Ideas on New Fluid Dynamic Theory Based on the Liutex Rigid Rotation Definition

In recent years, a novel decomposition of fluid motion has been proposed, which mathematically defines a type of fluid rigid rotation distinct from vorticity, termed the Liutex quantity. Since its introduction, Liutex has been successfully applied to describe fluid vortices and has emerged as an internationally recognized third-generation vortex identification method. This new motion decomposition undoubtedly leads to a revised description of rotational and deformational motions, thereby necessitating a new description of dynamics. Therefore, based on the Stokes assumption and the novel Liutex decomposition, this paper constructs a new constitutive equation and derives a new set of fluid dynamic equations. The research findings reveal two key insights: first, the new shear stress in the fluid is no longer symmetric; second, in addition to traditional forces such as body force, pressure, and viscous force, an additional force induced by Liutex-based rigid rotation is identified. Furthermore, the new dynamic framework encompasses traditional fluid dynamics, with the latter being a special case when Liutex equals the traditional vorticity. It is anticipated that the proposed equations will find significant applications in the study of fluid vortices and turbulence and will undoubtedly stimulate research interest in the field of fluid mechanics.