Development of a numerical tool to deal with complex fluid/structure interactions: applications in energy efficiency, biomechanics and marine propulsion

本研究计划的长期目标是开发一种新的数值CFD（计算流体动力学）工具来研究涉及流体/结构相互作用的复杂流动系统。然后将其应用于能源效率、生物力学和船舶推进领域的四个具体情况。在各种情况下，人们可能会发现一个固体在叠加的流体流动中运动。固体运动可以是规定的（“单向耦合”）或由流体流动引起的（“双向耦合”）。*** 2014年，开始开发基于点阵玻尔兹曼方法的内部数值工具，并与考虑实体运动的浸入边界法耦合。这种耦合方法有许多优点：不需要自适应网格，即使在壁面上也能保持空间数值格式的准确性，通过改变粘度和/或在玻尔兹曼方程中加入外力，可以很容易地引入新的物理效应。该代码的当前版本能够模拟流动配置，包括在密度略有不同的两相分层流体介质中具有强加运动的固体和任意（非）润湿条件。***在接下来的五年里，我的研究计划将集中在CFD工具的数值发展上，以模拟更真实的流动形态，包括：非牛顿流体、湍流、流体/结构相互作用的“双向耦合”、孔隙弹性壁和磁场的影响。这种新的CFD工具将应用于机械工程的三个战略研究领域：***1/用于优化两种制冷系统的能效：用于磁力制冷的多孔蓄热器和用于冰浆的系统发生器/储罐。****2/在生物力学研究支气管粘液在人体呼吸系统的运输通过纤毛在上皮表面的同步跳动。****3/在船舶推进中使用弗莱特纳转子。这些高旋转气缸利用马格努斯效应诱导流向功率，使船舶推进所需的总能量节省约25%。***该代码将是第一个允许在如此复杂的情况下模拟流体/结构相互作用，同时保持结果在移动壁上的准确性的代码。除了该计划涵盖的四个应用之外，这个独特的工具将为许多其他应用打开大门：水和风力涡轮机的几何优化，海洋动物的纤毛运动推进和红细胞的运输等等。六名高素质的人员不仅在数字开发中隐含，而且在合作伙伴开发的实际应用中隐含，将在计划期间接受培训

The long-term objective of this research program is to develop a new numerical CFD (Computational Fluid Dynamics) tool to investigate complex flow systems involving fluid/structure interactions. It will be then applied to four concrete situations in the fields of energy efficiency, biomechanics and marine propulsion.***In various situations, one may find a solid body moving in a superimposed fluid flow. The solid body motion may be prescribed (« one-way coupling ») or induced by the fluid flow (« two-way coupling »).***In 2014, the development of an in-house numerical tool based on the Lattice Boltzmann method and coupled to an immersed boundary method to take into account the solid body motion has been initiated. This kind of coupled approach has many advantages: adaptative mesh grids are not required, the accuracy of the spatial numerical schemes is preserved even at the walls and the introduction of new physical effects is achieved easily by changing viscosity and/or by adding external body forces in the Boltzmann equation. The present version of the code enables to simulate flow configurations including a solid body with an imposed motion in a two-phase stratified fluid medium with slightly different densities and for arbitrary (de)wetting conditions.***In the next five years, my research program will focus on numerical developments of the CFD tool to simulate more realistic flow configurations, including: non-Newtonian fluids, turbulence, "two-way coupling" for the fluid/structure interaction, poro-elastic walls and effect of a magnetic field. This new CFD tool will be applied to three strategic research fields in mechanical engineering:***1/ in energy efficiency for the optimization of two refrigeration systems: a porous regenerator used in magnetic refrigeration and a system generator/storage tank for ice slurries.****2/ in biomechanics to study the transport of bronchial mucus in the human respiratory system by the synchronyzed beating of cilia at the epithelium surface.****3/ in marine propulsion by the use of Flettner rotors. These are high rotating cylinders using the Magnus effect to induce a streamwise power enabling to save about 25% of the total energy required for ship propulsion.***This code will be the first to allow the simulation of the fluid/structure interactions in such complex situations while preserving the accuracy of the results on the moving walls. In addition to the four applications covered by the program, this unique tool will open the door with many other applications: the geometrical optimization of water and wind turbines, the propulsion by ciliary motion of marine animals and the transport of the red cells among other things. Six highly qualified personnel implied not only in the numerical developments but also in the real applications developed at the partners, will be trained during the program.***