旋回関数の定義と渦流の同定法への応用

Abstract

A method of identification of swirling motion, with swirl function defined in this paper, and its application are presented. Flow characteristic can be classified with eigenvalue of velocity gradient tensor, and complex eigenvalue indicates that flow is swirling motion. Here the imaginary part of the complex eigenvalue is defined as swirl function, and the local maximum point of swirling function is assumed to be the axis of swirling motion. The swirl function can be considered as a physical property which corresponds to angular velocity of swirling, which is invariant in transformation of coordinate. This method enables to identify the swirling motion hidden in complicated flow, which is difficult to identify with velocity field or streamline, and also estimate the intensity of swirling.