Hydrodynamic pressure analysis of dam–reservoir systems using a scaling center surface based scaled boundary finite element method

Earthquake-induced hydrodynamic pressure is an important component of the seismic demand on dam–reservoir systems, particularly when the reservoir geometry departs from ideal prismatic assumptions. Analytical solutions provide useful benchmarks, but they are usually restricted to simplified dam faces, reservoir bottoms, and boundary conditions. Conventional numerical approaches can handle more general configurations, but often require volumetric fluid discretization and artificial far-field boundary treatments. This study applies the scaling center surface based scaled boundary finite element method to frequency-domain hydrodynamic pressure analysis of compressible reservoir water. Within this framework, the scaled boundary transformation is constructed through corresponding nodal pairs between a prescribed scaling center surface and the upstream dam face. The acoustic governing equation is derived in scaled coordinates by considering the free-surface condition, dam–reservoir interface excitation, and impedance-type absorbing boundaries. The resulting radial equation is solved using a Hamiltonian/Riccati formulation, in which the far-field decay condition is imposed through the stable invariant subspace. A segmented matrix-fitting strategy is incorporated to approximate the variable coefficient matrices during Runge–Kutta integration. The method is verified using a two-dimensional rigid gravity dam benchmark, a three-dimensional rigid arch dam comparison with the Abaqus acoustic–structure coupling method, mesh-refinement tests, and reservoir-geometry sensitivity analyses. The results show good agreement with reference solutions and capture the main depth-dependent pressure distribution. In the arch-dam comparison, the maximum error is 4.95% relative to the maximum reference pressure, and the node-by-node comparison gives an R 2 value of 0.98662. The resulting formulation provides a boundary-oriented procedure for hydrodynamic pressure analysis of dam–reservoir systems with nonuniform reservoir geometry.