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. UnTRIM parallelization with message passing, 3rd UnTRIM Workshop, Trento, 15-17 May 2006.
This is a second part of the UnTRIM parallelisation project presentations — for the background, see the previous post. The most important issue addressed so far concerns absolving a number of stringent verification tests applied for checking the parallel implementation correctness as well as the user steering of the model. Continue reading →
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 →
Ein nicht-hydrostatisches Modell für Strömungen mit freier Oberfläche, Promotionsvortrag, 12. November 1998, Institut für Strömungsmechanik und Elektronisches Rechnen im Bauwesen der Universität Hannover. Continue reading →