A least-squares implicit RBF-FD closest point method and applications to PDEs on moving surfaces

Highlights: • In this paper, a novel least-squares approach to stabilize the RBF closest point method is proposed. • The use of RBF-FD allows the construction of higher-order accurate results by increasing the number of points in the stencil. • Convergence is also shown for irregular types of computational tubes in a neighborhood of the surface. • A coupled algorithm for the solution of PDEs on moving surfaces is introduced. • Convergence tests and examples of reaction–diffusion and Cahn–Hilliard systems on moving surfaces are presented. -- Abstract: The closest point method (Ruuth and Merriman (2008) [32]) is an embedding method developed to solve a variety of partial differential equations (PDEs) on smooth surfaces, using a closest point representation of the surface and standard Cartesian grid methods in the embedding space. Recently, a closest point method with explicit time-stepping was proposed that uses finite differences derived from radial basis functions (RBF-FD). Here, we propose a least-squares implicit formulation of the closest point method to impose the constant-along-normal extension of the solution on the surface into the embedding space. Our proposed method is particularly flexible with respect to the choice of the computational grid in the embedding space. In particular, we may compute over a computational tube that contains problematic nodes. This fact enables us to combine the proposed method with the grid based particle method (Leung and Zhao (2009) [37]) to obtain a numerical method for approximating PDEs on moving surfaces. We present a number of examples to illustrate the numerical convergence properties of our proposed method. Experiments for advection–diffusion equations and Cahn–Hilliard equations that are strongly coupled to the velocity of the surface are also presented.