Christophe Kassiotis

Unified semi-analytical wall boundary conditions in SPH: analytical extension to 3-D

Solid wall boundary conditions have been an area of active research within the context of Smoothed Particle Hydrodynamics (SPH) for quite a while. Ferrand et al. (Int. J. Numer. Methods Fluids 71(4), 446–472, 2012) presented a novel approach using a renormalization factor in the SPH approximation. The computation of this factor depends on an integral along the boundary of the domain and in their original paper Ferrand et al. gave an analytical formulation for the 2-D case using the Wendland kernel. In this paper the formulation will be extended to 3-D, again providing analytical formulae. Due to the boundary being two dimensional a domain decomposition algorithm needs to be employed in order to obtain special integration domains. For these the analytical formulae will be presented when using the Wendland kernel. The algorithm presented within this paper is applied to several academic test-cases for which either analytical results or simulations with other methods are available. It will be shown that the present formulation produces accurate results and provides a significant improvement compared to approximative methods.

Code-coupling strategy for efficient development of computer software in multiscale and multiphysics nonlinear evolution problems in computational mechanics

Abstract In this work we seek to provide an efficient approach to development of software computational platform for the currently very active research domain of multiphysics and multiscale analysis in fully nonlinear setting. The typical problem to be solved is nonlinear evolution problem, with different scales in space and time. We show here that a successful solution to such a problem requires gathering the sound theoretical formulation, the most appropriate discrete approximation and the efficient numerical implementation. We show in particular that the most efficient numerical implementation is obtained by reusing the existing codes, in order to accelerate the code development and validation. The key element that makes such an approach possible is the Component Template Library (CTL), presented in this work. We show that the CTL allows to seamlessly merge the existing software products into a single code at compilation time, regardless of their ‘heterogeneities’ in terms of programming language or redundancy in use of local variables. A couple of illustrative problems of fluid–structure interaction and multiscale nonlinear analysis are presented in order to confirm the advantage of the proposed approach.