Viscometric functions of semi-dilute non-colloidal suspensions of spheres in a viscoelastic matrix

The main interest centres on the second normal stress difference N2. The matrix fluid showed a zero second normal stress difference, and the measurements showed that N2 was always negative for the suspensions. This agrees with the dilute suspension prediction found using the Landau-Lifschitz averaging procedure, but not with the ensemble averaging method, which predicts a positive N2. Possible causes for this result are discussed.