elements.catalog.isentropic_area_change

elements.catalog.isentropic_area_change(
    name='iac',
    l_up=0.0,
    l_down=0.0,
    end_correction=0.0,
)

A smooth (lossless) contraction or diffuser; optionally length-bearing to model acoustic inertance and compliance (not propagation).

By default a lengthless jump. A real diffuser/nozzle has axial extent, so the optional l_up/l_down (the passage half-lengths on the port-0 / port-1 sides) give it acoustic compliance (each side stores l_i * A_i of gas) and inertance (series effective length l_up + l_down + end_correction, referenced to the throat). These populate the storage block M and are inert in the mean flow.

Parameters

Name Type Description Default
name str Element label. 'iac'
l_up float Passage half-length [m] on the port-0 (upstream) / port-1 (downstream) side. 0.0
l_down float Passage half-length [m] on the port-0 (upstream) / port-1 (downstream) side. 0.0
end_correction float Added-mass length [m] added to the inertance only (the entrained near-field the geometric length omits). 0.0
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