Recent advances in feature extraction techniques for high-speed flowfields

Unnikrishnan, S.

doi:10.1016/j.paerosci.2023.100918

Cited by 6 publications

(2 citation statements)

References 202 publications

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“…This paper reviews the recent advancements in the physics and modeling of high-speed wall-bounded transitional and turbulent flows. There have been a number of comprehensive reviews in recent years on the high-speed flow transition [28][29][30][31][32][33][34][35][36], so the main focus of this paper is on the high-speed turbulence; the transition part will also be briefly summarized, considering the integrity of the physical process. The remaining parts will be organized as follows.…”

Section: Introductionmentioning

confidence: 99%

Progress in physical modeling of compressible wall-bounded turbulent flows

Cheng,

Chen,

Zhu

et al. 2024

Acta Mech. Sin.

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Understanding, modeling and control of the high-speed wall-bounded transition and turbulence not only receive wide academic interests but also are vitally important for high-speed vehicle design and energy saving because transition and turbulence can induce significant surface drag and heat transfer. The high-speed flows share some fundamental similarities with the incompressible counterparts according to Morkovin’s hypothesis, but there are also significant distinctions resulting from multi-physics coupling with thermodynamics, shocks, high-enthalpy effects, and so on. In this paper, the recent advancements on the physics and modeling of high-speed wall-bounded transitional and turbulent flows are reviewed; most parts are covered by turbulence studies. For integrity of the physical process, we first briefly review the high-speed flow transition, with the main focus on aerodynamic heating mechanisms and passive control strategies for transition delay. Afterward, we summarize recent encouraging findings on turbulent mean flow scaling laws for streamwise velocity and temperature, based on which a series of unique wall models are constructed to improve the simulation accuracy. As one of the foundations for turbulence modeling, the research survey on turbulent structures is also included, with particular focus on the scaling and modeling of energy-containing motions in the logarithmic region of boundary layers. Besides, we review a variety of linear models for predicting wall-bounded turbulence, which have achieved a great success over the last two decades, though turbulence is generally believed to be highly nonlinear. In the end, we conclude the review and outline future works.

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Section: Introductionmentioning

confidence: 99%

Progress in physical modeling of compressible wall-bounded turbulent flows

Cheng,

Chen,

Zhu

et al. 2024

Acta Mech. Sin.

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“…The selection of informative attributes is key to SHM DOI: 10.1002/masy.202400044 efficiency. [3][4][5] Dimensionality reduction (DR) techniques are favored for simplifying complex, high-dimensional data, maintaining essential information. The choice of DR approach greatly impacts SHM performance, with suitable approaches enhancing malfunction identification and inappropriate ones risking information loss and inaccurate assessments.…”

Section: Introductionmentioning

confidence: 99%

Dimensionality Reduction in Structural Health Monitoring: A Case Study on Damaged Wind Turbine Blades

Rezazadeh,

Polverino,

Perfetto

et al. 2024

Macromolecular Symposia

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In recent years, advances in structural health monitoring (SHM) of composite materials have been observed, driven by the adoption of intelligent diagnostic techniques. Vibration signals, which embed valuable structural health information, have been increasingly utilized in SHM. However, the high dimensionality of this data has necessitated significant computational resources and has made the differentiation between health states more complex. Highlighting the need for effective feature extraction and dimensionality reduction (DR), a study is conducted. In this research, advanced DR techniques, i.e., principal component analysis (PCA), locally linear embedding (LLE), t‐distributed stochastic neighbors embedding (t‐SNE), and uniform manifold approximation and projection (UMAP), are applied to an experimental dataset from a wind turbine blade under various health and environmental conditions (controlled‐environment vibration signals). The extracted features are then processed for the classification phase, and it is found that UMAP provides the best performance, albeit with a slightly increased computational demand. The findings from this research offer invaluable insights for researchers and engineers, assisting in the selection of the most appropriate DR method for SHM, and weighing up accuracy against computational time.

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An invitation to resolvent analysis

Rolandi,

Ribeiro,

Yeh

et al. 2024

Theor. Comput. Fluid Dyn.

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Resolvent analysis is a powerful tool that can reveal the linear amplification mechanisms between the forcing inputs and the response outputs about a base flow. These mechanisms can be revealed in terms of a pair of forcing and response modes and the associated energy gains (amplification magnitude) at a given frequency. The linear relationship that ties the forcing and the response is represented through the resolvent operator (transfer function), which is constructed through spatially discretizing the linearized Navier–Stokes operator. One of the unique strengths of resolvent analysis is its ability to analyze statistically stationary turbulent flows. In light of the increasing interest in using resolvent analysis to study a variety of flows, we offer this guide in hopes of removing the hurdle for students and researchers to initiate the development of a resolvent analysis code and its applications to their problems of interest. To achieve this goal, we discuss various aspects of resolvent analysis and its role in identifying dominant flow structures about the base flow. The discussion in this paper revolves around the compressible Navier–Stokes equations in the most general manner. We cover essential considerations ranging from selecting the base flow and appropriate energy norms to the intricacies of constructing the linear operator and performing eigenvalue and singular value decompositions. Throughout the paper, we offer details and know-how that may not be available to readers in a collective manner elsewhere. Towards the end of this paper, examples are offered to demonstrate the practical applicability of resolvent analysis, aiming to guide readers through its implementation and inspire further extensions. We invite readers to consider resolvent analysis as a companion for their research endeavors.

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Recent advances in feature extraction techniques for high-speed flowfields

Cited by 6 publications

References 202 publications

Progress in physical modeling of compressible wall-bounded turbulent flows

Progress in physical modeling of compressible wall-bounded turbulent flows

Dimensionality Reduction in Structural Health Monitoring: A Case Study on Damaged Wind Turbine Blades

An invitation to resolvent analysis

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