In a recently published work (Sheng, 2020), Sheng identified inconsistencies in the concepts and principles leading to the Navier–Stokes equations and proposed a new asymmetric “friction tensor” to resolve these inconsistencies. We show that this friction tensor can be interpreted as the non-isotropic part of a vorticity-influenced viscous stress tensor following the analysis in Berdahl and Strang (1986). The asymmetric stress tensor however violates the principles of mechanical equilibrium in fluid flows that are free of external or body couples and is therefore non-physical in classical continuum hydrodynamics. We refute the arguments in favour of the asymmetric stress tensor in Sheng (2020) whilst also demonstrating that the friction tensor leads to the incorrect form of the Navier–Stokes equations in non-Cartesian co-ordinates and its ability to recover the correct governing equations in Cartesian co-ordinates is fortuitous.

在最近发表的工作中（Sheng，2020），Sheng指出了导致Navier–Stokes方程的概念和原理中的不一致之处，并提出了新的非对称“摩擦张量”来解决这些不一致之处。我们表明，根据Berdahl和Strang（1986）的分析，该摩擦张量可以解释为受涡度影响的粘性应力张量的非各向同性部分。然而，非对称应力张量违反了流体流中机械平衡的原理，该流体流没有外部或主体耦合，因此在经典连续流体力学中是非物理的。