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Erschienen in:
2020 | OriginalPaper | Buchkapitel
Numerical Simulation of the Flow Behavior of Newtonian Fluids in a Wide Gap Rheometer by CFD
verfasst von : Mahmoud Eslami Pirharati, Dimitri Ivanov, Hans-W. Krauss, Carsten Schilde, Dirk Lowke
Erschienen in: Rheology and Processing of Construction Materials
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Abstract
Wide gap coaxial rheometers with vane-in-cup systems are widely used to determine rheological properties of cement paste, mortar and concrete. Available analytical models allow the calculation of average shear stress with acceptable accuracy. However, they exhibit serious oversimplifications, e.g. torque contributions of other parts than the vertical cylinder equivalent surface or neglecting of stress peaks. Hence, the accuracy of calculated shear stress values may be questionable depending on the actual purpose.
In the present contribution, experimental investigations of Newtonian fluids in a wide gap rheometer with both, a coaxial smooth steel cylinders and a vane-in-cup system, are presented. Accuracy of analytical models is discussed with respect to shear rate distributions over gap and over cylinder resp. vane probe surfaces determined from Computational Fluid Dynamics (CFD) simulations. A modified analytical model is proposed. As will be shown, the averaged shear rates over one revolution calculated from CFD simulations are comparable with the modified analytical model. Further results are discussed and an outlook for future research is given.