Numerical simulation on the flow of a viscoelastic fluid through an axisymmetric abrupt contraction−Effect of elongational flow characteristics on vortex and entrance pressure drop (abstract)

Abstract

The flow of a viscoelastic fluid through a 4:1 axisymmetric abrupt contraction was studied by means of the finite element method. The effects of elongational viscosity on vortex and entrance pressure drop were investigated in detail using the viscoelastic models which have different values of elongational viscosity by varying the model parameters. The Phan Thien–Tanner (PTT) type and the Giesekus type models with a single relaxation time were used as the constitutive equations. It is found that the vortex grows with the recoverable strain and the model with higher elongational viscosity predicts a larger and more intensive vortex. It seems that the vortex becomes more intensive as recoverable strain becomes larger if elongational viscosity curves coincide. The model with higher elongational viscosity gives larger values for the entrance correction in the PTT type model, while the Giesekus type model gives the opposite prediction. It seems that the magnitude of entrance correction cannot be explained only from the elongational viscosity.