Parallel Simulations Of Flow Around High-Aspect Ratio Cylinders Employing Mpi.

Abstract

In this paper, the dynamic response of a long circular cylinder due to vortex shedding is
numerically investigated. The cylinder with high aspect ratio has the structural properties typical of
marine risers. The cylinder is divided in two-dimensional sections along the riser length. The Discrete
Vortex Method (DVM) is employed for the assessment of the hydrodynamic forces acting on these
two-dimensional sections. The hydrodynamic sections are solved independently, and the coupling
among the sections is taken into account by the solution of the structure in the time domain by the
Finite Element Method. Parallel processing is employed to improve the performance of the method.
The simulations are carried out in a cluster of Pentium IV computers running the Linux operating
system. A master-slave approach via MPI – Message Passing Interface – is used to exploit the
parallelism of the present code. The riser sections are equally divided among the nodes of the cluster.
Each node solves the hydrodynamic sections assigned to it. The forces acting on the sections are then
passed to the master processor, which is responsible for the calculation of the displacement of the
whole structure. Scalability of the algorithm is shown and discussed.