为了深入分析钢悬链线立管的振动特性,基于Van Der Pol尾流振子模型,该文研究了海洋钢悬链线立管在对数剪切外流和内流共同作用下的振动规律。结果表明:立管振动表现出驻波和行波组合的特性,随内流流速的增加,由驻波主导逐渐转化为行波...为了深入分析钢悬链线立管的振动特性,基于Van Der Pol尾流振子模型,该文研究了海洋钢悬链线立管在对数剪切外流和内流共同作用下的振动规律。结果表明:立管振动表现出驻波和行波组合的特性,随内流流速的增加,由驻波主导逐渐转化为行波主导。随来流剖面剪切程度增加,立管振动均方根位移的最大值逐渐减小。而随内流速度的增加,均方根位移的最大值变化与行波传播方向发生转变有关。立管的振动响应呈现出明显的多频特征,且随来流剪切程度的增加,立管振动主频不断升高。但相同的来流剖面下,随着内流流速的增加,振动位移的主导频率反而逐渐减小。立管的振动为多模态共同参与的结果,各模态之间存在竞争关系,振动过程中,振动模态存在空间上竞争与时间上切换的特征。研究结果对钢悬链线立管后期的疲劳预测具有重要的参考意义。展开更多
Droplet impact on solid surfaces plays a critical role in a wide range of applications,including inkjet printing,spray cooling,surface coatings,and microdroplet chemistry.Precise control of droplet–surface interactio...Droplet impact on solid surfaces plays a critical role in a wide range of applications,including inkjet printing,spray cooling,surface coatings,and microdroplet chemistry.Precise control of droplet–surface interactions is essential,but the fundamental mechanisms governing this process are still not fully understood.In this study,we demonstrate that large contact angle hysteresis(CAH)on hydrophobic nanoporous surfaces significantly amplifies post-impact droplet oscillations.This reveals the critical influence of CAH on the redistribution of impact energy and the modulation of droplet–surface interactions.Using shape mode decomposition via Legendre polynomials and fast Fourier transform spectral analysis,we show that surfaces with larger CAH excite and sustain higher-order droplet shape mode oscillations,leading to persistent capillary waves even after contact line pinning.The observed amplitude modulation and multiple frequency components within individual shape modes reveal nonlinear energy transfer between different modes.These amplified and coupled oscillations are shown to promote daughter droplet coalescence.This study presents a framework for understanding the role of CAH in storing and redistributing impact energy through nonlinear mode excitation and establishes CAH as a critical design parameter for controlling fluid dynamics on solid surfaces.展开更多
Droplet impact dynamics on solid surfaces,which are ubiquitously present in aerospace engineering,energy systems,agricultural production,etc.,involve complex fluid–structure interactions.Herein,we employ a single-cam...Droplet impact dynamics on solid surfaces,which are ubiquitously present in aerospace engineering,energy systems,agricultural production,etc.,involve complex fluid–structure interactions.Herein,we employ a single-camera high-speed threedimensional digital image correlation system to quantify the full-field deformations of flexible thin films during droplet impact dynamics.Experimental results revealed that the substrate flexibility not only reduces the maximum spreading diameter by 10%but also modulates rebound dynamics via energy competition between kinetic energy and surface adhesion energy,suggesting that coupled deformation of the solid–fluid interface plays an important role in the dynamic progress.We propose the structure-coupled response number(Sn),a governing dimensionless parameter unifying droplet spreading on both rigid and flexible films,validated by a universal 1/2 scaling law.A theoretical criterion for droplet rebound on hydrophobic flexible thin films is derived and experimentally demonstrated,which achieves the precise control of droplet rebound/non-rebound mode.This work bridges the theories of droplet impact dynamics on rigid and flexible substrates,offering a robust strategy to govern the droplet impact behaviors.展开更多
针对自由表面流动与弹性结构的流固耦合计算效率低、计算耗时长的问题,将流体体积法与基于结构-虚拟弹性体的快速动网格方法相结合,发展了一种适用于自由表面流动的高效流固耦合方法。使用流体体积(volume of fluid,VOF)法对流体自由表...针对自由表面流动与弹性结构的流固耦合计算效率低、计算耗时长的问题,将流体体积法与基于结构-虚拟弹性体的快速动网格方法相结合,发展了一种适用于自由表面流动的高效流固耦合方法。使用流体体积(volume of fluid,VOF)法对流体自由表面进行追踪;将流体域视为虚拟弹性体并构建结构-虚拟弹性体系统,以流固耦合界面的多相流体力为激励求解系统的动力学方程得到结构振动位移和流场网格变形;在每一个时间步内依次求解流体流动、结构变形和流场动网格,实现流固耦合计算。基于发展的方法计算了溃坝水流冲击下弹性挡板的流固耦合响应,得到了溃坝水流的自由液面和弹性挡板的运动行为,结果表明:自由液面演变和弹性挡板振动位移的计算结果与已有算法的结果吻合良好;在同等网格规模下,与已有算法相比本文方法可减少33.3%的计算时间;在水流冲击作用下,弹性挡板向冲击侧小幅弯曲。随后水流沿挡板左侧上升并形成射流,挡板向另一侧大幅弯曲。最后由于两侧流体的阻尼,挡板振幅逐渐衰减。展开更多
文摘为了深入分析钢悬链线立管的振动特性,基于Van Der Pol尾流振子模型,该文研究了海洋钢悬链线立管在对数剪切外流和内流共同作用下的振动规律。结果表明:立管振动表现出驻波和行波组合的特性,随内流流速的增加,由驻波主导逐渐转化为行波主导。随来流剖面剪切程度增加,立管振动均方根位移的最大值逐渐减小。而随内流速度的增加,均方根位移的最大值变化与行波传播方向发生转变有关。立管的振动响应呈现出明显的多频特征,且随来流剪切程度的增加,立管振动主频不断升高。但相同的来流剖面下,随着内流流速的增加,振动位移的主导频率反而逐渐减小。立管的振动为多模态共同参与的结果,各模态之间存在竞争关系,振动过程中,振动模态存在空间上竞争与时间上切换的特征。研究结果对钢悬链线立管后期的疲劳预测具有重要的参考意义。
基金supported by the German Federal Ministry of Education and Research(BMBF)within the project H2Giga-SINEWAVE OxySep,grant no 03HY123Eand the Faculty of Mechanical Science and Engineering at TU Dresden.Pengfei Zhao would like to acknowledge the China Scholarship Council(CSC)+3 种基金supported by a Humboldt Research Fellowship from the Alexander von Humboldt Foundationthe financial support from Qinghai Province(No.2025ZY001,2024000060)Chinese Academy of Sciences(No.2023000024)funding from the Deutsche Forschungsgemeinschaft:Project ID 265191195-SFB1194 and 456180046.
文摘Droplet impact on solid surfaces plays a critical role in a wide range of applications,including inkjet printing,spray cooling,surface coatings,and microdroplet chemistry.Precise control of droplet–surface interactions is essential,but the fundamental mechanisms governing this process are still not fully understood.In this study,we demonstrate that large contact angle hysteresis(CAH)on hydrophobic nanoporous surfaces significantly amplifies post-impact droplet oscillations.This reveals the critical influence of CAH on the redistribution of impact energy and the modulation of droplet–surface interactions.Using shape mode decomposition via Legendre polynomials and fast Fourier transform spectral analysis,we show that surfaces with larger CAH excite and sustain higher-order droplet shape mode oscillations,leading to persistent capillary waves even after contact line pinning.The observed amplitude modulation and multiple frequency components within individual shape modes reveal nonlinear energy transfer between different modes.These amplified and coupled oscillations are shown to promote daughter droplet coalescence.This study presents a framework for understanding the role of CAH in storing and redistributing impact energy through nonlinear mode excitation and establishes CAH as a critical design parameter for controlling fluid dynamics on solid surfaces.
基金supported by the National Key R&D Program of China(grant nos.2022YFF0503500 and 2022YFA1203200)the Guangdong Basic and Applied Basic Research Foundation(grant no.2023A1515011784)+2 种基金the National Natural Science Foundation of China(grant no.12032019)the Strategic Priority Research Program of Chinese Academy of Sciences(grant nos.XDB0620101 and XDB0620103)the Youth Innovation Promotion Association,Chinese Academy of Sciences(no.2020020).
文摘Droplet impact dynamics on solid surfaces,which are ubiquitously present in aerospace engineering,energy systems,agricultural production,etc.,involve complex fluid–structure interactions.Herein,we employ a single-camera high-speed threedimensional digital image correlation system to quantify the full-field deformations of flexible thin films during droplet impact dynamics.Experimental results revealed that the substrate flexibility not only reduces the maximum spreading diameter by 10%but also modulates rebound dynamics via energy competition between kinetic energy and surface adhesion energy,suggesting that coupled deformation of the solid–fluid interface plays an important role in the dynamic progress.We propose the structure-coupled response number(Sn),a governing dimensionless parameter unifying droplet spreading on both rigid and flexible films,validated by a universal 1/2 scaling law.A theoretical criterion for droplet rebound on hydrophobic flexible thin films is derived and experimentally demonstrated,which achieves the precise control of droplet rebound/non-rebound mode.This work bridges the theories of droplet impact dynamics on rigid and flexible substrates,offering a robust strategy to govern the droplet impact behaviors.
文摘针对自由表面流动与弹性结构的流固耦合计算效率低、计算耗时长的问题,将流体体积法与基于结构-虚拟弹性体的快速动网格方法相结合,发展了一种适用于自由表面流动的高效流固耦合方法。使用流体体积(volume of fluid,VOF)法对流体自由表面进行追踪;将流体域视为虚拟弹性体并构建结构-虚拟弹性体系统,以流固耦合界面的多相流体力为激励求解系统的动力学方程得到结构振动位移和流场网格变形;在每一个时间步内依次求解流体流动、结构变形和流场动网格,实现流固耦合计算。基于发展的方法计算了溃坝水流冲击下弹性挡板的流固耦合响应,得到了溃坝水流的自由液面和弹性挡板的运动行为,结果表明:自由液面演变和弹性挡板振动位移的计算结果与已有算法的结果吻合良好;在同等网格规模下,与已有算法相比本文方法可减少33.3%的计算时间;在水流冲击作用下,弹性挡板向冲击侧小幅弯曲。随后水流沿挡板左侧上升并形成射流,挡板向另一侧大幅弯曲。最后由于两侧流体的阻尼,挡板振幅逐渐衰减。
