Examining the smooth and nonsmooth discrete element approaches to granular matter
2014 (English)In: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 97, no 12, 878-902 p.Article in journal (Refereed) Published
The smooth and nonsmooth approaches to the discrete element method (DEM) are examined from a computational perspective. The main difference can be understood as using explicit versus implicit time integration. A formula is obtained for estimating the computational effort depending on error tolerance, system geometric shape and size, and on the dynamic state. For the nonsmooth DEM (NDEM), a regularized version mapping to the Hertz contact law is presented. This method has the conventional nonsmooth and smooth DEM as special cases depending on size of time step and value of regularization. The use of the projected Gauss-Seidel solver for NDEM simulation is studied on a range of test systems. The following characteristics are found. First, the smooth DEM is computationally more efficient for soft materials, wide and tall systems, and with increasing flow rate. Secondly, the NDEM is more beneficial for stiff materials, shallow systems, static or slow flow, and with increasing error tolerance. Furthermore, it is found that just as pressure saturates with depth in a granular column, due to force arching, also the required number of iterations saturates and become independent of system size. This effect make the projected Gauss-Seidel solver scale much better than previously thought.
Place, publisher, year, edition, pages
John Wiley & Sons, 2014. Vol. 97, no 12, 878-902 p.
discrete element method;multibody dynamics, granular media, contact, explicit time integration, linear solvers
IdentifiersURN: urn:nbn:se:umu:diva-87019ISI: 000331358000002OAI: oai:DiVA.org:umu-87019DiVA: diva2:710790