A study of viscoelastic flow problems around bodies associated with the change of type of the governing system of equations

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04164
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: Chiba University
• Principal Investigator: Mikami Fumihiko 千葉大学, 大学院工学研究院, 准教授 (40272348)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 流体力学 / 粘弾性流体 / 型変化 / 数値シミュレーション / 可視化 / 粘弾性マッハ数 / デボラ数

Outline of Final Research Achievements

In a uniform viscoelastic fluid flow, shear waves or vorticity waves are generated on the body surface. The radius of the propagating wavefront depends only on the viscoelastic Mach number and determines the type of the governing equations. In contrast, the Deborah number determines the radial profile of vorticity that can be classified into two different types depending on the Deborah numbers. One is the diffusion-type transport when the Deborah number is relatively small, and the other is the traveling wave-type transport when the Deborah number is relatively high. The flow is affected by the Deborah number effect as well as by the consequence of a change of type of governing equations. We also find that the tensile forces in the fluid play an important role in the flow at a considerably high Deborah number.

Free Research Field

流体力学

Academic Significance and Societal Importance of the Research Achievements

Josephら（1985）が提唱した物体まわりの粘弾性流体の流れの空気力学的描像では粘弾性マッハ数のみがパラメータに使われているのに対して，本研究で提唱するモデルでは，粘弾性マッハ数とデボラ数の２つのパラメータを使用しており，実際の流れ場をより的確に表すことができる．デボラ数がかなり大きい流れでは，張力が流体に貼り付いて運動する様子が見られたことから，磁気流体力学的な描像も重要になってくることが示唆される．