Numerical Analysis of Viscoelastic Start-up Flow in Channels with a Tapered Contraction

Abstract

Start-up flow of viscoelastic fluid in two-dimensional channels with a four to one tapered contraction was numerically analyzed using the finite element method, and the transient behavior of viscoelastic flow was discussed. The Leonov model was applied to describe the rheological behavior of the fluid.In the flow through the tapered contraction, the velocity gradient in the flow direction, 9u/8x, along the center line became smaller than that in the flow through an abrupt contraction, and the maximum of the normal stress difference, TXX -Tyy, in the tapered contraction channel was also smaller than that of the flow in the abrupt contraction channel.The peak position of 8u/8x moved with time, and this phenomenon has not been observed in the numerical simulation of the start-up flow in the channel with the abrupt contraction.