Chinyoka Tiri
Center for Research in Computational and Applied Mechanics, University of Cape Town, Rondebosch, 7701 South Africa.
Int J Appl Comput Math. 2021;7(3):75. doi: 10.1007/s40819-021-01023-4. Epub 2021 Apr 24.
A comparative computational study of the thermal response of Newtonian and non-Newtonian fluids subjected to exothermic reactions is conducted in simple shear flow. The investigations conducted in this study are of fundamental importance to industrial and biological applications in which heat generation minimization is important, such as in heat exchangers, in lubrication, and in internal medicine. Specifically, the comparative investigations central to this study are conducted on four types of fluids, namely; Newtonian fluids, generalized Newtonian fluids, viscoelastic fluids, and generalized viscoelastic fluids. The Oldroyd-B constitutive model is used for the viscoelastic fluids and a Carreau viscosity constitutive model is used to describe the viscosity shear-rate dependence of the generalized fluids. Efficient semi-implicit finite difference methods are employed to obtain the numerical solutions to the governing systems of equations. The computational methodologies are implemented in the MATLAB software. The sensitivity of the fluid temperature and the polymer stresses to increases in shear-thinning characteristics as well as to increases in polymeric properties is investigated. In general, it is observed that, at comparative parameter values, the viscoelastic fluids give the best resistance to temperature increases, followed by the generalized viscoelastic fluids, followed in turn by the Newtonian fluids, and with the generalized Newtonian fluids recording the highest temperature increases.
在简单剪切流中对经历放热反应的牛顿流体和非牛顿流体的热响应进行了一项对比计算研究。本研究中进行的调查对于工业和生物应用具有至关重要的意义，在这些应用中，将热量产生最小化很重要，例如在热交换器、润滑以及内科医学中。具体而言，本研究的核心对比调查是针对四种类型的流体进行的，即：牛顿流体、广义牛顿流体、粘弹性流体和广义粘弹性流体。对于粘弹性流体使用Oldroyd - B本构模型，对于广义流体使用Carreau粘度本构模型来描述粘度与剪切速率的依赖关系。采用高效的半隐式有限差分方法来获得控制方程组的数值解。计算方法在MATLAB软件中实现。研究了流体温度和聚合物应力对剪切变稀特性增加以及聚合物性能增加的敏感性。总体而言，可以观察到，在比较参数值时，粘弹性流体对温度升高的抵抗能力最佳，其次是广义粘弹性流体，接着是牛顿流体，而广义牛顿流体记录的温度升高最高。
