Improving and Testing SWMM5+

The SWMM5+ finite-volume hydraulic solver is available to the public as open-source code but is still undergoing debugging, testing and improvement. Recent work includes a new algorithm that replaces short lengths of pipe with an "equivalent orifice." The equivalent orifice has some similarities to the pipe lengthening approach used in EPA SWMM but provides larger time steps for the finite-volume solver. At the cutting edge of new capabilities is including trapped air in a conduit, which can dramatically change the pressurization behavior during rapid filling. Debugging and testing of the code has lead to refactoring of the parallel decomposition algorithm that assigns different parts of a system to parallel processors. We have also recently uncovered finite-volume errors in the overflow and ponding algorithms, which are undergoing code refactoring and further testing.