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Accurate constitutive equations are required for the understanding of many food processes. The purpose of this work was to test the ability of constitutive equations to model the rheological behavior of β-glucan/amylodextrin blends in a range of flows. The predictions of the K-BKZ, Giesekus, Phan-Thien–Tanner and Bird–Carreau models were compared to experimental results in steady shear, startup of steady shear, stress relaxation and biaxial extension flows. The K-BKZ model yielded the most accurate predictions across the range of flows. The Giesekus and Phan-Thien–Tanner models gave good results in shear flows, but failed to predict the correct strain dependence in stress relaxation. The Bird–Carreau model did not capture many features of the flow behavior. The results indicate the need to test thoroughly constitutive equations before using them to model food processes. |
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