Development of Hybrid Wind Tunnel Through Integration of Supercomputer and Experimental Wind Tunnel

本研究旨在建立一种新的复杂流动问题的分析方法。将数值风洞与实验风洞相结合，研制了“混合风洞”。首先，构建了实验风洞，并通过千兆以太网与东北大学流体科学研究所的超级计算机系统连接。本文研究了均匀流场中方柱尾流中卡门涡街的基本流场。将塔侧壁上的压力信号反馈到实时计算以减小估计误差。经过一段过渡后，流场的计算结果收敛于真实的流动。通过数值仿真优化了反馈律，并通过实验验证了反馈律的有效性.通过对方柱两侧压力的测量，计算结果很好地收敛于包含主流初始扰动影响的真实的非定常流。真实的实时计算在混合风洞中是必不可少的，并通过并行计算进行了探索。作为混合风洞的可能应用，还研究了活体血液流动控制和通过反馈控制减小飞行器的气动阻力。

This research project aims to establish a new analysis methodology to complex flow problems. Through integration of numerical wind tunnel and experimental wind tunnel, a "Hybrid Wind Tunnel" was developed. First, an experimental wind tunnel was constructed and was connected to the supercomputer system of the Institute of Fluid Science, Tohoku University through a Gigabit Ethernet. As a fundamental flow field, Karman Vortex Street in the wake of a square column in a uniform flow was investigated. A pressure signal on a side wall of the column is fed back to the real-time computation to reduce the estimation error. After some transient, the computational result for the flow field converges to the real flow. The feedback law was optimized through numerical simulation and confirmed by experiment. Using pressure measurement on both sides of the square column, the computational result well converges to the real unsteady flow including the effect of perturbations initially existent in the main flow. Real time computation is essential in the hybrid wind tunnel and is explored through parallel computing. Blood flow control in living bodies and aerodynamic drag reduction of vehicles by feedback control are also investigated as possible application of hybrid wind tunnel.