Parallel CFD Simulations of Multiphase Systems: Jet into a Cylindrical Bath and Rotary Drum on a Rectangular Bath.

Most of the developed commercial CFD (Computational Fluid Dynamics) packages do
not attempt to document (or don’t want to publish !!) the detailed algorithm for parallelising
the code; even the ordinary solution strategies are tedious to learn sometimes. However,
industrial engineers are more concerned about quick and correct solutions of their problems.
Key features of this paper are the use of the domain decomposition and encapsulated message
passing to enable execution in parallel. A parallel version of a CFD code, FLUENT, has been
applied to model some multiphase systems on a number of different platforms. The same
models considered for all the platforms to compare the parallel efficiency of CFD in those
machines. Two physical models: one is a liquid jet directed into a cylindrical bath to disperse
buoyant particles suspended on the top of the bath (3D), and the second one is a rotary drum
rotating on a free surface to drag down particles from the free surface. The free surface, high
gradient of the velocity, particle-particle, particle-wall collisions make most industrial flow
simulations computationally expensive. For many complex systems, like here, the
computational resources required limit the detail modelling of CFD. The implementations of
computational fluid dynamics codes on distributed memory architectures are discussed and
analyzed for scalability. For commercial CFD packages, in many cases the solution
algorithms are black boxes, even though parallel computing helps in many cases to overcome
the limitations, as shown here. The performance of the code has been compared in terms of
CPU, accuracy, speed etc. In short, this research is intended to establish a strategic procedure
to optimize a parallel version of a CFD package, FLUENT. The parallelised CFD code shows
the excellent efficiency and scalability on a large number of platforms.