marenv::wake::JetProfile Class Reference

#include <PropellerJet.h>

Public Member Functions
	JetProfile (const JetSourceInput &input)
bool	Active () const
	True if the jet casts anything: T_eff > 0.
double	AdvanceSpeed () const
	The co-flow speed U = max(u_a, 0), m/s.
double	Efflux () const
	The efflux velocity Δu₀, m/s; 0 when not active.
double	InitialSigma () const
	sigma_0 = D_p / sqrt(8), m.
double	ZoneEnd () const
	x_0 = sigma_0 / c, the end of the zone of flow establishment, m.
double	RampLength () const
	L_ramp = kJetRampFactor D_p, m.
double	VelocityScale () const
	The jet's velocity scale U + Δu₀, m/s, against which MayReach() applies a cutoff.
JetCentreline	At (double x) const
	Centreline amplitude, the onset ramp included, and sigma at x, m downstream of the propeller plane.
double	CentrelineExcess (double sigma) const
	The centreline excess Δu_c = sqrt(U^2 + q / sigma^2) - U at width sigma, m/s.
double	DistanceAt (double sigma) const
	The distance x(sigma) >= x_0 at which the established jet has width sigma >= sigma_0, m (closed form).
double	SigmaAt (double x) const
	The width sigma(x) of the established jet at x >= x_0, m (inverse of DistanceAt()).
double	PeakAmplitude (double xFrom, double xTo) const

Detailed Description

The law of one propeller jet along its axis (doc/wake.md § 4.2), built once per publish.

With U = max(u_a, 0), q = T_eff / (rho pi) and c = kJetSpreadingRate:

• efflux Δu₀ = sqrt(U^2 + 8 T_eff / (rho pi D_p^2)) - U (actuator disc), evaluated without cancellation;
• sigma_0 = D_p / sqrt(8), x_0 = sigma_0 / c (1.96 D_p), L_ramp = kJetRampFactor D_p (0.5 D_p);
• x < 0: 0; 0 <= x <= x_0: amplitude S(x / L_ramp) Δu₀, sigma = sigma_0 (S the onset ramp, OnsetRamp());
• x > x_0: sigma(x) the inverse of the closed-form x(sigma) of dsigma/dx = c Δu_c / (U + Δu_c), found by safeguarded Newton steps, and Δu_c = sqrt(U^2 + q / sigma^2) - U, so that rho pi sigma^2 (2 U Δu_c + Δu_c^2) = T_eff at every x from the end of the ramp on. T_eff <= 0 casts nothing (Active() false, amplitude 0).

Constructor & Destructor Documentation

JetProfile()

marenv::wake::JetProfile::JetProfile ( const JetSourceInput &  input )

explicit

Parameters

[in]

input

The jet's source; propellerDiameter and rho positive, the strength finite (not checked here: PropellerJet::Publish() validates).

Member Function Documentation

PeakAmplitude()

double marenv::wake::JetProfile::PeakAmplitude	(	double	xFrom,
		double	xTo
	)		const

Upper bound of At(x).amplitude for x in [xFrom, xTo], 0 <= xFrom <= xTo, m.

The amplitude rises over the ramp, is Δu₀ up to x_0 and falls beyond, so the bound is S(xTo / L_ramp) Δu₀ for xTo <= L_ramp, Δu₀ if xFrom <= x_0, else the amplitude at xFrom.

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The documentation for this class was generated from the following file:

• webfhsim/reloadrepos/marenv/include/marenv/wake/PropellerJet.h