The Equivalent n for Hazen-Williams in a Force Main of SWMM 5
SWMM 5 uses an equivalent Manning's n for the Hazen-Williams Coefficient for partial flow in a force main of SWMM 5. The equivalent n is a function of the force main diameter, slope and the power equation used by Lew Rossman of the EPA in the SWMM 5 C code in the routine forcemain_getEquivN. I am also including the C code to print out the HW value, diameter, slope and Equivalent n in the output file. It is easy to add new of code to SWMM 5 for your thesis as long as you have a compiler (I suggest the current free Visual Studio from Microsoft) and know how to add the fprintf statements. This simple addition gives you the power to understand more fully the inner working of SWMM 5 and add more content and understanding to your thesis or paper.