Integrating legacy components into a software system for storm sewer simulation

This paper presents an approach that integrates a legacy component into a software system for storm sewer simulation. The legacy component employed here is the Storm Water Management Model (SWMM). The Extended Transport (EXTRAN) block of the SWMM that applies the finite difference method (FDM) with explicit numerical schemes, solving the de Saint-Venant equations, is used to route the storm sewer flow. A storm sewer simulation system, named S4, that integrates SWMM-EXTRAN and implements a visualization model, has been developed to demonstrate the proposed approach. The approach makes use of the multi-thread technology to alternate the execution between SWMM-EXTRAN for flow simulation on one thread and the program controller that updates simulation state variables and displays the computed temporal water-stages at the junctions on the other thread at every time step of the FDM process. Two test examples are used to verify and demonstrate the feasibility of the proposed approach. The results show that the multi-thread technology is applied successfully for integrating legacy components, such as SWMM-EXTRAN, into a software system (in this case, S4). In addition, the proposed approach is generally applicable for integrating legacy models or components developed using FDM with explicit numerical schemes.