elements.catalog.cavity
elements.catalog.cavity(volume, name='cavity')A lumped finite-volume cavity: a wall to the mean flow, a compliance to acoustics.
Mean-flow-wise the cavity is impermeable – its single port carries mdot = 0, exactly like a :func:wall, so the leg behind it is stagnant and it needs no interior mean unknowns. Acoustically its enclosed gas stores energy: a finite volume V compresses isentropically, giving the lumped compliance C = V / (rho c^2) that populates the storage block M (the i*omega*M term of the operator A = J_alg + i*omega*M + P + S). Paired with a neck inertance (a short :func:duct) off a :func:junction, it forms a Helmholtz resonator with omega_0 = c * sqrt(A_neck / (V * l_eff)) (see :func:helmholtz_resonator).
Although it is a terminal element (single-port), the cavity is not a boundary terminal: its acoustic response is the compliance itself (a reflection set by the storage), so the perturbation layer leaves its inherited mdot' = 0 row in place and lets M add the storage onto it. It is never neutralized or stamped with a reflection coefficient.
The mean state of the cavity gas is tied to its face (the local p, T, composition), so c is the local sound speed. An independently-stated cavity is currently not supported.
Parameters
| Name | Type | Description | Default |
|---|---|---|---|
| volume | float | Enclosed cavity volume V [m^3], strictly positive. Sets the compliance C = V / (rho c^2) and hence the resonance frequency. |
required |
| name | str | Element label. | 'cavity' |
Returns
| Name | Type | Description |
|---|---|---|
| ElementSpec |