Joye Donald D
Department of Chemical Engineering, Villanova University, Villanova, PA 19085-1681, USA.
J Colloid Interface Sci. 2003 Nov 1;267(1):204-10. doi: 10.1016/j.jcis.2003.07.035.
Shear rate and viscosity correction factors for a Casson fluid in cylindrical (Couette) geometries--type I, concentric cylinder with a narrow gap, and type II, cylinder in a semi-infinite medium--are developed in this work. The analytical correction factors compare well with published data corrected by general methods. Corrected viscosities were also compared to viscosity-shear rate data on chocolate in an absolute viscometer (cone-and-plate), which requires no corrections. This comparison showed excellent agreement of the corrected data in the higher shear rate range, but not very good agreement in the lower shear rate range. Reasons for this are discussed. In addition, a Reiner-Riwlin type formulation was developed for determination of model constants directly from rotational viscometry data without the need to correct for non-Newtonian shear rate, but this method is less accurate than existing slope-intercept methods for determining model constants. The analytical correction procedure developed here is expected to be useful wherever the Casson model is used to describe the rheology of a fluid, particularly one exhibiting yield-stress pseudoplastic behavior.
本文推导了圆柱（库埃特）几何形状中卡森流体的剪切速率和粘度校正因子——I型为具有窄间隙的同心圆柱，II型为半无限介质中的圆柱。分析得到的校正因子与用常规方法校正的已发表数据吻合良好。还将校正后的粘度与绝对粘度计（锥板）中巧克力的粘度-剪切速率数据进行了比较，该粘度计无需校正。这种比较表明，校正后的数据在较高剪切速率范围内吻合良好，但在较低剪切速率范围内吻合不太好。文中讨论了其原因。此外，还开发了一种赖纳-里夫林型公式，可直接从旋转粘度测量数据中确定模型常数，而无需对非牛顿剪切速率进行校正，但该方法在确定模型常数方面不如现有的斜率-截距法准确。预计本文开发的分析校正程序在使用卡森模型描述流体流变学的任何地方都将有用，特别是对于表现出屈服应力假塑性行为的流体。
