chapter  4
40 Pages

Simulation of free surface unsteady flow in building drainage networks

The flow regime within building drainage networks is both dominated by, and arguably defined by, the attenuation of appliance discharges as they propagate through the network. Attenuation is apparent in the observed reduction in peak flowrate and depth as the free surface waves generated by an appliance discharge travel through the network with the effect that, at some distance downstream, the flow appears quasi-steady, characterised by reduced flow depth, reduced flowrate and an extended flow duration. Once this zone is reached the simulation of wave action, for example by such techniques as the already discussed Method of Characteristics, is no longer necessary, and more simplistic quasi-steady flow models may be used.