The Keep and Dampen options and their effect on the four main terms of the St Venant equation in SWMM5
Note: The Keep and Dampen options and their effect on the four main terms of the St Venant equation . The four terms are are used in the new flow for a time step of Qnew: Qnew = (Qold – dq2 + dq3 + dq4) / ( 1 + dq1) when the force main or gravity main is full dq3 and dq4 are zero and Qnew = (Qold – dq2) / ( 1 + dq1) The dq4 term in dynamic.c uses the area upstream ( a1 ) and area downstream ( a2 ), the midpoint velocity, the sigma factor (a function of the link Froude number), the link length and the time step or dq4 = Time Step * Velocity * Velocity * (a2 – a1) / Link Length * Sigma where Sigma is a function of the Froude Number and the Keep , Dampen and Ignore Inertial Term Options . Keep sets Sigma to 1 always and Dampen set Sigma base...