xsect.c File Reference

Cross-section geometry and hydraulic property evaluation. More...

#include <math.h>
#include "headers.h"
#include "findroot.h"
#include "xsect.dat"

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Classes
struct	TXsectStar

Macros
#define	_CRT_SECURE_NO_DEPRECATE
#define	RECT_ALFMAX   0.97
#define	RECT_TRIANG_ALFMAX   0.98
#define	RECT_ROUND_ALFMAX   0.98

Functions
int	xsect_isOpen (int type)
	Determines if a xsection type is open or closed.
int	xsect_setParams (TXsect *xsect, int type, double p[], double ucf)
	Assigns parameters to a cross section's data structure.
void	xsect_setIrregXsectParams (TXsect *xsect)
	Assigns transect parameters to an irregular shaped cross section.
void	xsect_setStreetXsectParams (TXsect *xsect)
	Assigns transect parameters to a street cross section.
void	xsect_setCustomXsectParams (TXsect *xsect)
	Assigns parameters to a custom-shaped cross section.
double	xsect_getAmax (TXsect *xsect)
	Finds xsection area at maximum flow depth.
double	xsect_getSofA (TXsect *xsect, double a)
	Computes xsection's section factor at a given area.
double	xsect_getYofA (TXsect *xsect, double a)
	Computes xsection's depth at a given area.
double	xsect_getAofY (TXsect *xsect, double y)
	Computes xsection's area at a given depth.
double	xsect_getWofY (TXsect *xsect, double y)
	Computes xsection's top width at a given depth.
double	xsect_getRofY (TXsect *xsect, double y)
	Computes xsection's hydraulic radius at a given depth.
double	xsect_getRofA (TXsect *xsect, double a)
	Computes xsection's hydraulic radius at a given area.
double	xsect_getAofS (TXsect *xsect, double s)
	Computes xsection's area at a given section factor.
double	xsect_getdSdA (TXsect *xsect, double a)
	Computes xsection's derivative of its section factor with respect to area at a given area.
double	xsect_getYcrit (TXsect *xsect, double q)
	Computes critical depth at a specific flow rate.

Variables
double	Amax []

Detailed Description

Cross-section geometry and hydraulic property evaluation.

Author

Caleb Buahin caleb.nosp@m..bua.nosp@m.hin@g.nosp@m.mail.nosp@m..com (OpenSWMM maintenance and extensions)

Copyright

Copyright (c) 2026 Caleb Buahin. OpenSWMM contributions only; original EPA SWMM credits are retained.

License

Apache-2.0 for OpenSWMM contributions; original EPA SWMM provenance is retained.

Macro Definition Documentation

_CRT_SECURE_NO_DEPRECATE

#define _CRT_SECURE_NO_DEPRECATE

RECT_ALFMAX

#define RECT_ALFMAX   0.97

RECT_ROUND_ALFMAX

#define RECT_ROUND_ALFMAX   0.98

RECT_TRIANG_ALFMAX

#define RECT_TRIANG_ALFMAX   0.98

Function Documentation

xsect_getAmax()

double xsect_getAmax

(

TXsect *

xsect

)

Finds xsection area at maximum flow depth.

Parameters

xsect

Ptr. to a cross section data structure.

Returns

Area (ft2).

xsect_getAofS()

double xsect_getAofS	(	TXsect *	xsect,
		double	s )

Computes xsection's area at a given section factor.

Parameters

	xsect	Ptr. to a cross section data structure.
[in]	s	Section factor (ft^(8/3)).

Returns

Area (ft2).

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xsect_getAofY()

double xsect_getAofY	(	TXsect *	xsect,
		double	y )

Computes xsection's area at a given depth.

Parameters

	xsect	Ptr. to a cross section data structure.
[in]	y	Depth (ft).

Returns

Area (ft2).

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xsect_getdSdA()

double xsect_getdSdA	(	TXsect *	xsect,
		double	a )

Computes xsection's derivative of its section factor with respect to area at a given area.

Parameters

	xsect	Ptr. to a cross section data structure.
[in]	a	Area (ft2).

Returns

Derivative of section factor w.r.t. area (ft^2/3).

xsect_getRofA()

double xsect_getRofA	(	TXsect *	xsect,
		double	a )

Computes xsection's hydraulic radius at a given area.

Parameters

	xsect	Ptr. to a cross section data structure.
[in]	a	Area (ft2).

Returns

Hydraulic radius (ft).

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xsect_getRofY()

double xsect_getRofY	(	TXsect *	xsect,
		double	y )

Computes xsection's hydraulic radius at a given depth.

Parameters

	xsect	Ptr. to a cross section data structure.
[in]	y	Depth (ft).

Returns

Hydraulic radius (ft).

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xsect_getSofA()

double xsect_getSofA	(	TXsect *	xsect,
		double	a )

Computes xsection's section factor at a given area.

Parameters

	xsect	Ptr. to a cross section data structure.
[in]	a	Area (ft2).

Returns

Section factor (ft^(8/3)).

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xsect_getWofY()

double xsect_getWofY	(	TXsect *	xsect,
		double	y )

Computes xsection's top width at a given depth.

Parameters

	xsect	Ptr. to a cross section data structure.
[in]	y	Depth ft).

Returns

Top width (ft).

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xsect_getYcrit()

double xsect_getYcrit	(	TXsect *	xsect,
		double	q )

Computes critical depth at a specific flow rate.

Parameters

	xsect	Ptr. to a cross section data structure.
[in]	q	Flow rate (cfs).

Returns

Critical depth (ft).

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xsect_getYofA()

double xsect_getYofA	(	TXsect *	xsect,
		double	a )

Computes xsection's depth at a given area.

Parameters

	xsect	Ptr. to a cross section data structure.
[in]	a	Area (ft2).

Returns

Depth (ft).

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xsect_isOpen()

int xsect_isOpen

(

int

type

)

Determines if a xsection type is open or closed.

Parameters

[in]

type

Type of xsection shape.

Returns

1 if xsection is open, 0 if not.

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xsect_setCustomXsectParams()

void xsect_setCustomXsectParams

(

TXsect *

xsect

)

Assigns parameters to a custom-shaped cross section.

Parameters

xsect

Ptr. to a cross section data structure.

xsect_setIrregXsectParams()

void xsect_setIrregXsectParams

(

TXsect *

xsect

)

Assigns transect parameters to an irregular shaped cross section.

Parameters

xsect

Ptr. to a cross section data structure.

xsect_setParams()

int xsect_setParams	(	TXsect *	xsect,
		int	type,
		double	p[],
		double	ucf )

Assigns parameters to a cross section's data structure.

Parameters

	xsect	Ptr. to a cross section data structure.
[in]	type	Xsection shape type.
	p	Vector of xsection parameters.
[in]	ucf	Units correction factor.

Returns

TRUE if successful, FALSE if not.

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xsect_setStreetXsectParams()

void xsect_setStreetXsectParams

(

TXsect *

xsect

)

Assigns transect parameters to a street cross section.

Parameters

xsect

Ptr. to a cross section data structure.

Variable Documentation

Amax

double Amax[]

Initial value:

= {1.0,    
                 0.9756, 
                 0.9756, 
                 0.97,   
                 1.0,    
                 1.0,    
                 1.0,    
                 1.0,    
                 1.0,    
                 0.98,   
                 0.98,   
                 0.96,   
                 0.96,   
                 0.96,   
                 0.92,   
                 0.96,   
                 0.96,   
                 0.96,   
                 0.98,   
                 0.98,   
                 0.96,   
                 0.96,   
                 1.0,    
                 0.96,   
                 0.9756, 
                 1.0}