Coupling of Boundary Elements with Other Methods

Many engineering problems present a certain amount of coupling or interaction between different parts or systems. For instance, systems representing structure, fluid, and soil can be coupled within the same problem, each part represented by a physical region over which a particular numerical solution can be applied. Fluids such as water, air, or lubricants may be interacting against structural elements such as buildings, dams, offshore structures, mechanical components, pressure vessels, etc. Surface structures interact with the soil through their foundations and the behavior of buried structures is strongly coupled with the surrounding rock or soil strata. In many cases it is possible to assume that for all practical purposes, the effect of one system upon the other does not occur concurrently. Typical examples of this uncoupled behavior are wind forces on stiff buildings and hydrodynamic forces on massive off-shore gravity platforms. For these cases the forces on the structure can be computed assuming that the structure is rigid and neglecting the interaction with the surrounding fluid. Boundary elements are recommended to solve these problems due to their ability to model domains extending to infinity. Problems such as wave diffraction, harbor resonance, fluid flow, etc., have been frequently solved using boundary elements. For these cases the boundary element technique offers a very simple data input by comparison with methods such as finite elements of finite differences.