SWMM56

Subject:   An Example of the Importance of the Term DQ4 in the SWMM 5 St Venant Solution 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 based on the Froude number, Ignore sets Sigma to 0 all  of the time during the simulation. The value of dq4 increases when there is a significant difference in the cross sectional  area of the downstr...

Subject:   An Example of the Importance of the Term DQ4 in the SWMM 5 St Venant Solution An Example of the Importance of the Term DQ4 in the SWMM 5 St Venant Solution by  dickinsonre Subject:    An Example of the Importance of the Term DQ4 in the SWMM 5 St Venant Solution 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 based...