SWMM 5.2.2 Underdrain System (part of Storage Layer) Code

 

Variable Name	Type	Description
coeff	double	underdrain flow coefficient (in/hr or mm/hr)
expon	double	underdrain head exponent (for in or mm)
offset	double	offset height of underdrain (ft)
delay	double	rain barrel drain delay time (sec)
hOpen	double	head when drain opens (ft)
hClose	double	head when drain closes (ft)
qCurve	int	curve controlling flow rate (optional)

This code defines a struct called TDrainLayer, which represents an underdrain system as part of a storage layer. The struct contains several variables:

• coeff: a double representing the underdrain flow coefficient, in units of in/hr or mm/hr.
• expon: a double representing the underdrain head exponent, used to calculate the head loss through the underdrain.
• offset: a double representing the offset height of the underdrain, in feet.
• delay: a double that represents the delay time for the rain barrel drain, in seconds.
• hOpen: a double representing the head at which the drain opens, in feet.
• hClose: a double representing the head at which the drain closes, in feet.
• qCurve: an integer that represents the curve controlling the flow rate of the underdrain. This is optional and may not be used in all cases.

The struct is used to store information about the underdrain system, which can then be used in various calculations and simulations related to the storage layer.

// Underdrain System (part of Storage Layer) typedef struct { double coeff; // underdrain flow coeff. (in/hr or mm/hr) double expon; // underdrain head exponent (for in or mm) double offset; // offset height of underdrain (ft) double delay; // rain barrel drain delay time (sec) double hOpen; // head when drain opens (ft) double hClose; // head when drain closes (ft) int qCurve; // curve controlling flow rate (optional) } TDrainLayer;