J. Kim et al., FINITE-ELEMENT MODELING OF SCATTERING PROBLEMS INVOLVING INFINITE DOMAINS USING DRILLING DEGREES OF FREEDOM, Computer methods in applied mechanics and engineering, 134(1-2), 1996, pp. 57-70
Scattering of waves involving complex geometries in conjunction with i
nfinite or semi-infinite domains is modeled by introducing a mathemati
cal boundary within which the finite element representation is employe
d. On the mathematical boundary, the finite element representation is
matched with analytical representation in the infinite/sem-infinite do
main. The matching has been done with and without slope constraints on
the boundary. Drilling degrees of freedom at each of the nodes of the
finite element model are introduced to take into account the transver
se component of the elastodynamic field more precisely. Use of the slo
pe constraint makes the eigenvalues of the mathematical domain complex
and hence reduces the error at those frequencies compared to the use
of field continuity only, which would result in real eigenvalues. Use
of drilling degrees of freedom improves accuracy. Examples involving e
lastic and acoustic wave scattering at the interface of fluid-solid ha
lf spaces are considered. In the examples involving a fluid-solid inte
rface, a method for using displacement formulation in the irrotational
fluid region is also presented. The approach presented here can be ap
plied to acoustic and electromagnetic field problems also.