ALGEBRAIC DISCRETE NONLOCAL (DNL) ABSORBING BOUNDARY-CONDITION FOR THE SHIP WAVE RESISTANCE PROBLEM

An absorbing boundary condition for the ship wave resistance problem i s presented. In contrast to the Dawson-like methods, it avoids the use of numerical viscosities in the discretization, so that a centered sc heme can be used for the free surface operator. The absorbing boundary condition is ''completely absorbing,'' in the sense that the solution is independent of the position of the downstream boundary and is deri ved from straightforward analysis of the resulting constant-coefficien ts difference equations, assuming that the mesh is 1D-structured fin t he longitudinal direction) and requires the eigen-decomposition of a m atrix one dimension lower than the system matrix. The use of a centere d scheme for the free surface operator allows a full finite element di scretization. The drag is computed by a momentum flux balance. This me thod is more accurate and guarantees positive resistances. (C) 1998 Ac ademic Press