Theoretical and Computational Fluid Dynamics最新文献_第7页

A numerical framework for linear stability analysis of two-phase stratified pipe flows 两相分层管流线性稳定性分析的数值框架

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2023-07-13 DOI: 10.1007/s00162-023-00667-w

Ilya Barmak, Alexander Gelfgat, Neima Brauner

{"title":"A numerical framework for linear stability analysis of two-phase stratified pipe flows","authors":"Ilya Barmak, Alexander Gelfgat, Neima Brauner","doi":"10.1007/s00162-023-00667-w","DOIUrl":"10.1007/s00162-023-00667-w","url":null,"abstract":"A numerical framework for rigorous linear stability analysis of two-phase stratified flows of two immiscible fluids in horizontal circular pipes is presented. For the first time, three-dimensional disturbances, including those at the interface between two fluids, are considered. The proposed numerical framework is based on a finite volume method and allows solving the problem numerically in bipolar cylindrical coordinates. In these coordinates, both the pipe wall and the unperturbed interface (of a constant curvature, e.g., plane interface, as considered in this work) coincide with the coordinate surfaces. Thereby, the no-slip as well as the interfacial boundary conditions can be imposed easily. It also enables investigation of the local behavior of the flow field and shear stresses in the vicinity of the triple points, where the interface contacts the pipe wall. The results obtained in the bipolar coordinates are verified by an independent numerical solution based on the problem formulation in Cartesian coordinates, where the pipe wall is treated by the immersed boundary method. Two representative examples of gas–liquid and liquid–liquid flows are included to demonstrate the applicability of the proposed numerical technique for analyzing the flow stability.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"37 5","pages":"559 - 587"},"PeriodicalIF":3.4,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42608436","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

Linear stability of a counter-rotating vortex pair approaching an inviscid wall 接近无粘壁面的反向旋转涡对的线性稳定性

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2023-06-27 DOI: 10.1007/s00162-023-00660-3

Mark A. Herndon, Justin W. Jaworski

{"title":"Linear stability of a counter-rotating vortex pair approaching an inviscid wall","authors":"Mark A. Herndon, Justin W. Jaworski","doi":"10.1007/s00162-023-00660-3","DOIUrl":"10.1007/s00162-023-00660-3","url":null,"abstract":"The influence of an inviscid planar wall on the temporal development of the long-wavelength instability of a trailing vortex pair is formulated analytically and studied numerically. The center positions and deformation perturbations of the trailing vortices are marched forward in time via the vortex filament method based on Biot–Savart induction. An optimal perturbation analysis of the vortex system determines the wavenumber and initial condition that yield maximum perturbation growth for any instant in time. Direct integration of the vortex system highlights its sensitivity to initial conditions and the time dependence of the optimal wavenumber, which are not features of the classical free vortex pair. As the counter-rotating vortex pair approaches the wall, the wavenumber for maximum growth shifts to a higher value than what is predicted for the Crow instability of vortices in an unbounded fluid. The present analysis demonstrates that the local suppression of the Crow instability near a planar wall may be described without recourse to viscous fluid arguments.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"37 4","pages":"519 - 532"},"PeriodicalIF":3.4,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-023-00660-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5047890","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

Vortex interactions of two burst-and-coast swimmers in a side-by-side arrangement 两个冲岸游泳者并排排列的涡旋相互作用

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2023-06-24 DOI: 10.1007/s00162-023-00664-z

Li-Ming Chao, Amneet Pal Singh Bhalla, Liang Li

引用次数: 0

Effects of wavelength on vortex structure and turbulence kinetic energy transfer of flow over undulated cylinders 波长对波动圆柱上流动涡流结构和湍流动能传递的影响

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2023-06-18 DOI: 10.1007/s00162-023-00661-2

Kathleen Lyons, Raúl Bayoán Cal, Jennifer A. Franck

{"title":"Effects of wavelength on vortex structure and turbulence kinetic energy transfer of flow over undulated cylinders","authors":"Kathleen Lyons, Raúl Bayoán Cal, Jennifer A. Franck","doi":"10.1007/s00162-023-00661-2","DOIUrl":"10.1007/s00162-023-00661-2","url":null,"abstract":"Passive flow control is commonly used on bluff bodies for drag and oscillating lift reduction across a range of engineering applications. This research explores a spanwise undulated cylinder inspired by seal whiskers that is shown to reduce hydrodynamic forces when compared to smooth cylinders. Although the fluid flow over this complex geometry has been documented experimentally and computationally, investigations surrounding geometric modifications to the undulation topography have been limited, and fluid mechanisms by which force reduction is induced have not been fully examined. Five variations of undulation wavelength are simulated at Reynolds number (text {Re}=250) and compared with results from a smooth elliptical cylinder. Vortex structures and turbulence kinetic energy (TKE) transfer in the wake are analyzed to explain how undulation wavelength affects force reduction. Modifications to the undulation wavelength generate a variety of flow patterns including alternating vortex rollers and hairpin vortices. Maximum force reduction is observed at wavelengths that are large enough to allow hairpin vortices to develop without intersecting each other and small enough to prevent the generation of additional alternating flow structures. The differences in flow structures modify the magnitude and location of TKE production and dissipation due to changes in mean and fluctuating strain. Decreased TKE production and increased dissipation in the near wake result in overall lower TKE and force reduction. Understanding the flow physics linking geometry to force reduction will guide appropriate parameter selection in bio-inspired design applications.\u0000","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"37 4","pages":"485 - 504"},"PeriodicalIF":3.4,"publicationDate":"2023-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4725044","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: 2

Super-resolution analysis via machine learning: a survey for fluid flows 通过机器学习的超分辨率分析:对流体流动的调查

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2023-06-16 DOI: 10.1007/s00162-023-00663-0

Kai Fukami, Koji Fukagata, Kunihiko Taira

引用次数: 14

Design of optimal wing maneuvers in a transverse gust encounter through iterated simulation or experiment 通过反复模拟或实验设计横向阵风遭遇时的最佳机翼机动

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2023-06-15 DOI: 10.1007/s00162-023-00659-w

Xianzhang Xu, Antonios Gementzopoulos, Girguis Sedky, Anya R. Jones, Francis D. Lagor

{"title":"Design of optimal wing maneuvers in a transverse gust encounter through iterated simulation or experiment","authors":"Xianzhang Xu, Antonios Gementzopoulos, Girguis Sedky, Anya R. Jones, Francis D. Lagor","doi":"10.1007/s00162-023-00659-w","DOIUrl":"10.1007/s00162-023-00659-w","url":null,"abstract":"Wing–gust encounters cause harmful lift transients that can be mitigated through maneuvering of the wing. This paper presents a method to generate an open-loop (i.e., prescribed) maneuver that optimally regulates the lift on the wing during a transverse gust encounter. Obtaining an optimal maneuver is important for laboratory experiments on the physics of wing–gust interactions and may be useful for the future design of feedback controllers. Prior work of the authors has shown that an Iterative Maneuver Optimization (IMO) framework can generate an optimal maneuver by using a surrogate model to propose a control signal that is then tested in experiment or high-fidelity simulation. The input to the surrogate model is updated to account for differences between the test data and the expected output. The optimal maneuver is obtained through iteration of this process. This paper simplifies the IMO method by replacing the surrogate model with the classical lift model of Theodorsen, removing the process of optimization over the surrogate model, and removing the requirement to know the time-averaged profile of the gust. The proposed method, referred to as Simplified IMO (SIMO), only requires input and output data collected from simulations or experiments that interact with the gust. Numerical simulations using a Leading Edge Suction Parameter modulated Discrete Vortex Model are presented to generate the input and output data of the wing–gust encounters for this paper. Experiments in a towing tank also validated the SIMO method. The results show an optimal pitch maneuver and an optimal plunge maneuver that can each regulate lift during a transverse gust encounter.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"37 4","pages":"465 - 484"},"PeriodicalIF":3.4,"publicationDate":"2023-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-023-00659-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4903585","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

Monte Carlo simulation of the coffee-ring effect on porous papers 多孔纸上咖啡环效应的蒙特卡罗模拟

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2023-06-15 DOI: 10.1007/s00162-023-00662-1

Youngjin Hwang, Sangkwon Kim, Chaeyoung Lee, Soobin Kwak, Gyeonggyu Lee, Junseok Kim

引用次数: 0

Receptivity of high-speed boundary layer on a flat plate at angles of attack: entropy and vorticity waves 迎角下平板上高速边界层的接受度:熵波和涡量波

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2023-06-09 DOI: 10.1007/s00162-023-00656-z

Alexander V. Fedorov, Natalia Palchekovskaya

{"title":"Receptivity of high-speed boundary layer on a flat plate at angles of attack: entropy and vorticity waves","authors":"Alexander V. Fedorov, Natalia Palchekovskaya","doi":"10.1007/s00162-023-00656-z","DOIUrl":"10.1007/s00162-023-00656-z","url":null,"abstract":"In the paper (Theoret Comput Fluid Dyn 36:705–722, 2022), we analyzed acoustic receptivity of the boundary layer on a flat plate in Mach 6 flow at various angles of attack (AoA). It was shown that slow and fast acoustic waves passing through: a bow shock at AoA(=-5^{circ }), a weak shock induced by the viscous–inviscid interaction at AoA(=0^{circ }), or an expansion fan at AoA( = 5^{circ }), excite dominant modes F and S in a small vicinity of the plate leading edge. The present paper extends this analysis to the cases of receptivity to entropy and vorticity waves. Similar to the case of acoustic receptivity, modes F and S of about equal amplitude are excited in a small vicinity of the plate leading edge. These modes propagate downstream in accord with the two-mode approximation model accounting for the mean-flow nonparallel effects and the intermodal exchange mechanism. Cross-comparisons of the initial amplitudes of excited modes help to evaluate the relative role of acoustic, entropy and vorticity waves in the second-mode dominated transition.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"37 5","pages":"549 - 558"},"PeriodicalIF":3.4,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47763279","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

Sparse sensor reconstruction of vortex-impinged airfoil wake with machine learning 基于机器学习的涡碰翼型尾迹稀疏传感器重建

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2023-06-07 DOI: 10.1007/s00162-023-00657-y

Yonghong Zhong, Kai Fukami, Byungjin An, Kunihiko Taira

{"title":"Sparse sensor reconstruction of vortex-impinged airfoil wake with machine learning","authors":"Yonghong Zhong, Kai Fukami, Byungjin An, Kunihiko Taira","doi":"10.1007/s00162-023-00657-y","DOIUrl":"10.1007/s00162-023-00657-y","url":null,"abstract":"Reconstruction of unsteady vortical flow fields from limited sensor measurements is challenging. We develop machine learning methods to reconstruct flow features from sparse sensor measurements during transient vortex–airfoil wake interaction using only a limited amount of training data. The present machine learning models accurately reconstruct the aerodynamic force coefficients, pressure distributions over airfoil surface, and two-dimensional vorticity field for a variety of untrained cases. Multi-layer perceptron is used for estimating aerodynamic forces and pressure profiles over the surface, establishing a nonlinear model between the pressure sensor measurements and the output variables. A combination of multi-layer perceptron with convolutional neural network is utilized to reconstruct the vortical wake. Furthermore, the use of transfer learning and long short-term memory algorithm combined in the training models greatly improves the reconstruction of transient wakes by embedding the dynamics. The present machine-learning methods are able to estimate the transient flow features while exhibiting robustness against noisy sensor measurements. Finally, appropriate sensor locations over different time periods are assessed for accurately estimating the wakes. The present study offers insights into the dynamics of vortex–airfoil interaction and the development of data-driven flow estimation.\u0000","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"37 2","pages":"269 - 287"},"PeriodicalIF":3.4,"publicationDate":"2023-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-023-00657-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4310286","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: 7

Stabilization of crossflow mode by grooves on a supersonic swept wing 超音速后掠翼沟槽稳定化横流模态

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2023-06-01 DOI: 10.1007/s00162-023-00658-x

Alexander Fedorov, Andrey Novikov

引用次数: 0