Preliminary Study of the Vertical Stack to Horizontal Drain Entry Condition as an Extension to the Modeling of Unsteady Partially Filled Pipe Flow

摘要

The finite difference based method of characteristics model for unsteady partially filled pipe flow was extended to include the stack to horizontal drain entry boundary condition. The conditions at drain entry are defined in terms of the energy of the terminal annular flow velocity in the stack, together with an appropriate loss coefficient as the entry function. The hydraulic solutions link the branch drains, fittings, vertical soil stack and building drain. The analysis permits any combination of drainage load patterns from simultaneous, overlapping or sequence of discharge events. Preliminary simulations utilizing this model indicates that the modeling technique extends the existing horizontal network analysis program to a simulation of multistory building drainage systems. The sizing procedure determines the hydraulic capacity of drains for specified pipe sizes, pipe pitch and well roughness factors.