Orientation distribution and rheological properties of fiber suspensions flowing through curved expansion and rotating ducts

Abstract

In dilute fiber suspensions, the Jeffery equation is employed to predict the fiber orientation distribution through a curved expansion and rotating duct. The results show that the fiber flips more quickly in the inlet region, especially in the region close to the concave wall. In the central region and the downstream region, the fiber orientation distributions are more uniform. In semi-dilute fiber suspension, the fiber interactions can be represented by a statistical model developed by Folgar & Tucker. Then a deduced Fokker-Planck equation can be used to describe the fiber orientation distribution probability. In the present work, the Fokker-Planck equation is directly solved by FVM. Then with the probability, the fiber orientation tensors are obtained. Furthermore, the fiber extra stresses are gained with the Batchelor model. The results show that the shear stress and normal stress difference are concentrated around the inlet close to the concave wall regions. In the central regions, these properties are less obvious. And in the downstream, these properties are negligible.