Dilute Non-Newtonian Particle Suspension Rheology And Microstructure
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The study of polymeric particle suspensions has been the subject of a number of past experimental and theoretical studies. However, fundamental questions about suspension rheology and shear ﬂow-induced microstructural eﬀects remain. First, a quasi-analytical study is presented that gives the ﬁrst theory-based predictions on the eﬀects of ﬁnite polymer relaxation time on rheological properties. In a constant viscosity, low polymer concentration ﬂuid, the addition of particles is found to have a strong shear thickening eﬀect on the ﬁrst normal stress diﬀerence coeﬃcient and the shear viscosity. In contrast, the second normal stress diﬀerence coeﬃcient is shear thickening at low shear but shear thinning at higher shear. Next, an analytical and computational study is presented that sheds light on the widely studied phenomenon of cross-streamline particle migration in Poiseuille ﬂow. Particles are found to experience a cross-stream force toward the channel center when they are freely suspended in the ﬂuid, while they experience a crossstream force toward the wall when they are ﬁxed in place.
dissertation or thesis