# 351.bwaves

SPEC OMP2012 Benchmark Description

## Benchmark Name

351.bwaves

## Benchmark Author

Dr. Mark Kremenetsky, <mdk [at] sgi.com>

Silicon Graphics International Corp.

46600 Landing Parkway

Fremont, CA 94538, USA

## Benchmark Program General Category

Computational Fluid Dynamics

## Benchmark Description

351.bwaves numerically simulates blast waves in three dimensional
transonic transient laminar viscous flow.

The initial configuration
of the blast waves problem consists of a high pressure and density region
at the center of a cubic cell of a periodic lattice, with low pressure
and density elsewhere. Periodic boundary conditions are applied to the
array of cubic cells forming an infinite network. Initially, the high
pressure volume begins to expand in the radial direction as
classical shock waves. At the same time, the expansion waves move to
fill the void at the center of the cubic cell. When the expanding flow
reaches the boundaries, it collides with its periodic images from
other cells, thus creating a complex structure of interfering
nonlinear waves. These processes create a nonlinear damped periodic
system with energy being dissipated in time. Finally, the system will
come to an equilibrium and steady state.

The algorithm implemented is an unfactored solver for the
implicit solution of the compressible Navier-Stokes equations using the biconjugate gradient stabilized (Bi-CGstab)
algorithm, which solves systems of non-symmetric linear equations
iteratively.

## Input Description

The input file describes the grid size, flow parameters, initial
boundary condition and number of time steps. The three data sets,
test, train and ref, differ only in grid size and number of time
steps.

The test case is a 3-D laminar flow with Reynolds Number equal to 1E+05 and Prandtl Number equals to 0.72. In the reference data set, there are 53*64*2048 computational cells in the 1st, 2nd and 3rd dimensions, respectively. The problem is solved using by implicit time-marching scheme with a CFL number equals to 2.

## Output Description

The transient nature of the flow and iterative solver makes bwaves
a difficult problem to validate. In SPEC OMP2012 this has been
addressed by comparing three different outputs. These are:

- The L2 norm of dq(l.i.j.k) vector after final time step
- The residual for convergence after each time step
- The cumulative sum of iterations for convergence for every time step

## Programming Language

Fortran 77

## Known portability issues

none

## References

Mark Kremenetsky, Arthur Raefsky, Steve P. Reinhardt, "Poor Scalability of Parallel Shared Memory Model: Myth or Reality?", in Proceedings of International Conference on Computational Science'2003. pp.657~666
DOI

Last updated: June 20, 2012