In this paper, we introduce a class of lowest-order nonconforming immersed finite element (IFE) methods for solving two-dimensional Stokes interface problems. The proposed do not require the solution mesh to align with fluid and can use either triangular or rectangular meshes. On meshes, Crouzeix–Raviart is used velocity approximation, piecewise constant pressure. Rannacher–Turek rotated Q1-Q0 ...

At the fluid/porous-medium interface the pseudo-Rayleigh (pR) and pseudo-Stoneley (pSt) waves exist. The relation with the corresponding poles in the slowness plane is not unambiguous, depending on the choice of branch cuts. For a point-force excitation, the far-field Green's functions are computed using vertical branch cuts (method I) implying that the pR- and pSt-poles obey the radiation cond...