Jacek A. Jankowski. Further developments of UnTRIM: parallel implementation and its verification, ISEH V – IAHR Fifth International Symposium on Environmental Hydraulics, 2007, Tempe, Arizona, USA.
This presentation is complementary to the contributed conference paper. It is a summary of all stages of the development of the parallel version of UnTRIM applying the domain decomposition method and message passing (MPI): Continue reading
J.A. Jankowski
Abstract. This contribution deals with further developments of UnTRIM, an unstructured-grid, three-dimensional, semi-implicit finite difference finite volume model for the shallow water equations (Casulli, 2002). Attractive numerical properties of the method like its robustness due to the unlimited stability and successes in practical applications spawned efforts aimed at making the available code fit for the high performance computing in order to address larger, complex problems in hydraulic engineering. Continue reading
Jacek A. Jankowski. Parallel streamline tracking for UnTRIM, 4th UnTRIM Workshop, Trento, 7-9 May 2007.
The parallel streamline tracking algorithm for the domain decomposition method applied in the MPI version of UnTRIM, is described in detail. The streamline tracking is the integral part of the semi-Lagrangian method of characteristics, being one of the most robust methods for the non-linear momentum advection, working also for larger Courant numbers. The method is however awkward to parallelise in the framework of the point-to-point communication typical for the domain decomposition method. Continue reading
Jacek A. Jankowski and Andreas Malcherek.
Developing an advection scheme for Telemac-2D based on the 2nd order characteristics method, 8th Telemac User Club, Chatou, 15-16 November 2001.
One of the best method of improving the accuracy of the advection scheme based on method of characterictics is to improve the interpolation of advected variables on the feet of the traced-back characteristic curves. The results of applying the second order interpolation in broader element patches are compared with the presently applied single-element linear interpolation and the SUPG method. Continue reading
Jacek A. Jankowski
PhD thesis Abstract
An algorithm for solution of three-dimensional Navier-Stokes equations for incompressible free surface flows is developed. A decoupled algorithm based on the fractional step (operator-splitting) technique is applied. The solution is obtained in subsequent stages treating equations split into parts having well-defined mathematical properties, so that the most adequate methods for a given differential operator type can be used. The decoupled algorithm structure, which does not use the continuity equation explicitly, allows application of equal-order linear interpolation functions for all variables. The applied reference element type, a prism with six nodes and linear interpolation functions, is a compromise between the exactness of the interpolation, model complexity and computational cost. The finite difference method is applied for the time discretisation and the computational domain variability is taken into account by a standard sigma-mesh structure which is well suited to most geophysical applications. Continue reading