本研究の目的は, 乗用車やトラック車両などの空力抵抗をさらに低減するため, 壁に沿う乱流の摩擦抵抗や一般的な形状の物体周りの流れの制御に関する基礎理論を確立することである。壁乱流の摩擦抵抗低減に関しては, 一様吹出し・吸込み制御および進行波状壁面変形制御の実用化に向けて克服すべき様々な効果の影響を数値シミュレーションによって検証するとともに, 波長空間におけるモード解析を行った。また, 任意形状の物体に働く空力抵抗の低減のために, まず圧力抵抗, 摩擦抵抗やエネルギー散逸と流れ場の物理量との間の関係を数学的に定式化し, それに基づく制御手法を提案し, 円柱, 角柱, および任意形状物体周りの流れにおいて検証した。
The purpose of this research is to establish basic theory on the control of friction drag of wall turbulence and a flow around general object in order to further reduce aerodynamic drag of cars and trucks. Regarding the reduction of the friction drag of the wall turbulence, we verified the effect of various effects to overcome toward practical application of uniform blowing and suction and traveling wave-like wall deformation by numerical simulation, and also conducted mode analysis in wavelength space. In order to reduce the aerodynamic drag acting on an object of an arbitrary shape, we first mathematically derived the relationship between pressure drag, friction drag, energy dissipation and the physical quantities in the flow field. Subsequently, we proposed a control method based on the derived relationship and verified it in the flows around a circular cylinder, a square cylinder, and an arbitrarily shaped object.
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