(87b) Variability of Sphere- and Tetrapod-Based DEM-Simulations for Poorly Flowing Materials

In the realm of chemical engineering applications, it is imperative to embrace innovative solutions like residue-derived fuels, battery recycling, and biomass utilization. It is clear, that approaches like these pave the way towards a more sustainable future. Thus, the modelling of such, rather poorly flowing, systems is of crucial importance. However, the respective primary particles are complex shaped and therefore not well suited as a basis for a useful DEM-simulation approach. This brings forth the concept of treating them as parcels [1]. In the current approach, tetrahedral multi-spheres with non-touching spheres (“tetrapods”) are used as a basic geometric concept for those parcels.

Our current work investigates the variability of predictions using a tetrapod approach [2], as well as using conventional spheres. We focus on a simple draw-down test, as shown in Figure 1, and study the effect of the filling procedure’s parameters on the models prediction [3]. Furthermore, the effect of using distributions for (i) the tetrapod properties and (ii) the force-parameters in the contact model are investigated in the spirit of O’Sullivan et al. [4]. Specifically, we are successful to describe fluctuations occurring naturally in our lab experiments (and in real world applications), which are due to the nonideality of such systems. Finally, the effect of parcel size (which is known to be non-trivial as shown by Tausendschön et al. [5]) is quantified, and an attempt is made to calibrate the DEM simulator also for correct prediction of the fluctuations seen in our experiments. Using our novel approach, systems with poorly flowing materials and strong nonidealities can be quantitatively described.

[1] S. Radl, C. Radeke, J. G. Khinast, and S. Sundaresan, “Parcel-Based Approach For The Simulation Of Gas-Particle Flows” 8th Interantional Conference on CFD in Oil & Gas, Metallurgical and Process Industries, no. June, 2011.

[2] S. Radl, H. Benabchiasli, G. Fasching, M. Mitterlindner, and M. Salehi, “How CFD-DEM Simulations benefit from Machine Learning”, Editorial to the Proceedings of 11th European Conference on Industrial Furnaces and Boilers, INFUB-14, 2-5 Apr. 2024.

[3] J. Leak and D. Barreto, “A DEM study on the effect of inherent variability of assemblies of spherical particles”, doi: 10.53243/NUMGE2023-388.

[4] C. O’Sullivan, J. D. Bray, and M. F. Riemer, “Influence of Particle Shape and Surface Friction Variability on Response of Rod-Shaped Particulate Media”, doi: 10.1061/ASCE0733-93992002128:111182.

[5] J. Tausendschön, J. Kolehmainen, S. Sundaresan, and S. Radl, “Coarse graining Euler-Lagrange simulations of cohesive particle fluidization” Powder Technol, vol. 364, pp. 167–182, Mar. 2020, doi: 10.1016/J.POWTEC.2020.01.056.