchronization of two coupled buoyancy-induced turbulent flames. Phys Rev E 2021; 104:024218. [PMID: 34525657 DOI: 10.1103/physreve.104.024218] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 06/15/2021] [Indexed: 11/07/2022]
Abstract
We study the effect of gravity on the synchronization of two coupled buoyancy-induced turbulent flames by recurrence-based analysis and machine learning. A significant change from nearly complete synchronization in the near field to partial synchronization appears in the far field under low gravity. The synchronized state is gradually lost with increasing gravity level. These results are clearly identified from cross recurrence plots and symbolic recurrence plots and by reservoir computing.
Collapse
Affiliation(s)
- Takumi Tokami
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika, Tokyo 125-8585, Japan
| | - Masaharu Toyoda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika, Tokyo 125-8585, Japan
| | - Takaya Miyano
- Department of Mechanical Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| | - Isao T Tokuda
- Department of Mechanical Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| | - Hiroshi Gotoda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika, Tokyo 125-8585, Japan
| |
Collapse
|
3
|
Fernandes LHS, de Araujo FHA, Tabak BM. Insights from the (in)efficiency of Chinese sectoral indices during COVID-19. PHYSICA A 2021; 578:126063. [PMID: 36569041 PMCID: PMC9758612 DOI: 10.1016/j.physa.2021.126063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/26/2021] [Indexed: 05/24/2023]
Abstract
This article evaluates the effects of the crisis caused by the new Coronavirus (COVID-19) on the Chinese sectoral indices. Using the complexity-entropy plane methodology, we find that the COVID-19 crisis caused increased inefficiency in most of China's equity sectors. We also find heterogeneous effects depending on the economic sector. Our results are useful for a better understanding the effect of global shocks on the stock markets and how their effects are distributed across economic sectors.
Collapse
Affiliation(s)
- Leonardo H S Fernandes
- Department of Economics and Informatics, Federal Rural University of Pernambuco, Av. Gregório Ferraz Nogueira, S/N - José Tomé de Souza Ramos, 569090-535, PE, Serra Talhada, Brazil
| | - Fernando H A de Araujo
- Department of Statistics and Informatics, Federal Rural University of Pernambuco, Rua Dom Manuel de Medeiros, S/N Dois Irmãos - CEP: 52171-900, PE, Recife, Brazil
| | - Benjamin M Tabak
- School of Public Policy and Government, Getulio Vargas Foundation (EPPG/FGV), Brasilia, DF, Brazil
| |
Collapse
|
4
|
Nomi Y, Gotoda H, Kandani S, Almarcha C. Complex network analysis of the gravity effect on premixed flames propagating in a Hele-Shaw cell. Phys Rev E 2021; 103:022218. [PMID: 33736026 DOI: 10.1103/physreve.103.022218] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 01/06/2021] [Indexed: 06/12/2023]
Abstract
We study the effect of gravity on spatiotemporal flame front dynamics in a Hele-Shaw cell from the viewpoint of complex networks. The randomness in flame front dynamics significantly increases with the gravitational level when the normalized Rayleigh number R_{a} is negative. This is clearly identified by two network entropies: the flame front network entropy and the transition network entropy. The irregular formation of large-scale wrinkles driven by the Rayleigh-Taylor instability plays an important role in the formation of high-dimensional deterministic chaos at R_{a}<0, resulting in the increase in the randomness of flame front dynamics.
Collapse
Affiliation(s)
- Yuji Nomi
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika, Tokyo 125-8585, Japan
| | | | | | - Christophe Almarcha
- Aix-Marseille University, CNRS, Centrale Marseille, IRPHE, F-13451 Marseille Cedex 20, France
| |
Collapse
|
5
|
Tokami T, Hachijo T, Miyano T, Gotoda H. Spatiotemporal dynamics of a buoyancy-driven turbulent fire. Phys Rev E 2020; 101:042214. [PMID: 32422785 DOI: 10.1103/physreve.101.042214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 03/14/2020] [Indexed: 06/11/2023]
Abstract
We numerically study the spatiotemporal dynamics and predictability of a buoyancy-driven turbulent fire. A significant transition from order to disorder structures can be observed from the mean degree in the spatial horizontal visibility graph. The gravitational term (baroclinic torque term) in the vorticity equation has a significant impact on the formation of the order (disorder) structure in the near field (far field). The entropy flow transport from temperature to flow velocity fluctuations is predominant near the interface between hot combustion products and ambient air. The transfer entropy is an important measure for determining the predictability of flow velocity fluctuations in the near field obtained by reservoir computing.
Collapse
Affiliation(s)
- Takumi Tokami
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Takayoshi Hachijo
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Takaya Miyano
- Department of Mechanical Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| | - Hiroshi Gotoda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| |
Collapse
|
6
|
Kobayashi W, Gotoda H, Kandani S, Ohmichi Y, Matsuyama S. Spatiotemporal dynamics of turbulent coaxial jet analyzed by symbolic information-theory quantifiers and complex-network approach. CHAOS (WOODBURY, N.Y.) 2019; 29:123110. [PMID: 31893639 DOI: 10.1063/1.5126490] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/19/2019] [Indexed: 06/10/2023]
Abstract
We numerically study the spatiotemporal dynamics of a turbulent coaxial jet in a model rocket engine combustor from the viewpoints of symbolic information-theory quantifiers and complex networks. The dynamic behavior of flow velocity undergoes a significant transition from a stochastic to chaotic state as the turbulent jet moves downstream. The small-world nature exists in the near field forming a stochastic state, whereas it disappears by the formation of a chaotic state in the far field. The dynamic behavior of hydrogen and oxygen concentrations in the far field also represents deterministic chaos. The simultaneous dynamic behavior with chaotic mixing forms the phase-synchronization state.
Collapse
Affiliation(s)
- Wataru Kobayashi
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Hiroshi Gotoda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Shuya Kandani
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Yuya Ohmichi
- Japan Aerospace Exploration Agency, 7-44-1 Jindaiji-Higashimachi, Chofu-shi, Tokyo 182-8522, Japan
| | - Shingo Matsuyama
- Japan Aerospace Exploration Agency, 7-44-1 Jindaiji-Higashimachi, Chofu-shi, Tokyo 182-8522, Japan
| |
Collapse
|
7
|
Hachijo T, Masuda S, Kurosaka T, Gotoda H. Early detection of thermoacoustic combustion oscillations using a methodology combining statistical complexity and machine learning. CHAOS (WOODBURY, N.Y.) 2019; 29:103123. [PMID: 31675849 DOI: 10.1063/1.5120815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Accepted: 08/28/2019] [Indexed: 06/10/2023]
Abstract
We conduct an experimental study on early detection of thermoacoustic combustion oscillations using a method combining statistical complexity and machine learning, including the characterization of intermittent combustion oscillations. Abrupt switching from aperiodic small-amplitude oscillations to periodic large-amplitude oscillations and vice versa appears in pressure fluctuations. The dynamic behavior of aperiodic small-amplitude pressure fluctuations represents chaos. The complexity-entropy causality plane effectively captures the subtle changes in the combustion state during a transition to well-developed combustion oscillations. The feature space of the complexity-entropy causality plane, which is obtained by a support vector machine, has potential use for detecting a precursor of combustion oscillations.
Collapse
Affiliation(s)
- Takayoshi Hachijo
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Shinga Masuda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Takuya Kurosaka
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Hiroshi Gotoda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| |
Collapse
|
8
|
Huffaker R, Fearne A. Reconstructing systematic persistent impacts of promotional marketing with empirical nonlinear dynamics. PLoS One 2019; 14:e0221167. [PMID: 31532779 PMCID: PMC6750578 DOI: 10.1371/journal.pone.0221167] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 07/31/2019] [Indexed: 11/30/2022] Open
Abstract
An empirical question of long-standing interest is how price promotions affect a brand’s sale shares in the fast-moving consumer-goods market. We investigated this question with concurrent promotions and sales records of specialty beer brands pooled over Tesco stores in the UK. Most brands were continuously promoted, rendering infeasible a conventional approach of establishing impact against an off-promotion sales baseline, and arguing in favor of a dynamics approach. Moreover, promotion/sales records were volatile without easily-discernable regularity. Past work conventionally attributed volatility to the impact of exogenous random shocks on stable markets, and reasoned that promotions have only an ephemeral impact on sales shares in stationary mean-reverting stochastic markets, or a persistent freely-wandering impact in nonstationary markets. We applied new empirical methods from the applied sciences to uncover an overlooked alternative: ‘systematic persistence’ in which promotional impacts evolve systematically in an endogenously-unstable market governed by deterministic-nonlinear dynamics. We reconstructed real-world market dynamics from the Tesco dataset, and detected deterministic-nonlinear market dynamics. We used reconstructed market dynamics to identify a complex network of systematic interactions between promotions and sales shares among competing brands, and quantified/characterized the dynamics of these interactions. For the majority of weeks in the study, we found that: (1) A brand’s promotions drove down own sales shares (a possibility recognized in the literature), but ‘cannibalized’ sales shares of competing brands (perhaps explaining why brands were promoted despite a negative marginal impact on own sales shares); and (2) Competitive interactions between brands owned by the same multinational brewery differed from those with outside brands. In particular, brands owned by the same brewery enjoyed a ‘mutually-beneficial’ relationship in which an incremental increase in the sales share of one marginally increased the sales share of the other. Alternatively, the sales shares of brands owned by different breweries preyed on each other’s market shares.
Collapse
Affiliation(s)
- Ray Huffaker
- Department of Agricultural and Biological Engineering, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
| | - Andrew Fearne
- Norwich Business School, University of East Anglia, Norwich, England, United Kingdom
| |
Collapse
|
9
|
Murayama S, Gotoda H. Attenuation behavior of thermoacoustic combustion instability analyzed by a complex-network- and synchronization-based approach. Phys Rev E 2019; 99:052222. [PMID: 31212465 DOI: 10.1103/physreve.99.052222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Indexed: 06/09/2023]
Abstract
We conduct an experimental study of the attenuation behavior of thermoacoustic combustion instability from the viewpoints of complex networks and synchronization. The spatiotemporally phase-synchronized state between the vertexes in weighted networks near an injector rim is notably degenerated as thermoacoustic combustion instability is suppressed by a steady air jet issued from the injector rim. The synchronization index clearly captures the attenuation of the mutual coupling between pressure and heat release rate fluctuations. The decrease in the periodicity of noisy-periodic oscillations in a flow velocity field significantly affects the mutual coupling, resulting in the suppression of thermoacoustic combustion instability.
Collapse
Affiliation(s)
- Shogo Murayama
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Hiroshi Gotoda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| |
Collapse
|
10
|
Hashimoto T, Shibuya H, Gotoda H, Ohmichi Y, Matsuyama S. Spatiotemporal dynamics and early detection of thermoacoustic combustion instability in a model rocket combustor. Phys Rev E 2019; 99:032208. [PMID: 30999467 DOI: 10.1103/physreve.99.032208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Indexed: 06/09/2023]
Abstract
We numerically study the spatiotemporal dynamics and early detection of thermoacoustic combustion instability in a model rocket combustor using the theories of complex networks and synchronization. The turbulence network, which consists of nodes and vertexes in weighted networks between vortices, can characterize the complex spatiotemporal structure of a flow field during thermoacoustic combustion instability. The transfer entropy allows us to identify the driving region of thermoacoustic combustion instability. In addition to the order parameter, a phase parameter newly proposed in this study is useful for capturing the precursor of thermoacoustic combustion instability.
Collapse
Affiliation(s)
- Tatsuya Hashimoto
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Hajime Shibuya
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Hiroshi Gotoda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Yuya Ohmichi
- Japan Aerospace Exploration Agency, 7-44-1 Jindaiji-Higashimachi, Chofu-shi, Tokyo 182-8522, Japan
| | - Shingo Matsuyama
- Japan Aerospace Exploration Agency, 7-44-1 Jindaiji-Higashimachi, Chofu-shi, Tokyo 182-8522, Japan
| |
Collapse
|
11
|
Takagi K, Gotoda H, Miyano T, Murayama S, Tokuda IT. Synchronization of two coupled turbulent fires. CHAOS (WOODBURY, N.Y.) 2018; 28:045116. [PMID: 31906626 DOI: 10.1063/1.5009896] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We numerically study the scale-free nature of a buoyancy-induced turbulent fire and synchronization of two coupled turbulent fires. A scale-free structure is detected in weighted networks between vortices, while its lifetime obeys a clear power law, indicating intermittent appearances, disappearances, and reappearances of the scale-free property. A significant decrease in the distance between the two fire sources gives rise to a synchronized state in the near field dominated by the unstable motion of transverse vortex rings. The synchronized state vanishes in the far field forming well-developed turbulent plumes, regardless of the distance between the two fire sources.
Collapse
Affiliation(s)
- Kazushi Takagi
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Hiroshi Gotoda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Takaya Miyano
- Department of Mechanical Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| | - Shogo Murayama
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Isao T Tokuda
- Department of Mechanical Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| |
Collapse
|
12
|
Kasuya H, Gotoda H, Yoshida S, Tachibana S. Dynamic behavior of combustion instability in a cylindrical combustor with an off-center installed coaxial injector. CHAOS (WOODBURY, N.Y.) 2018; 28:033111. [PMID: 29604630 DOI: 10.1063/1.5025480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We have intensively studied the dynamic behavior of combustion instability in a cylindrical combustor with an off-center installed coaxial injector. The most interesting discovery in this study is the appearance of a deterministic chaos in a transition from a dynamically stable state to well-developed high-frequency thermoacoustic combustion oscillations with increasing the volume flow rate of nitrogen with which oxygen is diluted. The presence of deterministic chaos is reasonably identified by considering an extended version of the Sugihara-May algorithm [G. Sugihara and R. May, Nature 344, 734 (1990)] as a local predictor and the multiscale complexity-entropy causality plane based on statistical complexity.
Collapse
Affiliation(s)
- Haruki Kasuya
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Hiroshi Gotoda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Seiji Yoshida
- Japan Aerospace Exploration Agency, 7-44-1 Jindaiji-Higashimachi, Chofu-shi, Tokyo 182-8522, Japan
| | - Shigeru Tachibana
- Japan Aerospace Exploration Agency, 7-44-1 Jindaiji-Higashimachi, Chofu-shi, Tokyo 182-8522, Japan
| |
Collapse
|
13
|
Murayama S, Kinugawa H, Tokuda IT, Gotoda H. Characterization and detection of thermoacoustic combustion oscillations based on statistical complexity and complex-network theory. Phys Rev E 2018; 97:022223. [PMID: 29548163 DOI: 10.1103/physreve.97.022223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Indexed: 06/08/2023]
Abstract
We present an experimental study on the characterization of dynamic behavior of flow velocity field during thermoacoustic combustion oscillations in a turbulent confined combustor from the viewpoints of statistical complexity and complex-network theory, involving detection of a precursor of thermoacoustic combustion oscillations. The multiscale complexity-entropy causality plane clearly shows the possible presence of two dynamics, noisy periodic oscillations and noisy chaos, in the shear layer regions (1) between the outer recirculation region in the dump plate and a recirculation flow in the wake of the centerbody and (2) between the outer recirculation region in the dump plate and a vortex breakdown bubble away from the centerbody. The vertex strength in the turbulence network and the community structure of the vorticity field can identify the vortical interactions during thermoacoustic combustion oscillations. Sequential horizontal visibility graph motifs are useful for capturing a precursor of themoacoustic combustion oscillations.
Collapse
Affiliation(s)
- Shogo Murayama
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika, Tokyo 125-8585, Japan
| | - Hikaru Kinugawa
- Department of Mechanical Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| | - Isao T Tokuda
- Department of Mechanical Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| | - Hiroshi Gotoda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika, Tokyo 125-8585, Japan
| |
Collapse
|
14
|
Takagi K, Gotoda H, Tokuda IT, Miyano T. Nonlinear dynamics of a buoyancy-induced turbulent fire. Phys Rev E 2017; 96:052223. [PMID: 29347727 DOI: 10.1103/physreve.96.052223] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Indexed: 11/07/2022]
Abstract
We conduct a numerical study on the dynamic behavior of a buoyancy-induced turbulent fire from the viewpoints of symbolic dynamics, complex networks, and statistical complexity. Here, we consider two classes of entropies: the permutation entropy and network entropy in ε-recurrence networks, both of which evaluate the degree of randomness in the underlying dynamics. These entropies enable us to capture the significant changes in the dynamic behavior of flow velocity fluctuations. The possible presence of two important dynamics, low-dimensional deterministic chaos in the near field dominated by the motion of large-scale vortices and high-dimensional chaos in the far field forming a well-developed turbulent plume, is clearly identified by the multiscale complexity-entropy causality plane.
Collapse
Affiliation(s)
- Kazushi Takagi
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Hiroshi Gotoda
- Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Isao T Tokuda
- Department of Mechanical Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| | - Takaya Miyano
- Department of Mechanical Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| |
Collapse
|