Abstract: In this paper, some essential problems in the assembling of multi-level substructuring are discussed, which include the referencing of superelements in the substructural module and respective expression; the automatic formation of the node sequence as well as the qualification number of these nodes in the substructural modules.All the ideas mentioned above have been implemented in the general purpose structural analysis program JIGFEX. The assembling consideration is one of the most important practical problems in the structural analysis computer program design by the multi-level substructuring approach. In this paper those problems are discussed only from the theoretical aspect and all the practical implementation and applications are neglected however.

Key words: unsteady three-dimensional model, flow across the arterial wall, macromolecular transportation, atherosclerosis, concentration distribution