Efficient junction sequence method for transport in a directed network

A new junction sequence method for taking into account transport in a direc ted network of interconnected channels is suggested. It is a slight modific ation of the pathway and tree methods but is much more efficient. The requi rements of the method in terms of computing time increases only linearly wi th the size of the network and sublinearly in terms of memory. The increase d efficiency results from the introduction of a global order for the juncti ons in the network, which defines a sequence of the junctions such that tra nsport at a junction only depends on preceding junctions but not on followi ng junctions in the sequence. With this method the transport in the entire network can be calculated at "one shot" instead by superimposing a large nu mber of pathways. The capabilities for some nonlinear effects like nonlinea r sorption goes beyond the present pathway and tree methods.