In this paper, a robust local polynomial collocation method is presented. Based on collocation, this method is rather simple and straightforward. The present method is developed in a way that the governing equation is satisfied on boundaries as well as boundary conditions. This requirement makes the present method more accurate and robust than conventional collocation methods, especially in estimating the partial derivatives of the solution near the boundary. Studies about the sensitivity of the shape parameter and the local supporting range in the moving least square approach and the convergence of the nodal resolution are carried out by using some benchmark problems. This method is further verified by applying it to a steady-state convectiondiffusion problem. Finally, the present method is applied to calculate the velocity fields of two potential flow problems. More accurate numerical results are obtained.
356N.-J. WU AND T.-K. TSAY methods, in which governing equations are satisfied automatically in the entire domain, are more applicable to problems in which accurate partial derivatives of the solutions around the boundaries are desirable. Typical examples are the application of method of fundamental solutions to water wave problems [18][19][20]. Nevertheless, boundary-type RBF collocation methods are limited to problems governed by some specific equations, such as Laplace or Helmholtz equations. In [21], a modified domain-type RBF collocation method was proposed. With additional satisfaction to the governing equation on boundary collocation points, the gradient of the velocity potential at any free surface node, which represents the velocity vector at that specific node, was accurately estimated. Thus, this method was successfully applied to the simulation of water waves in a swaying tank.Apart from the combination of RBFs, one could use a polynomial to approximate the solution of a PDE and seek the coefficients of all the monomials by applying the collocation technique. However, polynomials have been rarely used globally such as the basis functions being treated in RBF collocation methods. This is because the values of high-order terms could become extremely large at points far from the origin. In most polynomial collocation methods, polynomials are just applied to approximate the solution piecewise around discretized nodes. The moving least square (MLS) approach is always accompanied with the polynomial approximation to transform and combine the local solutions into a global solution form. In each local solution, basis functions are the monomials, and their factors are just the coefficients. In the global solution form, the basis functions are called the shape functions, and their factors are the values of the solution itself. This localizing approach is somewhat like localized RBF collocation methods [22]. Representatives of this family are the hp-meshless cloud method [23] and the finite point method (FPM) [24,25].Being strong-form methods, polynomial collocation methods with MLS approach are reported to ...