A NUMERICAL-SOLUTION FOR THE FLOW OF DILUTE FIBER SUSPENSIONS THROUGH AN AXISYMMETRIC CONTRACTION

Finite difference numerical solutions are presented for the flow of dilute suspensions of rigid, high aspect-ratio fibers in Newtonian fluids flowing in an axisymmetric circular 4 to 1 contraction. A continuum theory developed by Lipscomb et al. is used to describe the flow properties of the suspensions. The numerical results in terms of the size and shape of the secondary flow vortex are in agreement with the finite element predictions of Lipscomb et al. and the flow visualization experiments of Hur. The work confirms and extends the results presented by Lipscomb et al. and clearly shows how the presence of fiber, even at very low concentration, drastically changes the kinematics of tubular entry flows. Fiber orientation in tubular entry flows cannot be computed by assuming the flow kinematics are independent of the presence of fibers, even in the limit of very low concentrations. © 1990.