Numerical simulations can help to clarify details of the complex flow processes in fresh concrete and thus deepen our understanding of its rheology. For this purpose, the “Numerics” working group in SPP 2005 is developing numerical models that describe the movements of both individual particles and fluid phases as well as their interactions. Benchmark studies and round robin tests are used to check that these models are of high quality. They shall be used for the ongoing research within the priority program of the German Research Foundation (DFG SPP 2005).
Working Group Numerics in SPP 2005 develops numerical models which capture the dynamics of the granular and fluid phases in fresh concrete. Simulations with these models are used to research details of fresh concrete flows. In detail, WG Numerics has the following goals:
Haustein, M. A., Zhang, G., Schwarze, R., Segregation of granular materials in a pulsating pumping regime, Granular Matter, 2019
Secrieru, E., Mohamed, W., Fataei, S., Mechtcherine, V., Assessment and prediction of concrete flow and pumping pressure in pipeline, Cement and Concrete Composites, 2020
A major achievement of the working group resulted in a paper, which presented the results of an interlaboratory study of the rheological properties of cement paste and ultrasound gel as reference substance. The goal was to quantify the comparability and reproducibility of measurements of the Bingham parameters yield stress and plastic viscosity when measured on one specific paste composition and one particular ultrasound gel in different laboratories using different rheometers and measurement geometries. The procedures for both in preparing the cement paste and carrying out the rheological measurements on cement paste and ultrasound gel were carefully defined for all of the study’s participants. Different conversion schemes for comparing the results obtained with the different measurement setups are presented here and critically discussed. The procedure proposed in this paper ensured a reasonable comparability of the results with a coefficient of variation for the yield stress of 27% and for the plastic viscosity of 24%, despite the individual measurement series’ having been performed in different labs with different rheometers and measurement geometries.
CFD-Benchmark: Comparison of different software packages for a velocity profile of a non-Newtonian fluid after a pipe-bend.
DEM-Benchmark: Development of integrated potential and kinetic energy of all particles in a slump flow.