Fluid dynamics and efficiency of colonial swimming via multijet propulsion at intermediate Reynolds numbers
Fluid dynamics and efficiency of colonial swimming via multijet propulsion at intermediate Reynolds numbers
复制标题
DOI：
10.1103/physrevfluids.6.013103
复制
发表时间：
2021-01-22
影响因子：
2.7
通讯作者：
Colin, Sean P.
中科院分区：
文献类型：
--
作者：
Jiang, Houshuo;Costello, John H.;Colin, Sean P.
殖民physonect管水母游泳通过横向分布的多射流推进在中间雷诺数（Re的）的订单1-1000。在这里，一个计算流体动力学的方法，假设稳定的轴对称流调查的基本流体力学和适应值的殖民游泳通过横向分布的多喷口推进，与后方喷射单喷口推进相比。结果表明，施加的流场，阻力系数，功率和效率都显着变化取决于雷诺数，射流角度，和喷射方式。对于给定的Re，确定了两种类型的最佳喷流角：一种在61度-70度的范围内，使准推进效率最大化（即，以最小化喷气动力），以及另一个在34度-45度的范围内以最大化弗劳德推进效率（即，以使尾流最小化）。与记录的管水母，Nanomia bijuga值的比较表明，管水母依赖于这两个理论最优之间的喷射角度的频谱。多个，横向定向射流产生的殖民形式是较少的能量效率比单一的，后定向射流产生的孤独的个人推进，然而，殖民游泳实现了精力充沛的好处，为个人喷射内的殖民地，因为他们需要显着降低每模块的功率比所需的一个单独的喷气模块以相同的速度游泳。因此，通过分担推进职责，群体的形成有助于减轻刺胞动物肌肉固有的力量限制。重要的是，被引导成倾斜地远离中心体轴线的多个射流对在喷射聚集的尾流中被拖曳的虹吸体内的其他集落成员施加较小的影响。
Colonial physonect siphonophores swim via laterally distributed multijet propulsion at intermediate Reynolds numbers (Re's) on the orders of 1-1000. Here, a computational fluid dynamics approach that assumes steady axisymmetric flow is employed to investigate the underlying fluid mechanics and adaptive values of colonial swimming via laterally distributed multijet propulsion, with comparison with rear jetting single-jet propulsion. Results show that imposed flow fields, drag coefficients, powers, and efficiencies all vary significantly depending upon Re, jet angle, and way of jetting. For a given Re, two types of optimal jet angles are determined: one in the range of 61 degrees-70 degrees that maximizes the quasipropulsive efficiency (i.e., to minimize the jet power), and another in the range of 34 degrees-45 degrees that maximizes the Froude propulsion efficiency (i.e., to minimize the wake). Comparison with values for a documented siphonophore, Nanomia bijuga, indicates that siphonophores rely upon a spectrum of jet angles between these two theoretical optima. Multiple, laterally directed jets produced by colonial forms are less energetically efficient for propulsion than single, posteriorly directed jets produced by solitary individuals; however, colonial swimming achieves energetic benefits for jetting individuals within the colony because they require significantly lower per-module power than that required by a lone jet module swimming at the same speed. Hence, by sharing propulsive duties, colony formation helps alleviate inherent power constraints that characterize cnidarian muscles. Importantly, multiple jets that are directed obliquely away from the central body axis exert less impact on other colony members within the siphosome that is towed in the wake of the jetting aggregation.