Name: SpectraSim
Availability: InStock

Theory

For $n$ inlets the reference pipe is a trunk along $x$ with one branch per inlet, each tilted 45° from the trunk axis and spread evenly around it (two inlets give a flat Y).

Branch $i$ starts on the trunk axis at $x_{0,i}$ , equation (1), so that its whole base disc lies inside the trunk.
It runs a length $B$ along the direction of equation (2), out through the end plate of the trunk.
Its inlet face is therefore a flat disc a full branch length from the junction: a straight, uniform duct for the port modes.

The union is meshed as one fluid volume with rigid walls.

Equations

x_{0,i} = r_i \sin\theta, \qquad \theta = 45^\circ

(1)

\mathbf{u}_i = \left(-\cos\theta,\ \sin\theta\cos\varphi_i,\ \sin\theta\sin\varphi_i\right), \qquad \varphi_i = \frac{2\pi i}{n}

(2)

where	meaning	unit
$x_{0,i}$	Axial position of the base centre of branch $i$	m
$r_i$	Radius of branch $i$ (equal-area circle of its inlet)	m
$\theta$	Angle between a branch and the trunk axis	°
$\mathbf{u}_i$	Direction of branch $i$ , from the trunk to its inlet	-
$\varphi_i$	Angular position of branch $i$ round the trunk	rad
$n$	Number of inlets	-

Default and rule

Default: 1 m
Rule: 1 m. This is the program's default; it is not derived from a published rule.
Source: The geometry is the program's own construction. The branches are fused onto the trunk one at a time and the resulting volume is checked, because a single fusion of several overlapping branches can return an incorrect solid in the CAD kernel.

Valid range > 0; several inlets only

Values

Above 0. Not used with a single inlet.

Theory

Equations

Default and rule

Valid range > 0; several inlets only

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