Weir and Orifice Flow Equations for a Weir in SWMM 5

Note:  Weir and Orifice Flow Equations for a Weir in SWMM 5

If you use a weir in SWMM 5 then two flow equations are used

1.       The weir uses the weir flow equation when the head at the weir is between the invert elevation of the weir and the crown of the weir and
 2.      An orifice equation when the head is above the weir crown or the weir is submerged.

Weir and Orifice Flow Equations for a Weir in SWMM 5

by dickinsonre
Note:  Weir and Orifice Flow Equations for a Weir in SWMM 5
If you use a weir in SWMM 5 then two flow equations are used
1.       The weir uses the weir flow equation when the head at the weir is between the invert elevation of the weir and the crown of the weir and
2.      An orifice equation when the head is above the weir crown or the weir is submerged.



Comments

Post a Comment

Popular posts from this blog

Orifice and Weir flow calculations

Note: Orifice and Weir Flow Computations The orifice flow calculation proceeds as follows: 1. Initially and whenever the setting (i.e., the fraction opened) changes, flow coefficients for both orifice and weir behavior are computed as follows: a. For side orifices: Define Hcrit = h/2 where h is the opening height. b. For bottom orifices: i. For a circular orifice, compute area over length (i.e., circumference) as AL = h /4. ii. For a rectangular orifice compute AL = h*w/(2*(h+w)) where w is the opening width. iii. Compute Hcrit = Cd*AL/0.414 where Cd is the orifice discharge coefficient. At step 1b, the critical head for the bottom orifice, where orifice flow turns into weir flow, is found by equating the result of the orifice equation to that of the weir equation Cd*Area*sqrt(2g)*sqrt(Hcrit) = Cw*Length*sqrt(Hcrit)*Hcrit or Hcrit = (Cd * Area) / (Cw/sqrt(2g) * Length) The value of Cw/sqrt(2g) for a sharp crested weir is 0.414.
Read more

SWMM 5 Error Messages

Engine Error Number Description ERROR 101: memory allocation error.                                                                                             ERROR 103: cannot solve KW equations for Link                                                                                   ERROR 105: cannot open ODE solver.                                                                                              ERROR 107: cannot compute a valid time step.                                                                                     ERROR 108: ambiguous outlet ID name for Subcatchment                                                                            ERROR 109: invalid parameter values for Aquifer                                                                                  ERROR 110: ground elevation is below water table for Subcatchment                                                         
Read more

EMC Washoff in SWMM5

Image
There are four steps to using EMC concentrations in your network: 1. Define your pollutant by adding a pollutant using the Data=>Quality=>Pollutant command : 2. Define the Land Use by using the Data=>Land Uses command or the Land Use Editor: 3. Define Buildup to be None by clicking on the None Tab: 4. Define the EMC Washoff concentration by clicking on the Washoff Tab: This is where you would add a GW concentration More: http://www.swmm2000.com/
Read more