Journal of Hydrodynamics最新文献_第8页

Predicting submerged vegetation drag with a machine learning-based method 用基于机器学习的方法预测水下植被阻力

IF 2.5 3区工程技术

Journal of Hydrodynamics Pub Date : 2024-07-05 DOI: 10.1007/s42241-024-0034-6

Meng-yang Liu, Hong-wu Tang, Sai-yu Yuan, Jing Yan

{"title":"Predicting submerged vegetation drag with a machine learning-based method","authors":"Meng-yang Liu, Hong-wu Tang, Sai-yu Yuan, Jing Yan","doi":"10.1007/s42241-024-0034-6","DOIUrl":"10.1007/s42241-024-0034-6","url":null,"abstract":"<div>Accurate estimation of the drag forces generated by vegetation stems is crucial for the comprehensive assessment of the impact of aquatic vegetation on hydrodynamic processes in aquatic environments. The coupling relationship between vegetation layer flow velocity and vegetation drag makes precise prediction of submerged vegetation drag forces particularly challenging. The present study utilized published data on submerged vegetation drag force measurements and employed a genetic programming (GP) algorithm, a machine learning technique, to establish the connection between submerged vegetation drag forces and flow and vegetation parameters. When using the bulk velocity, U, as the reference velocity scale to define the drag coefficient, Cd, and stem Reynolds number, the GP runs revealed that the drag coefficient of submerged vegetation is related to submergence ratio (H*), aspect ratio (d*), blockage ratio (ψ*), and vegetation density (λ). The relation between vegetation stem drag forces and flow velocity is implicitly embedded in the definition of Cd. Comparisons with experimental drag force measurements indicate that using the bulk velocity as the reference velocity, as opposed to using the vegetation layer average velocity, Uv, eliminates the need for complex iterative processes to estimate Uv and avoids introducing additional errors associated with Uv estimation. This approach significantly enhances the model’s predictive capabilities and results in a simpler and more user-friendly formula expression.</div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"36 3","pages":"534 - 545"},"PeriodicalIF":2.5,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141587931","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

Effect of the yaw angle on turbulent flow structures around the submarine model 偏航角对潜艇模型周围湍流结构的影响

IF 2.5 3区工程技术

Journal of Hydrodynamics Pub Date : 2024-07-05 DOI: 10.1007/s42241-024-0036-4

Yi-jing Hu, Yi Qu, Qin Wu, Biao Huang

{"title":"Effect of the yaw angle on turbulent flow structures around the submarine model","authors":"Yi-jing Hu, Yi Qu, Qin Wu, Biao Huang","doi":"10.1007/s42241-024-0036-4","DOIUrl":"10.1007/s42241-024-0036-4","url":null,"abstract":"<div>The objective of this paper is to investigate the turbulent flow structures around the submarine model and evaluate the effect of the yaw angle on the turbulent flow characteristics. The large eddy simulation based on the boundary data immersion method is used to investigate. The computational domain consists of 1.2×108 uniformly distributed Cartesian orthogonal grid nodes to capture the basic flow characteristics around the model. The pressure coefficient, friction coefficient and wake velocity distribution are in good agreement with the experimental data. Three different types of vortex structures were mainly captured around the model, including horseshoe vortex, sail tip vortex and crossflow separation vortex. With the increase of the yaw angle, the asymmetry of the horseshoe vortex and the tip vortex gradually increases, and the vortex strength of the vortex leg on the windward of the horseshoe vortex and the vortex strength of the tip vortex also increase gradually. For the crossflow separation vortex, the flow separation zone gradually expands and migrates downstream with the increase of the yaw angle.</div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"36 3","pages":"421 - 434"},"PeriodicalIF":2.5,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141587927","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 analysis of coupled sloshing and motion of a cylindrical FPSO in regular waves 圆柱形浮式生产储油轮在规则波浪中的淤积和运动耦合数值分析

IF 2.5 3区工程技术

Journal of Hydrodynamics Pub Date : 2024-06-28 DOI: 10.1007/s42241-024-0032-8

Wei-wen Zhao, Xiao-long Yang, De-cheng Wan

引用次数: 0

Flow characteristics and bubble statistics during the fragmentation process of the ingested main cavity in plunging breaking waves 跌落式破浪中摄入的主腔破碎过程中的流动特性和气泡统计数据

IF 2.5 3区工程技术

Journal of Hydrodynamics Pub Date : 2024-06-28 DOI: 10.1007/s42241-024-0031-9

Wen-bin Zhang, Wei-wen Zhao, De-cheng Wan

{"title":"Flow characteristics and bubble statistics during the fragmentation process of the ingested main cavity in plunging breaking waves","authors":"Wen-bin Zhang, Wei-wen Zhao, De-cheng Wan","doi":"10.1007/s42241-024-0031-9","DOIUrl":"10.1007/s42241-024-0031-9","url":null,"abstract":"<div>Plunging breaking waves play an important role in the exchange of heat, momentum, and mass between the atmosphere and ocean. In this paper, a series of direct numerical simulations is conducted to investigate the fragmentation process of the ingested main cavity in plunging breaking waves. The two-phase Navier-Stokes equations are solved using the finite-volume method based on adaptive refinement meshes. The free surface is captured using a geometrical volume of fluid method. Both 2-D, 3-D simulations are conducted. Instantaneous flow fields at different stages of wave breaking are presented and quantitative analysis for bubbles is performed. The 2-D instantaneous vorticity field and local velocity field are visualized to discuss the general flow characteristics during the fragmentation process. Then a 2-D parametric study is conducted to investigate the differences in the flow characteristics during the fragmentation process under different wave parameters including initial wave steepness (ε), Bond number (Bo), and Reynolds number (Re). 3-D vortex structures are shown to further investigate the mechanisms behind the differences in the flow characteristics. The bubble size distributions under two different initial wave steepness are also discussed with their relationship to the fragmentation process of the ingested main cavity. This research offers a significant understanding of the distinct procedures and fundamental dynamics involved in wave breaking, enhancing our comprehension of this intricate event.</div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"36 3","pages":"546 - 555"},"PeriodicalIF":2.5,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141552687","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

Investigation of wake-induced vibration interference between two staggered wave-cone cylinders at subcritical Reynolds number 亚临界雷诺数下两个交错波锥筒之间的尾流诱导振动干扰研究

IF 2.5 3区工程技术

Journal of Hydrodynamics Pub Date : 2024-06-14 DOI: 10.1007/s42241-024-0028-4

Lin Zou, Di-wei Liu, Jian Liu, Hong-cheng Zuo, Yin-huan Zheng, Hao Xia

{"title":"Investigation of wake-induced vibration interference between two staggered wave-cone cylinders at subcritical Reynolds number","authors":"Lin Zou, Di-wei Liu, Jian Liu, Hong-cheng Zuo, Yin-huan Zheng, Hao Xia","doi":"10.1007/s42241-024-0028-4","DOIUrl":"10.1007/s42241-024-0028-4","url":null,"abstract":"<div>The wake induced vibration (WIV) of a one- and two-degree-of-freedom (1DOF, 2DOF) downstream wave-cone cylinder (WCC) behind a stationary equal-size upstream wave-cone cylinder in the staggered arrangement is numerically investigated at subcritical Reynolds number of 3 900 by using shear stressed transfer (SST) k - ω turbulence model. The streamwise pitch ratios (P / Dm) vary from 4 to 6 with a fixed incident angle α = 8°. Experimental measurements were also performed for the validation of the present numerical models. It is found that the largest vibration amplitude in crossflow direction occurred at P / Dm = 4, Ur =8 with small difference of streamwise vibration at P / Dm = 4, 6. Different from single wavy-cone cylinder (SWCC), the downstream flexible one of a pair staggered WCCs got larger vibration amplitude during phase switching stage instead of in-phase stage. The upstream wake will suppress the triple frequency of main frequency in the power spectra density (PSD) functions of Cl but stimulate the double one of that. An intriguing vibration mechanism happened in all 2DOF cases where the trajectory of downstream WCC is a significant ellipse rather than a figure of 8. The transformation of phase switching and the variation of the main frequency of drag coefficient (Cd) can be explained by the vortex-shedding modes of downstream WCC</div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"36 2","pages":"378 - 393"},"PeriodicalIF":2.5,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503483","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

Effect of the vortical structures on the hydrodynamic performance of a pitching hydrofoil 涡流结构对俯仰水翼流体力学性能的影响

IF 2.5 3区工程技术

Journal of Hydrodynamics Pub Date : 2024-06-14 DOI: 10.1007/s42241-024-0030-x

Rui Yuan, Hui-yun Hao, Qin Wu, Yun-qing Liu, Biao Huang

{"title":"Effect of the vortical structures on the hydrodynamic performance of a pitching hydrofoil","authors":"Rui Yuan, Hui-yun Hao, Qin Wu, Yun-qing Liu, Biao Huang","doi":"10.1007/s42241-024-0030-x","DOIUrl":"10.1007/s42241-024-0030-x","url":null,"abstract":"<div>The objective is to study the vortical structural behaviors of a transient pitching hydrofoil and their effects on the hydrodynamic performance. The pitching motion of the hydrofoil is set to pitch up with an almost constant rate from 5° to 15° and then back to 5°, with the Reynolds number 4.4×105 and the frequency 2 Hz. The results show that the main coherent structures around the pitching hydrofoil include small-scale laminar separation bubble (LSB), large-scale second vortex (SV) and trailing edge vortex (TEV) which are all vortical. The relationship between the vortical structure and the lift is investigated with the finite-domain impulse theory. It indicates that the major part of the lift is contributed by the LSB, whereas the shedding and the formation of the SV and TEV cause the fluctuation of the lift. The proper orthogonal decomposition (POD) method is applied to capture the most energetic modes, revealing that the LSB mode occupies a large amount of energy in the flow field. The dynamic mode decomposition (DMD) method accurately extracts the dominant frequency and modal characteristics, with the first mode corresponding to the mean flow, the second mode corresponding to the LSB structure and the third and fourth modes corresponding to the vortex shedding.</div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"36 2","pages":"406 - 420"},"PeriodicalIF":2.5,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503485","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

Rapid prediction of damaged ship roll motion responses in beam waves based on stacking algorithm 基于堆叠算法快速预测受损船舶在波束中的翻滚运动响应

IF 2.5 3区工程技术

Journal of Hydrodynamics Pub Date : 2024-06-14 DOI: 10.1007/s42241-024-0029-3

Xin-ran Liu, Ting-qiu Li, Zi-ping Wang

{"title":"Rapid prediction of damaged ship roll motion responses in beam waves based on stacking algorithm","authors":"Xin-ran Liu, Ting-qiu Li, Zi-ping Wang","doi":"10.1007/s42241-024-0029-3","DOIUrl":"10.1007/s42241-024-0029-3","url":null,"abstract":"<div>Accurate modeling for highly non-linear coupling of a damaged ship with liquid sloshing in waves is still of considerable interest within the computational fluid dynamics (CFD) and AI framework. This paper describes a data-driven Stacking algorithm for fast prediction of roll motion response amplitudes in beam waves by constructing a hydrodynamics model of a damaged ship based on the dynamic overlapping grid CFD technology. The general idea is to optimize various parameters varying with four types of classical base models like multi-layer perception, support vector regression, random forest, and hist gradient boosting regression. This offers several attractive properties in terms of accuracy and efficiency by choosing the standard DTMB 5415 model with double damaged compartments for validation. It is clearly demonstrated that the predicted response amplitude operator (RAO) in the regular beam waves agrees well with the experimental data available, which verifies the accuracy of the established damaged ship hydrodynamics model. Given high-quality CFD samples, therefore, implementation of the designed Stacking algorithm with its optimal combination can predict the damaged ship roll motion amplitudes effectively and accurately (e.g., the coefficient of determination 0.9926, the average absolute error 0.0955 and CPU 3s), by comparison of four types of typical base models and their various forms. Importantly, the established Stacking algorithm provides one potential that can break through problems involving the time-consuming and low efficiency for large-scale lengthy CFD simulations.</div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"36 2","pages":"394 - 405"},"PeriodicalIF":2.5,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503484","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

CFD-based hull optimization in calm water using adaptive grid deformation method 利用自适应网格变形法进行基于 CFD 的平静水域船体优化

IF 2.5 3区工程技术

Journal of Hydrodynamics Pub Date : 2024-06-06 DOI: 10.1007/s42241-024-0027-5

Shuguang Wang, Yonghwan Kim

{"title":"CFD-based hull optimization in calm water using adaptive grid deformation method","authors":"Shuguang Wang, Yonghwan Kim","doi":"10.1007/s42241-024-0027-5","DOIUrl":"10.1007/s42241-024-0027-5","url":null,"abstract":"<div>This paper presents an adaptive grid deformation technique for optimizing ship hull forms using computational fluid dynamics (CFD). The proposed method enables accurate and smooth updates of the hull surface and 3-D CFD grids in response to design variables. This technique incorporates a two-level point-transformation approach to move the grid points by a few design points. Initially, generic B-splines are utilized to transform grid points according to the displacements of the control points within a defined control box. This ensures surface modification accuracy and smoothness, similar to those provided by non-uniform rational B-splines. Subsequently, radial basis functions are used to interpolate the movements of the control points with a limited set of design points. The developed method effectively maintains the mesh quality and simulation efficiency. By applying this method to surface and grid adaptation, a regression model is proposed in the form of a second-order polynomial to represent the relationship between the geometric parameters and design variables. This polynomial is then used to introduce geometric constraints. Furthermore, a radial basis function surrogate model for the calm-water resistance is constructed to approximate the objective function. An enhanced optimization framework is proposed for CFD–based hull optimization and applied to KVLCC2 to validate its feasibility and efficiency.</div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"36 2","pages":"241 - 262"},"PeriodicalIF":2.5,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141375863","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 CFD study on the hydrodynamic response of a small-scale ice floe induced by a passing ship 关于过往船只诱发小尺度浮冰流体动力响应的 CFD 研究

IF 2.5 3区工程技术

Journal of Hydrodynamics Pub Date : 2024-05-31 DOI: 10.1007/s42241-024-0024-8

Zongyu Jiang, Spyros Hirdaris, Sasan Tavakoli, Mikko Suominen, Pentti Kujala

引用次数: 0

Calculation of ship motions in steep waves with restoring and Froude-Krylov forces on an adaptive panel mesh with Gauss and analytic integration methods 用高斯积分法和解析积分法计算自适应面板网格上带有恢复力和弗劳德-克雷洛夫力的陡波中的船舶运动

IF 2.5 3区工程技术

Journal of Hydrodynamics Pub Date : 2024-05-31 DOI: 10.1007/s42241-024-0026-6

Malwin Wermbter, Moustafa Abdel-Maksoud

{"title":"Calculation of ship motions in steep waves with restoring and Froude-Krylov forces on an adaptive panel mesh with Gauss and analytic integration methods","authors":"Malwin Wermbter, Moustafa Abdel-Maksoud","doi":"10.1007/s42241-024-0026-6","DOIUrl":"10.1007/s42241-024-0026-6","url":null,"abstract":"<div>The impulse response method is a frequently used method to calculate ship seakeeping behavior. In this paper, the restoring and Froude-Krylov calculation is conducted with constant evaluation of panel pressures as well as Gauss quadrature and an analytical integration. The applied panel grid is coarsened by an adaptive algorithm which is based on a normal vector condition. The comparison of methods is based on grid convergence studies which are followed by a verification of forces with computational fluid dynamics (CFD) results on the fixed duisburg test case in waves. Validations with experimental results in head, oblique and following waves show that all integration methods are accurate. The exact integration is numerically sensitive in some cases. Gauss quadrature is highly accurate; however, the additional effort is not beneficial since the geometrical accuracy has-stronger influence on the force amplitudes than the integration method. Adaptive grid coarsening reduces the simulation time and is accurate up to a level, where the panel length comes close the wavelength. The added resistance at the investigated Froude number of 0.05 shows higher uncertainty levels, this applies to the results of both the numerical methods and model tests.</div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"36 2","pages":"275 - 289"},"PeriodicalIF":2.5,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141188563","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