Nikushchenko Dmitry, Pavlovsky Valery, Nikushchenko Elena
Institute of Hydrodynamics and Control Processes, Saint-Petersburg State Marine Technical University, Lotsmanskaya 3, 190121 Saint-Petersburg, Russia.
Research Department, Saint-Petersburg State Marine Technical University, Lotsmanskaya 3, 190121 Saint-Petersburg, Russia.
Polymers (Basel). 2022 Aug 14;14(16):3308. doi: 10.3390/polym14163308.
In the presented article a generalization of Newton's formula for the shear stress in a fluid is carried out by giving it a power-law form. After the introduction of the corresponding strain rate tensor, a generalization is made to the spatial case of flow and the rheological relation is presented in tensor form. Depending on the power value in this rheological ratio, one can come either to a description of a laminar flow regime (in the form of Navier-Stokes equations), or to a description of the flow in turbulent regime. In the latter case, a set of differential equations with the no-slip boundary condition is specified, which is significantly different from that for the laminar flow regime, but which also allows one to obtain analytical solutions for simple shear flows and obtain the Blasius resistance law for the flow in a pipe. Therefore, the considered approach to solving problems of turbulent flows compares favorably with modern differential turbulence models. Solutions are given for simple shear flows of a fluid, when there is only one longitudinal component of the velocity, which depends on the transversal coordinate only. These solutions in terms of velocity profiles and resistance coefficients are in satisfactory agreement with the experimental data.
在本文中,通过赋予牛顿流体剪切应力公式幂律形式对其进行了推广。引入相应的应变率张量后,将其推广到空间流动情形,并以张量形式给出流变关系。根据该流变比中的幂值,既可以得到层流状态的描述(以纳维 - 斯托克斯方程的形式),也可以得到湍流状态的描述。在后一种情况下,给出了一组具有无滑移边界条件的微分方程,它与层流状态的方程有很大不同,但也能让我们得到简单剪切流的解析解,并得到管道流动的布拉修斯阻力定律。因此,所考虑的求解湍流问题的方法与现代微分湍流模型相比具有优势。给出了流体简单剪切流的解,此时速度只有一个纵向分量,且仅取决于横向坐标。这些关于速度剖面和阻力系数的解与实验数据吻合良好。