Confluence of flow past an array of circular cylinders and its transition to turbulence.

流经一系列圆柱体的汇合及其转变为湍流。

• 批准号: 14540383
• 负责人: MIZUSHIMA Jiro
• 金额: $ 1.92万
• 依托单位: Doshisha University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540383/
• 关键词: array of circular cylinders; confluence of wakes; stability of flow; transition to turbulence; bifurcation; pitchfork bifurcation; Hopf bifurcation; two circular cylinders; 流れの不安定性

Interactions of wakes in a flow past a row of square or circular bars are investigated theoretically, numerically and experimentally. At small Reynolds numbers the flow is steady and symmetric with respect not only to stream-wise lines through the center of each bar but also to stream-wise centerlines between adjacent bars. However, the steady symmetric flow becomes unstable at larger Reynolds numbers and makes a transition to a steady asymmetric flow with respect to the centerlines between adjacent bars in some cases or to an oscillatory flow in other cases. It is found that vortices are shed synchronously from adjacent bars in the same phase or in anti-phase depending upon the distance between the bars when the flow is oscillatory. The origin of the transition to the steady asymmetric flow is identified as a pitchfork bifurcation, while the oscillatory flows with synchronous shedding of vortices are clarified to originate from a Hopf bifurcation. The critical Reynolds numbers of the … More transitions are evaluated numerically and the bifurcation diagram of the flow is obtained. These new findings were published in an article in Fluid Dynamics Research in 2002. In 2003 and 2004, the instability and transition of flow past two circular cylinders arranged in tandem are investigated numerically. We obtained the symmetric flow numerically and analyzed its stability by applying the linear stability theory. The nonlinear oscillatory flow arising from the instability was obtained not only by numerical simulation but also by direct numerical calculation of the equilibrium solution, and the bifurcation diagram for the nonlinear equilibrium solution is depicted. The transition of the flow from a steady state to an oscillatory state is clarified to occur due to a supercritical or sub-critical Hopf bifurcation depending upon the gap spacing. We found that there is a certain range of the gap spacing where physical quantities such as the drag and lift coefficients and the Strouhal number show an abrupt change when the gap spacing is continuously changed. We identified the origin of the abrupt change as the existence of multiple stable solutions for the flow. The paper including these results is published in the Physics of Fluids in 2005. Less

本文从理论上、数值上和实验上研究了流过一排方形或圆形棒材时尾迹的相互作用。在小雷诺数下，流动是稳定和对称的，不仅通过每个杆中心的流向线，而且相邻杆之间的流向中心线也是如此。然而，定常对称流在较大雷诺数时变得不稳定，并在某些情况下相对于相邻杆之间的中心线过渡到定常不对称流，或在其他情况下过渡到振荡流。研究发现，在振荡流动中，旋涡从同相或反相的相邻棒材上同步脱落，这取决于棒材之间的距离。确定了向稳定非对称流动过渡的起源为干草叉分岔，而具有同步脱落涡的振荡流动起源于Hopf分岔。通过数值计算得到了流动的临界雷诺数，得到了流动的分岔图。这些新发现发表在2002年《流体动力学研究》的一篇文章中。2003年和2004年分别对串联两圆柱流动的不稳定性和过渡进行了数值研究。对对称流进行了数值模拟，并应用线性稳定性理论分析了对称流的稳定性。通过数值模拟和对平衡解的直接数值计算，得到了不稳定引起的非线性振荡流动，并给出了非线性平衡解的分岔图。流动从稳态到振荡状态的转变澄清了由于依赖于间隙间距的超临界或亚临界霍普夫分岔而发生。我们发现，在一定的间隙间距范围内，当间隙间距连续变化时，阻力系数、升力系数和Strouhal数等物理量会发生突变。我们确定了突变的起源是流的多个稳定解的存在。包括这些结果的论文发表在2005年的《流体物理学》上。少

项目成果

柳崎淳: "矩形容器内の熱と物質の二重拡散対流"同志社大学理工学研究報告. 43. 125-134 (2002)

Jun Yanagisaki：“矩形容器内的热和物质的双重扩散对流”同志社大学理工学研究报告书43. 125-134 (2002)。

矩形容器内の熱と物質の二重拡散対流

矩形容器内热量和物质的双重扩散对流

• 发表时间: 2002
• 期刊: 同志社大学理工学研究報告 43
• 作者: 横山直人;水島二郎;Takeshi Akinaga;秋永 剛;横山 直人;Jiro Mizushima;水島 二郎;Takeshi Akinaga;横山直人;和田章弘;水島二郎;田中大介;Jiro Mizushima;水島二郎;Jiro Mizushima;芳松克則;Katsunori Yoshimatsu;Jiro Mizushima;Jiro Mizushima;Jiro Mizushima;柳崎淳
• 通讯作者: 柳崎淳

理工学のための数値計算法

科学与工程数值计算方法

• 发表时间: 2019
• 作者: 水島 二郎;柳瀬眞一郎;石原 卓
• 通讯作者: 石原 卓

平行2円板間放射状流れの不安定性と乱流への遷移

两个平行圆盘之间径向流动的不稳定性以及向湍流的转变

• 发表时间: 2003
• 期刊: 航空宇宙技術研究所特別資料 SP-59 59
• 作者: 横山直人;水島二郎;Takeshi Akinaga;秋永 剛;横山 直人;Jiro Mizushima;水島 二郎;Takeshi Akinaga;横山直人;和田章弘;水島二郎;田中大介;Jiro Mizushima;水島二郎;Jiro Mizushima;芳松克則
• 通讯作者: 芳松克則

流れの安定性

流量稳定性

• 发表时间: 2003
• 作者: 横山直人;水島二郎;Takeshi Akinaga;秋永 剛;横山 直人;Jiro Mizushima;水島 二郎;Takeshi Akinaga;横山直人;和田章弘;水島二郎;田中大介;Jiro Mizushima;水島二郎;Jiro Mizushima;芳松克則;Katsunori Yoshimatsu;Jiro Mizushima;Jiro Mizushima;Jiro Mizushima;柳崎淳;水島二郎
• 通讯作者: 水島二郎