关键词: 直接数值模拟, 微尺度旋转圆柱, 剪切流动, 动量输运、流场分布

Abstract: Taking on the shear flow around a micro-sized rotating cylinder with ultra-high rotational speed as the subject, this study had employed Direct Numerical Simulation (DNS) to investigate the flow mechanism of microscale rotating cylinder shear flow. A microscale rotating cylinder shear flow model and numerical analysis method are established, reflecting the effects of large curvature and high velocity gradients. The physical mechanism of microscale rotating cylinder shear flow is revealed. Under the influence of high-speed microscale rotating cylinders inducing large curvature and high velocity gradients, the shear flow near the microscale rotating cylinder is in a weakly stable state. The tangential velocity and temperature decrease monotonically along the cylinder wall, while the turbulent kinetic energy first increases and then decreases radially, with a peak located at R/R0=2.5. In the near-wall region (R/R0=0.04), the amplitude of velocity and temperature responses is large, whereas in the far-field region (R/R0=0.38), the response amplitude is small and exhibits hysteresis. The instability induced by the microscale rotating cylinder is mainly located in the near-wall shear layer region, confirming significant differences in the attenuation patterns of velocity, turbulent kinetic energy, and temperature along the radial direction. The correlation between energy and momentum transport, rotational speed, and cylinder radius under microscale rotating cylinder shear flow is established. Velocity, temperature, and turbulent kinetic energy are approximately linearly positively correlated with rotational speed and cylinder radius. The former determines the intensity of energy and momentum transport through the coherent effects of viscous dissipation heat and convective heat transfer, while the latter enhances energy and momentum transport by strengthening viscous dissipation and altering curvature effects. This provides theoretical basis and technical support for the design of microscale rotating machinery equipment.

Key words: direct numerical simulation, rotated micro-scale cylinder, shear flow, momentum transport,, flow field distribution