Fiber orientation distribution and rheological properties of fiber suspension in a turbulent jet

Abstract

The fiber orientation distribution and rheological properties of fiber suspension in a turbulent jet are numerically studied. The results show that, as the flow develops, more fibers align themselves with the flow direction. Few fibers orient with the flow direction with the increase of the fiber volume fraction and the Reynolds numbers. The fibers with large aspect ratio tend much easier to align with the flow direction, and the fiber orientation distribution is not sensitive to the aspect ratio when it is larger than 5. The shear stress increases along the flow direction and decreases from the center to the outside. The addition of fibers makes an increase of the shear stress, and the magnitude of increase is directly proportional to the fiber volume fraction, Reynolds number and fiber aspect ratio. The first normal stress difference is much less than the shear stress, and increases along the flow direction and from the center to the outside. It increases with increasing the fiber volume fraction and aspect ratio, and decreasing Reynolds number. The differences in the shear stress and the first normal stress difference for different parameters are the most and the least obvious at the centerline and the outside, respectively.