Determining true material constants of viscoplastic materials from rotational rheometer data
Date
2018Author
Alexandrou, Andreas N.Georgiou, Georgios C.
Economides, Eva-Athena
Zang, Christoph
Modigell, Michael
ISSN
0377-0257Source
Journal of Non-Newtonian Fluid MechanicsVolume
260Pages
101-108Google Scholar check
Metadata
Show full item recordAbstract
We analyse the circular Couette flow of Herschel–Bulkley fluids to investigate the validity of the assumption that the rate of strain distributions across the gap share a common point. It is demonstrated that this is true only with fully-yielded Bingham -plastic flow. In other cases, e.g., in partially-yielded Bingham-plastic flow or fully-yielded Herschel–Bulkley flow, the common point for the fully-yielded Bingham case provides a good approximation for determining material constants only if the gap is sufficiently small. We also revisit the important issue of determining material properties of viscoplastic fluids by using “true values” for the rate of strain and demonstrate that the material properties can be very different from those obtained using “apparent’ values for the rate of strain.