Three ways to compute multiport inertance
Authors: McBain Geordie Drummond 
Published: August 2019

The immediate impulse-response of a confined incompressible fluid is characterized by inertance. For a vessel with one inlet and outlet, this is a single quantity; for multiple ports the generalization is a singular reciprocal inertance matrix which acts on the port-impulses to give the corresponding inflows. The reciprocal inertance coefficients are defined by the boundary fluxes of potential flows. Green's identity converts these coefficients to domain integrals of kinetic energy. For a system discretized with finite elements, a third method is proposed for computing reciprocal inertance coefficients which requires only the stiffness matrix and the solution vectors and no numerical differentiation.

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