openswmm::hydkernels Namespace Reference

Classes
struct	CulvertCurve
	Inlet-control curve coefficients for one culvert type code. More...

Functions
OPENSWMM_KERNEL_FN double	fricSlopeHW (double velocity, double hyd_rad, double c_hw) noexcept
	Compute Hazen-Williams friction slope from velocity and hydraulic radius.
OPENSWMM_KERNEL_FN double	fricSlopeDW (double velocity, double hyd_rad, double roughness) noexcept
	Compute Darcy-Weisbach slope with laminar or Swamee-Jain friction factor.
OPENSWMM_KERNEL_FN double	culvertInflow (double q_proposed, double head, double y_full, double a_full, double slope, const CulvertCurve &cc, bool mitered, double &dqdh) noexcept
	Limit proposed culvert flow by a three-regime inlet-control curve.

Variables
constexpr double	kViscosity = 1.1e-5
constexpr double	kGravity = 32.2
	Gravity in internal units, matching constants::GRAVITY.

Function Documentation

culvertInflow()

OPENSWMM_KERNEL_FN double openswmm::hydkernels::culvertInflow ( double q_proposed, double head, double y_full, double a_full, double slope, const CulvertCurve & cc, bool mitered, double & dqdh )

noexcept

Limit proposed culvert flow by a three-regime inlet-control curve.

Uses unsubmerged h/D<=0.95, submerged above derived transition, linear interpolation between. No global finite/geometry validation, donor cap or sign handling.

Parameters

[in]	q_proposed	Nonnegative proposed native cfs discharge.
[in]	head	Upstream headwater above invert ft; nonpositive bypasses control.
[in]	y_full	Positive full culvert depth ft; nonpositive bypasses.
[in]	a_full	Positive full area ft2; nonpositive bypasses.
[in]	slope	Finite conduit slope ft/ft used for inlet correction.
[in]	cc	Borrowed valid FHWA coefficients K/M/C/Y; K=0 bypasses, physical branches require valid positive divisors.
[in]	mitered	True uses-7*slope correction, false+0.5*slope.
[out]	dqdh	Set0 first, then derivative of the inlet curve in cfs/ft when evaluated; can remain nonzero even if q_proposed is the returned minimum.

Returns

min(proposed,inlet) cfs on evaluated branch; proposed unchanged for bypass/invalid curve arguments.

fricSlopeDW()

OPENSWMM_KERNEL_FN double openswmm::hydkernels::fricSlopeDW ( double velocity, double hyd_rad, double roughness )

noexcept

Compute Darcy-Weisbach slope with laminar or Swamee-Jain friction factor.

Uses diameter4R, viscosity1.1e-5ft2/s and gravity32.2ft/s2. Re<=2000 selects64/Re; higher selects explicit turbulent approximation. No transition blending or general finite guard.

Parameters

[in]	velocity	Signed native ft/s, magnitude used.
[in]	hyd_rad	Positive native ft radius; <=0 returns0.
[in]	roughness	Nonnegative absolute roughness height ft, caller-validated.

Returns

Dimensionless nonnegative friction slope for finite physical inputs;0 for nonpositive radius/Re or logarithm argument.

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fricSlopeHW()

OPENSWMM_KERNEL_FN double openswmm::hydkernels::fricSlopeHW ( double velocity, double hyd_rad, double c_hw )

noexcept

Compute Hazen-Williams friction slope from velocity and hydraulic radius.

Uses (abs(v)/(1.318*C*R^0.63))^(1/0.54); no general finite checks or source-direction sign.

Parameters

[in]	velocity	Signed ft/s velocity; formula uses magnitude.
[in]	hyd_rad	Positive hydraulic radius ft; <=0 returns0.
[in]	c_hw	Positive Hazen-Williams C coefficient; <=0 returns0.

Returns

Dimensionless nonnegative friction slope for finite physical inputs.

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Variable Documentation

kGravity

double openswmm::hydkernels::kGravity = 32.2

inlineconstexpr

Gravity in internal units, matching constants::GRAVITY.

kViscosity

double openswmm::hydkernels::kViscosity = 1.1e-5

inlineconstexpr

Kinematic viscosity of water, ft²/s. Spelled here rather than included so the header stays dependency-free for the plugin build; it must equal constants::VISCOS, and a static_assert in ForceMain.cpp holds it to that.