openswmm::forcemain Namespace Reference

Enumerations
enum class	FrictionModel : int {   HAZEN_WILLIAMS = 0 ,   DARCY_WEISBACH = 1 }

Functions
double	getFricSlope_HW (double velocity, double hyd_rad, double c_hw)
	Compute friction slope for Hazen-Williams.
double	getFricSlope_DW (double velocity, double hyd_rad, double roughness)
	Compute friction slope for Darcy-Weisbach.
double	getFricFactor (double r_bot, double hrad, double re)
	Compute friction factor f (Darcy-Weisbach) for fully-turbulent flow.
double	getEquivN (FrictionModel model, double r_bot, double y_full, double slope, double n_raw)
	Compute equivalent Manning's n for a force main (Gap #22).
double	getRoughFactor (FrictionModel model, double r_bot, double length_factor)
	Compute roughness adjustment factor for a force main (Gap #22).
void	batchFricSlope (const double *velocity, const double *hyd_rad, const double *param, double *fric_slope, FrictionModel model, int count)
	Batch compute friction slopes for all force mains — VECTORISABLE.

Variables
constexpr double	VISCOS = 1.1e-5
	Kinematic viscosity @ 20C (ft2/sec)

Enumeration Type Documentation

FrictionModel

enum class openswmm::forcemain::FrictionModel : int

strong

Enumerator
HAZEN_WILLIAMS
DARCY_WEISBACH

Function Documentation

batchFricSlope()

void openswmm::forcemain::batchFricSlope	(	const double *	velocity,
		const double *	hyd_rad,
		const double *	param,
		double *	fric_slope,
		FrictionModel	model,
		int	count
	)

Batch compute friction slopes for all force mains — VECTORISABLE.

Parameters

velocity	[in] Velocity array (indexed by force-main group).
hyd_rad	[in] Hydraulic radius array.
param	[in] C_HW or roughness height, depending on model.
fric_slope	[out] Friction slope array.
model	Hazen-Williams or Darcy-Weisbach.
count	Number of force mains.

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getEquivN()

double openswmm::forcemain::getEquivN	(	FrictionModel	model,
		double	r_bot,
		double	y_full,
		double	slope,
		double	n_raw
	)

Compute equivalent Manning's n for a force main (Gap #22).

For DW routing with a force main, the Manning's n equivalent that produces the same full-pipe normal flow as the HW or DW formula. Matches legacy forcemain_getEquivN() in forcmain.c.

Parameters

model	Friction model (HAZEN_WILLIAMS or DARCY_WEISBACH).
r_bot	Hydraulic radius parameter stored in xsect (rBot in legacy): for HW: the C-factor; for DW: roughness height (ft).
y_full	Full-pipe depth (ft).
slope	Conduit slope (ft/ft, positive).
n_raw	Raw Manning's roughness (fallback if model unrecognized).

Returns

Equivalent Manning's n.

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getFricFactor()

double openswmm::forcemain::getFricFactor	(	double	r_bot,
		double	hrad,
		double	re
	)

Compute friction factor f (Darcy-Weisbach) for fully-turbulent flow.

Used internally by getEquivN for DW force mains. Matches legacy forcemain_getFricFactor() in forcmain.c at Re=1e12.

Parameters

r_bot	Roughness height (ft).
hrad	Hydraulic radius (ft).
re	Reynolds number (use 1e12 for fully turbulent).

Returns

Darcy-Weisbach friction factor f.

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getFricSlope_DW()

double openswmm::forcemain::getFricSlope_DW	(	double	velocity,
		double	hyd_rad,
		double	roughness
	)

Compute friction slope for Darcy-Weisbach.

Parameters

velocity	Flow velocity (ft/sec).
hyd_rad	Hydraulic radius (ft).
roughness	Pipe roughness height (ft).

Returns

Friction slope Sf (dimensionless).

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getFricSlope_HW()

double openswmm::forcemain::getFricSlope_HW	(	double	velocity,
		double	hyd_rad,
		double	c_hw
	)

Compute friction slope for Hazen-Williams.

Parameters

velocity	Flow velocity (ft/sec).
hyd_rad	Hydraulic radius (ft).
c_hw	Hazen-Williams C coefficient.

Returns

Friction slope Sf (dimensionless).

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getRoughFactor()

double openswmm::forcemain::getRoughFactor	(	FrictionModel	model,
		double	r_bot,
		double	length_factor
	)

Compute roughness adjustment factor for a force main (Gap #22).

The returned value is stored in xsect_s_bot and used by getFricSlope_HW / getFricSlope_DW to compute friction slope. Matches legacy forcemain_getRoughFactor() in forcmain.c.

Parameters

model	Friction model.
r_bot	rBot parameter (C for HW, roughness height for DW).
length_factor	Factor by which the conduit was artificially lengthened.

Returns

Roughness factor stored in xsect.sBot.

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Variable Documentation

VISCOS

constexpr double openswmm::forcemain::VISCOS = 1.1e-5

constexpr

Kinematic viscosity @ 20C (ft2/sec)