Seminar - Alvaro Ramirez-Gomez - Discrete Element Modelling
Wednesday 5 October 2011, 1.30 pm - 2.00 pm
Lecture Room 3, School of Civil Engineering
Associate Professor Alvaro Ramirez-Gomez
Universidad Politecnica de Madrid, Spain
Álvaro completed his PhD obtaining the accreditation of “European doctorate” at The Technical University of Madrid in 2007. His initial research topic was pressure measurements in full-scale steel silos. He visited Prof. Jin Ooi and Prof. Michael Rotter at the University of Edinburgh in 2004 and afterwards, he visited Prof. Jorgen Nielsen several times at the Danish Building Research Institute-University of Aalborg establishing a strong collaboration. At the end of his PhD, he contacted with Prof. Peter Ansourian and Prof. Itai Einav at the University of Sydney where he was developing Discrete Element analysis in order to get a better understanding of the behaviour of soft pressure cells. He has been visiting the University of Sydney several times, nowadays he is collaborating with Fernando Alonso-Marroqu'n in granular flow. Among the activities carried out during these years are the determination of mechanical properties of biomass materials as well as the ignitability and explosibility properties, design of pressure cells, and design of a test silo for explosions.
He is part of the Working Group “Mechanics of Particulate Solids” of the European Federation of Chemical Engineers.
A discrete element model of a 3D silo with a squared cross-section and a wedge hopper at its base has been developed to correctly simulate different stored materials (glass beads and corn grains) during filling and discharge processes. The vertical section of the silo is 0.5 m height and 0.25 m width whereas the hopper is 0.186 m height. The experimental validation of this numerical model consisted in comparing results from the simulations with results derived from experimental tests with glass bead and corn grains in a silo with similar dimensions. The force-displacement law used to model the particle interaction is based on the Hertz-Mindlin no-slip contact model with viscous damping and a frictional slider in the tangential direction of the contact. The two types of particles considered (glass beads and corn grains) were simulated respectively using single spheres and multi-spherical particles. The values of the microscopic properties of each material were previously determined (elasticity modulus, friction coefficient, particle density, restitution coefficient etc.) and were modified when necessary during the validation process. The results allow assessing whether DEM is capable of reproducing the expected behaviour and if it may contribute to understand some important phenomena occurring during silo filling and discharge.