Fig. 4.

Sketch of exemplary discretely modeled pulmonary arteries and veins (${\mathrm{\Lambda }}_t$) embedded in the 3D porous domain (${\mathrm{\Omega }}_t$) with the coupling points, i.e., the most distal (away from the heart) node of the discrete embeddings, marked with red circles. Here, $s_k$ describes the spatial position of the coupling point in the discretely modeled blood vessels, and $x(s_k)$ is the spatial position of the coincident point in the 3D porous domain