Journal of Hydrodynamics最新文献

{"title":"Acoustic streaming enhanced micromixing in microfluidic channels","authors":"Yi-ming Li,&nbsp;Ze-kai Li,&nbsp;Dongfang Liang,&nbsp;Bochen Gao,&nbsp;Chen Fu","doi":"10.1007/s42241-026-0024-y","DOIUrl":"10.1007/s42241-026-0024-y","url":null,"abstract":"<div><p>Efficient mixing in microfluidic channels is hindered by the small diffusion coefficient. In this study, we exploit surface acoustic wave (SAW) induced microstreaming to achieve rapid mixing of two co-flowing miscible streams within a microchannel. Three SAW actuation strategies are introduced and systematically investigated: one-side standing SAW (bottom-SSAW), two-side standing SAW, and two-side travelling SAW. To examine the first-order acoustic field, the second-order streaming flow, and the mixing performance under different SAW configurations, we develop a 3-D computational model based on the finite element method (FEM), which solves the periodic acoustic and time-averaged Rayleigh streaming fields in the frequency domain via the perturbation method. The resulting flow is then coupled with a convection-diffusion model for investigating species transport characteristics. The results show that the two-side standing SAW setup yields the strongest streaming, forming a vertically and laterally symmetric streaming field in a cross section with four bulk vortices, while the two-side travelling SAW setup introduces a centrally patterned, dominant streaming vortex that provides efficient transverse advection despite a slightly lower streaming velocity. In contrast, the conventional bottom-SSAW configuration produces weak, asymmetric streaming. For mixing applications, both two-side SAW configurations demonstrate outstanding performance with over 90% mixing efficiency at a flow rate up to ∼1 µL/min, significantly outperforming the bottom-SSAW configuration (∼60% at 1 µL/min). Our findings provide guidelines for the design of high-throughput, efficient, and versatile acoustofluidic micromixers.</p></div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"38 1","pages":"87 - 94"},"PeriodicalIF":3.5,"publicationDate":"2026-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148061081","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}

{"title":"On the transient stress field of an ellipsoidal stone in a lithotripter shockwave field in water","authors":"Gao-ming Xiang,&nbsp;Jia-yue Yang,&nbsp;Lin-hua Liu","doi":"10.1007/s42241-026-0023-z","DOIUrl":"10.1007/s42241-026-0023-z","url":null,"abstract":"<div><p>Shock wave lithotripsy has been widely used in treating kidney stones due to its noninvasive procedure over the past decades. However, the treatment outcome is affected by multiple factors and the physical mechanism underlying the fluid-solid coupling between the lithotripter shock wave (LSW) and the solid stone is not sufficiently understood. Considering that a kidney stone usually displays an irregular shape, we perform numerical studies on the dynamic fluid-solid interaction between the LSW and an ellipsoidal solid stone. Our results suggest that the stress field during the dynamic shock loading condition on an ellipsoidal solid stone can be categorized into three types depending on the axis ratio, including Type I (flattened stone), Type II (circular stone) and Type III (elongated stone). For the flattened stones, geometrical focus mainly occurs near the anterior surface of the solid, while for the circular and elongated stones, the geometrical focus mainly occurs near the lateral surface. Quantitative results show that the peak tensile stress could reach up to 220 MPa inside the stone for COM stone, and the peak stress integral <i>S</i> reaches up to 3.9×10⁹ Pa²·s. Furthermore, our simulation results also suggest that the leaky Rayleigh wave generates strong tensile stress and stress integral near the solid boundary, particularly for Type III of the elongated stones. We believe that our findings provide new insights in shock wave lithotripsy and can also be valuable in other fields, such as cavitation erosion near solid materials.</p></div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"38 1","pages":"68 - 79"},"PeriodicalIF":3.5,"publicationDate":"2026-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148060991","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}

{"title":"Investigation of jet characteristics and vortex dynamics induced by bubble collapsing near a convex wall","authors":"Jing-yin Zhang,&nbsp;Qi Liang,&nbsp;Yu-hang Liu,&nbsp;Ya-bin Liu,&nbsp;Shan Xu,&nbsp;Ke-xin Wang,&nbsp;Yu-ning Zhang","doi":"10.1007/s42241-026-0025-x","DOIUrl":"10.1007/s42241-026-0025-x","url":null,"abstract":"<div><p>Based on the high-speed photography experimental platform and open source software OpenFOAM, the collapse behavior of the cavitation bubble adjacent to a large-curvature convex wall is investigated. The influence of the wall-bubble dimensionless distance on the bubble collapse cases, jet characteristics, and vortex evolution is analyzed. The findings reveal that: (1) As the dimensionless wall-bubble distance <i>γ</i> increases, the collapse jet presents three typical cases: the single jet away from the wall, the single jet towards the wall, and the double jets. (2) The high-pressure region formed during bubble collapse transitions from the inferior lateral region to the bubble circumference as <i>γ</i> increases. (3) The vortex dynamics during bubble rebound are strongly dependent on the dimensionless distance <i>γ</i>. The wall-bound vortices that dominate at larger <i>γ</i> are caused by the rebound bubble impacting the wall.</p></div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"38 1","pages":"32 - 43"},"PeriodicalIF":3.5,"publicationDate":"2026-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148060990","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}

{"title":"Dynamics of the bubble jet and centroid motion near a semicylindrical protrusion within confined spaces","authors":"Peng Luo,&nbsp;Wen-da Liu,&nbsp;Ting-ting Zhang,&nbsp;Qi-hang Xu,&nbsp;Kang-kang Li,&nbsp;Dong-yang Zhang,&nbsp;Jun-wei Shen,&nbsp;Yu-ning Zhang","doi":"10.1007/s42241-026-0022-0","DOIUrl":"10.1007/s42241-026-0022-0","url":null,"abstract":"<div><p>The present paper conducts experimental and theoretical analyses of the cavitation bubble dynamics near a semicylindrical protrusion within a confined space. Based on the conformal transformation, the image method, and the potential flow superposition theory, a Kelvin impulse model for the cylindrical bubble is established. By comparison with the experimental results, theoretical liquid velocity and Kelvin impulse results are obtained, reflecting the characteristics of the bubble collapse jet and centroid motion, which reveals the formation mechanism of the collapse jet. The main conclusions are summarized as follows: (1) When a bubble collapses near a semicylindrical protrusion, a pronounced asymmetric splitting phenomenon occurs, primarily caused by a high-speed jet directed toward the wall surface. (2) The theoretical liquid velocity distribution can effectively predict the bubble interface motion, which is the main reason for the formation of the collapse jet. (3) The Kelvin impulse can effectively predict the bubble centroid motion.</p></div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"38 1","pages":"80 - 86"},"PeriodicalIF":3.5,"publicationDate":"2026-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148060972","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}

{"title":"Numerical analysis of impact force and motion trajectory for a biomimetic body with a deflected cone nose during high-speed water entry","authors":"Fu-ren Ming,&nbsp;Chun-hui Tao,&nbsp;Wen-tao Liu,&nbsp;Jia-jie Wang,&nbsp;Chang Liu","doi":"10.1007/s42241-026-0021-1","DOIUrl":"10.1007/s42241-026-0021-1","url":null,"abstract":"<div><p>The impact force and trajectory stability of a body entering water at high speeds are crucial for safety. This paper first extracts the biological traits of the northern gannet that contribute to reduced impact force and enhanced trajectory stability. Inspired by these traits, a biomimetic body featuring a deflected cone nose is designed. Then, using the immersed boundary method by the Eulerian finite element method (EFEM), we simulate the body’s impact force and motion trajectory under varying nose deflection and initial attitude angles. Compared with conventional nose shapes like spherical or flat nose, the cone nose, mimicking the gannet’s beak, can prolong the impact duration, thereby reducing the initial peak force during water entry. Moreover, akin to how the gannet adjusts its neck for precise fishing, adjusting the cone nose’s deflection on the biomimetic body can result in a straighter trajectory and lower normal force. The optimal deflection angle is dependent upon the initial attitude angles. This study identifies an optimal parameter range for both the initial attitude and nose deflection angles, providing valuable insights for improving force reduction and stability.</p></div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"38 1","pages":"18 - 31"},"PeriodicalIF":3.5,"publicationDate":"2026-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148061107","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}

{"title":"Experimental study on the interactions between cavitation bubbles and soft elastic boundaries","authors":"Zhi-bo He,&nbsp;Zhi-ying Zheng,&nbsp;Guan-yu An,&nbsp;Quan-zhong Liu","doi":"10.1007/s42241-026-0020-2","DOIUrl":"10.1007/s42241-026-0020-2","url":null,"abstract":"<div><p>Understanding the interaction between cavitation bubbles and a soft elastic boundary is of great practical significance in control and use of lasers and ultrasound in medical diagnosis and treatment. Experiments on laser-induced sub-millimeter (maximum radius of 390±10 µm) cavitation bubbles near soft elastic boundaries (prepared by agarose hydrogels with three concentrations, elastic modulus <i>E</i> = 11.7 kPa −130.9 kPa are carried out via high-speed photography. The influences of elastic modulus <i>E</i> and dimensionless standoff distance <i>γ</i> on the evolution, jet behavior, migration, and aspect ratio of cavitation bubbles are analyzed, together with the deformation and damage of the elastic boundary. Based on the jet behavior and boundary response, the interactions between cavitation bubbles and elastic boundaries are classified into six distinct regimes. Among these six regimes, two new dynamic characteristics are observed, including a novel boundary damage pattern caused by the explosive expansion of high-pressure gas within the boundary and a jet generated by the annular squeezing of the elastic boundary. Both the jet velocity and its penetration depth into the elastic boundary vary non-monotonically with <i>γ</i>, and each attains a maximum. For all three elastic boundaries, the corresponding <i>γ</i> values fall within the range 0.5–0.6.</p></div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"38 1","pages":"44 - 55"},"PeriodicalIF":3.5,"publicationDate":"2026-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148060533","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}

{"title":"Laboratory investigation of near-resonance stem motion and lateral dispersion in flexible aquatic canopy under surface wave action","authors":"Alireza Hadian,&nbsp;Mirmosadegh Jamali","doi":"10.1007/s42241-026-0019-8","DOIUrl":"10.1007/s42241-026-0019-8","url":null,"abstract":"<div><p>Aquatic plants have significant effects on wave dynamics and contaminant transport. Using a laboratory canopy model, we investigated the interaction of a surface wave with flexible stems with a focus on the case when the wave frequency is close to the natural frequency of stems. The experiments were conducted at various wave frequencies, wave heights, and vegetation densities of 0.8% and 1.2%. The oscillation amplitude of the stems and the lateral dispersion coefficient were measured. Image processing techniques were employed to analyze the experimental data. The results indicate that the oscillation amplitude of the stems is larger than the orbital displacement of fluid particles when the surface wave frequency approaches the natural frequency of the stems. However, the intensified longitudinal oscillation of the stems does not lead to rapid cloud expansion beyond the effects of turbulence and vortex shedding, represented by the Reynolds and Keulegan-Carpenter numbers, respectively. The results confirm that denser vegetation results in a higher transverse dispersion coefficient. By comparing with the available results for dispersion coefficient under current, we found that the lateral dispersion under wave action is much smaller than that under current.</p></div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"38 1","pages":"170 - 179"},"PeriodicalIF":3.5,"publicationDate":"2026-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148060532","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}

{"title":"Numerical investigation of streamwise vortex-induced vibration of a rotating cylinder subjected to an oscillatory flow","authors":"Muhammad Kashif,&nbsp;Adnan Munir,&nbsp;Ubaid Ur Rehman,&nbsp;Muhammad Hamza Ali,&nbsp;Ming Zhao,&nbsp;Heath Palmer,&nbsp;Mohammad S. Islam,&nbsp;Hafiz Hamza Riaz","doi":"10.1007/s42241-026-0018-9","DOIUrl":"10.1007/s42241-026-0018-9","url":null,"abstract":"<div><p>Vortex induced vibrations of a rotating cylinder placed in an oscillatory flow are investigated using two-dimensional numerical simulations at a Reynolds number of 150. The cylinder was allowed to undergo undamped vibrations only in the streamwise direction, with a constant mass ratio of <i>m*</i> = 2 and a range of reduced velocities from <i>V</i>_<i>r</i> = 1 to <i>V</i>_<i>r</i> = 20. Simulations were carried out for two Keulegan-Carpenter numbers of <i>Kc</i> = 5 and <i>Kc</i> = 10, with the non-dimensional rotation rate of the cylinder varying from <i>α</i> = 0 to <i>α</i> = 1. With an increase in <i>V</i>_<i>r</i>, the vibrational amplitude initially increased to reach a peak value in the lock-in range, beyond which it decreased. The rotation led to a higher peak value of the vibrational amplitude and this phenomenon was more prominent at <i>Kc</i> = 10. For both <i>Kc</i> = 5, 10, rotation rates greater than <i>α</i> = 0.5, 0.7, respectively, caused a secondary increase in the vibrational amplitude as <i>V</i>_<i>r</i> increased beyond the lock-in range. The fast Fourier transform analyses of the in-line force coefficient, and the in-line velocity were performed to highlight the influence of rotation on vibration frequencies and shedding patterns. The vortex shedding patterns showed that the wake flow patterns differ from the typical flow regimes observed for a non-rotating and non-vibrating cylinder. The effective Keulegan-Carpenter number, based on the relative velocity of the oscillatory flow and the vibrating cylinder, did not play a significant role in the formation of different flow regimes, and the transition between the regimes was found to be very irregular.</p></div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"38 1","pages":"154 - 169"},"PeriodicalIF":3.5,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148060883","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}

{"title":"Influence of wave-generation approach and structure position relative to extreme-wave event on wave dynamics and wave-induced loads","authors":"Robinson Perić,&nbsp;Jannes Berndt,&nbsp;Moustafa Abdel-Maksoud","doi":"10.1007/s42241-026-0017-x","DOIUrl":"10.1007/s42241-026-0017-x","url":null,"abstract":"<div><p>Three different approaches to generate long-crested extreme waves near the onset of breaking are investigated: Stokes 5th-order wave theory, linear focusing based on the NewWave theory and nonlinear focusing via Peregrine-breather-type rogue waves. The aims of this work are to compare the extreme-wave dynamics and to investigate the influence of structure placement on the maximum horizontal forces. An efficient simulation approach based on the finite-volume method was proposed for these investigations. Fixed vertical cylinders with diameters of 5% to 20% of the wavelength were subjected to the waves. The present results show that extreme-wave dynamics varied considerably. Wave breaking started at ca. 60% (linear focusing) and ca. 72% (rogue wave) of theoretical maximum steepness for a regular wave. For same wave height and steepness, linear focusing or rogue wave had up to ca. 14% larger maximum crest height <i>H</i>_c,max compared with the Stokes waves. For similar wave steepness, the Stokes wave gave the smallest horizontal forces, whereas whether linear focusing or rogue wave would give the largest forces depended on the severity of wave breaking. The main finding of this work is that the maximum horizontal force did not occur when the structure was positioned at the location of maximum wave elevation, but instead for placements up to 0.6 wavelengths before and up to nearly 0.18 wavelengths after the location of maximum wave elevation. Changing the structure’s position relative to the extreme-wave event changes the maximum horizontal forces by up to ca. 50% (linear focusing) and 22.7% (rogue wave). The variation reduced with increasing structure dimensions, to still ca. 13.8% (linear focusing) and 11.4% (rogue wave) for the fixed vertical cylinder with diameter of 0.2 wavelengths. The results of this study show that, to correctly determine maximum wave-induced loads, investigations must be repeated for different structure placements relative to the extreme-wave event. The work provides recommendations for performing such investigations and outlines related topics for future research.</p></div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"38 1","pages":"112 - 134"},"PeriodicalIF":3.5,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148060636","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}

{"title":"Delineating in-canopy sluggish zone in floating vegetation flows based on genetic programming: A penetration depth prediction model","authors":"Hong-hua Liu,&nbsp;Yi-dan Ai,&nbsp;Wen-xin Huai","doi":"10.1007/s42241-026-0016-y","DOIUrl":"10.1007/s42241-026-0016-y","url":null,"abstract":"<div><p>The floating vegetation hydrodynamically divides the flow into an upper “in-canopy sluggish zone” with reduced momentum and a lower “bilaterally confined advective zone” with higher momentum. Accurately defining the vertical extent of the in-canopy sluggish zone (described by the penetration depth) is critical for assessing the ecological functions of floating vegetation. In this study, a genetic programming (GP) algorithm was employed to establish an explicit predictive model quantifying this boundary. The model indicates that the penetration depth is governed by the Froude number, the vegetation slenderness ratio, the relative vegetation height, and the blockage ratio. Aside from achieving high predictive accuracy, the derived model reveals the competitive mechanisms controlling the development of the in-canopy sluggish zone. The zone’s extent is not a monotonic function of single parameters but rather the outcome of the dynamic balance between shear-driven instability and drag-induced damping. Compared with existing models, the proposed model demonstrates significant advantages in both applicability and accuracy, thus providing an effective tool for the assessment of aquatic organisms’ habitats.</p></div>","PeriodicalId":637,"journal":{"name":"Journal of Hydrodynamics","volume":"38 1","pages":"212 - 217"},"PeriodicalIF":3.5,"publicationDate":"2026-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148061143","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}