Volpato, S., Artoni, R., Santomaso, A.C. Numerical study on the behavior of funnel flow silos with and without inserts through a continuum hydrodynamic approach (2014) Chemical Engineering Research and Design, 92, pp. 256-263. DOI: 10.1016/j.cherd.2013.07.030 Numerical study on the behavior of funnel flow silos with and without inserts through a continuum hydrodynamic approach Silvia Volpato 1 , Riccardo Artoni 2 , Andrea C. Santomaso 1 * 1 APTLab – Advanced Particle Technology Laboratory, Dipartimento di Ingegneria Industriale, Università di Padova, via Marzolo, 9 - 35131 Padova PD, Italy 2 L’UNAM / IFSTTAR, Route de Bouaye CS4 44344 Bouguenais, France *corresponding author: andrea.santomaso@unipd.it Abstract In this paper the results from simulations performed using a hydrodynamic model proposed by Artoni et al. [Chem. Eng. Sci. 64 (2009a), 4040-4050] have been compared with published data of an extensive experimental investigation carried out at the Tel-Tek Research Institute in Porsgrunn, Norway. The experiments collected several data and observations on the wall stresses and the flow patterns observed during discharge of a full-scale funnel flow silo with and without inserts. The comparison between simulation and experiments showed the ability of the model to capture quantitatively the main features of both the flow and of the wall stress profiles when flow corrective inserts are put in the hopper of the silo in order to convert the discharge regime to a mass flow regime. Moreover information such as the stresses on the internals, which are difficult or impossible to get experimentally, have been collected from the simulations and discussed. Introduction Industrial granular flows in confined geometries as those present in silos can present important issues with respect to both the velocity and the stress fields. The discharge flow regime might need to be improved in order to keep residence times of the material sufficiently uniform, to avoid the formation of stagnant zones or to reduce segregation. This corresponds working in the mass flow regime instead of the funnel or core flow regimes. Also the understanding and prediction of stresses is crucial because of the need to prevent problems such as particles comminution, arching or even silo collapse (Schulze, 2008). The most important distinguishing feature of mass flow is that all the particles in the hopper of the silo start to move when the outlet is opened. A hopper designed for mass flow is characterized by the relatively tall converging section with steep walls, by the absence of sharp transitions and the relatively large outlet. For most purposes mass flow is the preferable flow pattern. Silos with shallow hoppers, which are prone to induce funnel flow, can be however encountered to store large amounts of material mostly when the headroom is limited. One possibility for avoiding problems related to funnel flow is to promote mass flow by retrofitting the hopper with specific inserts. An insert, when correctly designed and positioned, can reduce stagnant zones in a silo with a relatively shallow hopper, leading to a flow pattern approaching mass flow. Notwithstanding the existence of some design rules (Jenike,1966; Johanson, 1968) challenges still remain in the design and the correct placement of an insert and there is still too little knowledge about the effect of inserts on flow patterns and wall stresses (Härtl et al., 2008). For example little changes in the vertical positioning of the insert are generally © 2014. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/