Research Paper: SEdStructures and Environment Simulation of three-dimensional airflow in grain storage bins O.A. Khatchatourian a,b, *, M.O. Binelo b a Department of Physics, Statistics and Mathematics, Regional University of the Northwest, Rio Grande do Sul, R. Sa ˜o Francisco, 501, 98700-000 IJUI ´ , RS, Brazil b Computer Science Department, University of Cruz Alta, R. Andrade Neves, 308, 98025-810 Cruz Alta, RS, Brazil article info Article history: Received 21 August 2007 Received in revised form 29 May 2008 Accepted 4 June 2008 Published online 21 August 2008 A mathematical model and software were developed for the three-dimensional simulation of airflow through high capacity grain storage bins by considering the non-uniformity of the seed mass. To validate the proposed model, empirical relationships between air velocity and static pressure drop were obtained for compacted layers of several storage depths for soya bean, maize, rice and wheat mass. The software was written in ANSI Cþþ which is transferable to a variety of platforms. For the construction of 3D geometry and the generation of meshes free-of-charge software was used. The solver software generated a system of linear algebraic equations using the finite -element method. Three iterative processes were carried out: (1) cal- culation of a local permeability coefficient, using the pressure distribution in the immediately previous iteration step, (2) search for the system design point, located in the performance curve of the aerator fan, and (3) adaptation to refine the mesh. A local criterion to estimate the effi- ciency of complex aeration system in storage bins was proposed. The simulations showed good performance. It was considered that the method could be applied to optimise the perfor- mance of existing grain stores and lower the engineering costs of new grain stores. ª 2008 IAgrE. Published by Elsevier Ltd. All rights reserved. 1. Introduction Aeration is widely used in grain stores to cool the grain mass, to avoid humidity migration, to temporarily conserve the hu- midity of grains, to remove scents from the grain mass, and to apply fumigation. The resistance to the airflow in an aeration system depends on the airflow parameters, on the characteristics of the prod- uct surface (i.e. rugosity), on the form and size of any extrane- ous impurity in the mass, on the configuration and size of the interstitial space in the mass, on the size and amount of bro- ken grains, and on the depth of the grain. The research carried out by Shedd (1953), Brooker (1961, 1969), Brooker et al. (1982), Bunn and Hukill (1963), Pierce and Thompson (1975), Haque et al. (1981), Ribeiro et al. (1983), Jayas et al. (1987), Maier et al. (1992), Weber (1995), Khatchatourian et al. (2000), Navarro and Noyes (2001), Khatchatourian and Savicki (2004), and Khatchatourian and de Oliveira (2006) has examined the influence of some of these parameters on air- flow pattern in seeds storage. A recent review of the reported mathematical models of airflow through grain mass was pre- sented by Gayathri and Jayas (2007). With increasing depth of grain storage, the mass of grain can no longer be assumed homogeneous. Non-homogeneity can significantly alter the physical parameters involved in the aeration process, such as air velocity and static pressure drop. However, there is no research relating compaction of the grain and the airflow pattern under these conditions. * Corresponding author. Department of Physics, Statistics and Mathematics, Regional University of the Northwest, Rio Grande do Sul, R. Sa ˜ o Francisco, 501, 98700-000 IJUI ´ , RS, Brazil. E-mail addresses: olegkha@unijui.edu.br (O.A. Khatchatourian), mbinelo@yahoo.com.br (M.O. Binelo). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/issn/15375110 1537-5110/$ – see front matter ª 2008 IAgrE. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.biosystemseng.2008.06.001 biosystems engineering 101 (2008) 225–238