Theoretical and Computational Fluid Dynamics最新文献_第4页

Efficient harmonic resolvent analysis via time stepping 通过时间步长进行高效谐波解析器分析

IF 2.2 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2024-05-18 DOI: 10.1007/s00162-024-00694-1

Ali Farghadan, Junoh Jung, Rutvij Bhagwat, Aaron Towne

{"title":"Efficient harmonic resolvent analysis via time stepping","authors":"Ali Farghadan, Junoh Jung, Rutvij Bhagwat, Aaron Towne","doi":"10.1007/s00162-024-00694-1","DOIUrl":"10.1007/s00162-024-00694-1","url":null,"abstract":"We present an extension of the RSVD-(Delta t) algorithm initially developed for resolvent analysis of statistically stationary flows to handle harmonic resolvent analysis of time-periodic flows. The harmonic resolvent operator, as proposed by Padovan et al. (J Fluid Mech 900, 2020), characterizes the linearized dynamics of time-periodic flows in the frequency domain, and its singular value decomposition reveals forcing and response modes with optimal energetic gain. However, computing harmonic resolvent modes poses challenges due to (i) the coupling of all (N_{omega }) retained frequencies into a single harmonic resolvent operator and (ii) the singularity or near-singularity of the operator, making harmonic resolvent analysis considerably more computationally expensive than a standard resolvent analysis. To overcome these challenges, the RSVD-(Delta t) algorithm leverages time stepping of the underlying time-periodic linearized Navier–Stokes operator, which is (N_{omega }) times smaller than the harmonic resolvent operator, to compute the action of the harmonic resolvent operator. We develop strategies to minimize the algorithm’s CPU and memory consumption, and our results demonstrate that these costs scale linearly with the problem dimension. We validate the RSVD-(Delta t) algorithm by computing modes for a periodically varying Ginzburg–Landau equation and demonstrate its performance using the flow over an airfoil.\u0000","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"38 3","pages":"331 - 353"},"PeriodicalIF":2.2,"publicationDate":"2024-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141062857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical simulations of dam-break flows of viscoplastic fluids via shallow water equations 通过浅水方程对粘性流体的溃坝流进行数值模拟

IF 2.2 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2024-05-13 DOI: 10.1007/s00162-024-00696-z

David Kibe Muchiri, James N. Hewett, Mathieu Sellier, Miguel Moyers-Gonzalez, Jerome Monnier

{"title":"Numerical simulations of dam-break flows of viscoplastic fluids via shallow water equations","authors":"David Kibe Muchiri, James N. Hewett, Mathieu Sellier, Miguel Moyers-Gonzalez, Jerome Monnier","doi":"10.1007/s00162-024-00696-z","DOIUrl":"10.1007/s00162-024-00696-z","url":null,"abstract":"This paper presents simulations of dam-break flows of Herschel–Bulkley viscoplastic fluids over complex topographies using the shallow water equations (SWE). In particular, this study aims to assess the effects of rheological parameters: power-law index (n), consistency index (K), and yield stress ((tau _{c})), on flow height and velocity over different topographies. Three practical examples of dam-break flow cases are considered: a dam-break on an inclined flat surface, a dam-break over a non-flat topography, and a dam-break over a wet bed (downstream containing an initial fluid level). The effects of bed slope and depth ratios (the ratio between upstream and downstream fluid levels) on flow behaviour are also analyzed. The numerical results are compared with experimental data from the literature and are found to be in good agreement. Results show that for both dry and wet bed conditions, the fluid front position, peak height, and mean velocity decrease when any of the three rheological parameters are increased. However, based on a parametric sensitivity analysis, the power-law index appears to be the dominant factor in dictating fluid behaviour. Moreover, by increasing the bed slope and/or depth ratio, the wave-frontal position moves further downstream. Furthermore, the presence of an obstacle is observed to cause the formation of an upsurge that moves in the upstream direction, which increases by increasing any of the three rheological parameters. This study is useful for an in-depth understanding of the effects of rheology on catastrophic gravity-driven flows of non-Newtonian fluids (like lava or mud flows) for risk assessment and mitigation.\u0000","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"38 4","pages":"557 - 581"},"PeriodicalIF":2.2,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-024-00696-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140934803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The fluidic pinball with symmetric forcing displays steady, periodic, quasi-periodic, and chaotic dynamics 具有对称强迫的流体弹球显示出稳定、周期、准周期和混沌动力学特性

IF 2.2 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2024-05-01 DOI: 10.1007/s00162-024-00693-2

Yanting Liu, Nan Deng, Bernd R. Noack, Xin Wang

{"title":"The fluidic pinball with symmetric forcing displays steady, periodic, quasi-periodic, and chaotic dynamics","authors":"Yanting Liu, Nan Deng, Bernd R. Noack, Xin Wang","doi":"10.1007/s00162-024-00693-2","DOIUrl":"10.1007/s00162-024-00693-2","url":null,"abstract":"We numerically investigate the fluidic pinball under symmetric forcing and find seven flow regimes under different rotation speeds. The fluidic pinball consists of three rotatable cylinders placed at the vertices of an equilateral triangle pointing upstream in a uniform oncoming flow. The starting point is the unforced asymmetric periodic vortex shedding at Reynolds number Re = 100 based on the cylinder diameter. The flow is symmetrically actuated by rotating the two rear cylinders at constant speed |b| up to three times the oncoming velocity in both directions. Counterclockwise (b > 0) and clockwise (b < 0) rotation of the bottom cylinder correspond to boat tailing and base bleeding, respectively. A total of seven distinct flow regimes are observed, including a steady flow, three symmetric/asymmetric periodic types of shedding, two symmetric/asymmetric quasi-periodic behaviors, and a chaotic dynamics. The vortex shedding features multiple coupled oscillator modes, including in-phase, anti-phase, and out-of-phase synchronization and non-synchronization. These shedding regimes are analyzed employing the temporal evolution of the aerodynamic forces and a dynamical mode decomposition of the wake flow. The kaleidoscope of unforced and forced dynamics promotes the fluidic pinball as a challenging modeling and control benchmark.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"38 2","pages":"203 - 223"},"PeriodicalIF":2.2,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140828280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A one-dimensional mathematical model for shear-induced droplet formation in co-flowing fluids 共流流体中剪切诱导液滴形成的一维数学模型

IF 2.2 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2024-04-22 DOI: 10.1007/s00162-024-00690-5

Darsh Nathawani, Matthew Knepley

{"title":"A one-dimensional mathematical model for shear-induced droplet formation in co-flowing fluids","authors":"Darsh Nathawani, Matthew Knepley","doi":"10.1007/s00162-024-00690-5","DOIUrl":"10.1007/s00162-024-00690-5","url":null,"abstract":"Shear-induced droplet formation is important in many industrial applications, primarily focusing on droplet sizes and pinch-off frequency. We propose a one-dimensional mathematical model that describes the effect of shear forces on the droplet interface evolution. The aim of this paper is to simulate paraffin wax droplets in a co-flowing fluid using the proposed model to estimate the droplet volume rate for different flow velocities. Thus, the study focuses only on the dripping regime. This one-dimensional model has a single parameter that arises from the force balance on the interface. This parameter is related to the shear layer thickness and hence influenced by the change in quantities like velocity, viscosity, and surface tension. The correlation describing the dependence of the parameter on these quantities using non-dimensional numbers is presented. The model is then cross-validated with the previous computational and experimental data. We use PETSc, an open-source solver toolkit, to implement our model using a mixed finite element discretization. We present the simulation results for liquid paraffin wax under fast-moving airflow with a range of velocities.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"38 2","pages":"185 - 201"},"PeriodicalIF":2.2,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140802254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Contribution of wedge and bulk viscous forces in droplets moving on inclined surfaces 在倾斜表面上运动的液滴中楔形粘滞力和体积粘滞力的贡献

IF 2.2 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2024-04-17 DOI: 10.1007/s00162-024-00692-3

Francisco Bodziony, Xiaomei Li, Mariana Yin, Rüdiger Berger, Hans-Jürgen Butt, Holger Marschall

引用次数: 0

Modal-based generalised quasilinear approximations for turbulent plane Couette flow 基于模态的平面库埃特湍流广义准线性近似方法

IF 2.2 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2024-04-15 DOI: 10.1007/s00162-024-00691-4

Igor A. Maia, André V. G. Cavalieri

{"title":"Modal-based generalised quasilinear approximations for turbulent plane Couette flow","authors":"Igor A. Maia, André V. G. Cavalieri","doi":"10.1007/s00162-024-00691-4","DOIUrl":"10.1007/s00162-024-00691-4","url":null,"abstract":"We study generalised quasilinear (GQL) approximations applied to turbulent plane Couette flow. The GQL framework is explored in conjunction with a Galerkin reduced-order model (ROM) recently developed by Cavalieri and Nogueira (Phys Rev Fluids 7:102601, 2022), which considers controllability modes of the linearised Navier–Stokes system as basis functions, representing coherent structures in the flow. The velocity field is decomposed into two groups: one composed by high-controllability modes and the other by low-controllability modes. The former group is solved with the full nonlinear equations, whereas the equations for the latter are linearised. We also consider a new GQL framework wherein the linearised equations for the low-controllability modes are driven by nonlinear interactions of modes in the first group, which are characterised by large-scale coherent structures. It is shown that GQL-ROMs successfully recover the statistics of the full model with relatively high controllability thresholds and sparser nonlinear operators. Driven GQL-ROMs were found to converge more rapidly than standard GQL approximations, providing accurate description of the statistics with a larger number of linearised modes. This indicates that the forcing of linearised flow structures by large-scale coherent structures is an important feature of turbulence dynamics that should be considered in GQL models. The results presented here reveal that further model reductions are attainable with GQL-ROMs, which can be valuable to extend these models to larger Reynolds numbers.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"38 3","pages":"313 - 330"},"PeriodicalIF":2.2,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140581888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Resolvent model for aeroacoustics of trailing edge noise 后缘噪声的航空声学驻留模型

IF 2.2 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2024-04-08 DOI: 10.1007/s00162-024-00688-z

S. Demange, Z. Yuan, S. Jekosch, A. Hanifi, A. V. G. Cavalieri, E. Sarradj, T. L. Kaiser, K. Oberleithner

{"title":"Resolvent model for aeroacoustics of trailing edge noise","authors":"S. Demange, Z. Yuan, S. Jekosch, A. Hanifi, A. V. G. Cavalieri, E. Sarradj, T. L. Kaiser, K. Oberleithner","doi":"10.1007/s00162-024-00688-z","DOIUrl":"10.1007/s00162-024-00688-z","url":null,"abstract":"This study presents a physics-based, low-order model for the trailing edge (TE) noise generated by an airfoil at low angle of attack. The approach employs incompressible resolvent analysis of the mean flow to extract relevant spanwise-coherent structures in the transitional boundary layer and near wake. These structures are integrated into Curle’s solution to Lighthill’s acoustic analogy to obtain the scattered acoustic field. The model has the advantage of predicting surface pressure fluctuations from first principles, avoiding reliance on empirical models, but with a free amplitude set by simulation data. The model is evaluated for the transitional flow ((text {Re} = 5e4)) around a NACA0012 airfoil at 3 deg angle of attack, which features TE noise with multiple tones. The mean flow is obtained from a compressible large eddy simulation, and spectral proper orthogonal decomposition (SPOD) is employed to extract the main hydrodynamic and acoustic features of the flow. Comparisons between resolvent and SPOD demonstrate that the physics-based model accurately captures the leading coherent structures at the main tones’ frequencies, resulting in a good agreement of the reconstructed acoustic power with that of the SPOD (within 4 dB). Discrepancies are observed at high frequencies, likely linked to nonlinearities that are not considered in the resolvent analysis. The model’s directivity aligns well with the data at low Helmholtz numbers, but it fails at high frequencies where the back-scattered pressure plays a significant role in directivity. This modeling approach opens the way for efficient optimization of airfoil shapes in combination with low-fidelity mean flow solvers to reduce TE noise.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"38 2","pages":"163 - 183"},"PeriodicalIF":2.2,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-024-00688-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140581827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Analysis of transient and intermittent flows using a multidimensional empirical mode decomposition 利用多维经验模式分解分析瞬态和间歇流动

IF 2.2 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2024-04-01 DOI: 10.1007/s00162-024-00689-y

Lucas F. de Souza, Renato F. Miotto, William R. Wolf

{"title":"Analysis of transient and intermittent flows using a multidimensional empirical mode decomposition","authors":"Lucas F. de Souza, Renato F. Miotto, William R. Wolf","doi":"10.1007/s00162-024-00689-y","DOIUrl":"10.1007/s00162-024-00689-y","url":null,"abstract":"Modal decomposition techniques are important tools for the analysis of unsteady flows and, in order to provide meaningful insights with respect to coherent structures and their characteristic frequencies, the modes must possess a robust spatial support. In this context, although widely used, methods based on singular value decomposition (SVD) may produce modes that are difficult to interpret when applied to problems dominated by intermittent and transient events. Fortunately, specific modal decomposition techniques have been recently developed to analyze such problems, but a proper comparison between them is still lacking from the literature. Therefore, this work compares two recent methods: the fast adaptive multivariate empirical mode decomposition (FA-MVEMD) and the multiresolution dynamic mode decomposition (mrDMD). These techniques are employed here for the study of flow databases involving transient and intermittent dynamics. Specifically, the investigated problems include an SD7003 airfoil subjected to deep dynamic stall conditions, and a steady NACA0012 airfoil operating at a transitional Reynolds number. In the former case, the methods are employed to investigate the onset and evolution of the dynamic stall vortex (DSV), while in the latter case, intermittent vortex pairing is analyzed. We show that the combination of a multidimensional EMD with the Hilbert transform provides modes with superior spatial support when compared to the mrDMD, also allowing the characterization of instantaneous frequencies of coherent structures. Moreover, the EMD also condenses a larger amount of information within a single intrinsic mode function (IMF).","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"38 3","pages":"291 - 311"},"PeriodicalIF":2.2,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140582022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Wavy ground effects on the stability of cylinder wakes 地面波浪对气缸摆动稳定性的影响

IF 2.2 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2024-02-21 DOI: 10.1007/s00162-024-00687-0

M. Duran, E. Ferrer, S. Bhattacharya

{"title":"Wavy ground effects on the stability of cylinder wakes","authors":"M. Duran, E. Ferrer, S. Bhattacharya","doi":"10.1007/s00162-024-00687-0","DOIUrl":"10.1007/s00162-024-00687-0","url":null,"abstract":"The stability of the flow past a circular cylinder in the presence of a wavy ground is investigated numerically in this paper. The wavy ground consists of two complete waves with a wavelength of 4D and an amplitude of 0.5D, where D is the cylinder diameter. The vertical distance between the cylinder and the ground is varied, and four different cases are considered. The stability analysis shows that the critical Reynolds number increases for cases close to the ground when compared to the flow past a cylinder away from the ground. The maximum critical Reynolds number is obtained when the cylinder is located in front of the waves. The wavy ground adds layers of clockwise (negative) vorticity due to flow separation from the wave peak, to the oscillating Kármán vortex. This negative vorticity from the wave peak also cancels part of the positive (counterclockwise) vorticity shed from the bottom half of the cylinder. In addition, the negative vorticity from the wave peak strengthens the clockwise (negative) vorticity shed from the top half of the cylinder. These interactions combined with the ground effect skewed the flow away from the ground. The base flow is skewed upward for all the near-ground cases. However, this skew is larger when the cylinder is located over the wavy ground. The vortex shedding frequency is also altered due to the presence of the waves. The main eigenmode found for plain flow past a cylinder appears to become suppressed for cases closer to the ground. Limited particle image velocimetry experiments are reported which corroborate the finding from the stability analysis.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"38 2","pages":"139 - 162"},"PeriodicalIF":2.2,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139921109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Simulation of the unsteady vortical flow of freely falling plates 自由落体板块的非稳态涡流模拟

IF 2.2 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2024-02-14 DOI: 10.1007/s00162-024-00686-1

Sung-Ik Sohn

引用次数: 0