1
Numerical Modeling of Explosively Loaded Concrete Structure Using a
Coupled CFD-CSD Methodology
Michael E. Giltrud
1
, Joseph D. Baum
2
, Orlando A. Soto
3
, Fumiya Togashi
4
and Rainald Löhner
5
1
Applied Simulations Inc., 10001 Chartwell Manor Ct., Potomac, MD 20854, USA
(mike.giltrud@appliedsimulations.com)
2
Applied Simulations Inc., 10001 Chartwell Manor Ct., Potomac, MD 20854, USA
(joseph.d.baum@appliedsimulations.com)
3
Applied Simulations Inc., 10001 Chartwell Manor Ct., Potomac, MD 20854, USA
(orlando.a.soto@appliedsimulations.com)
4
Applied Simulations Inc., 10001 Chartwell Manor Ct., Potomac, MD 20854, USA
(fumiya.togashi@appliedsimulations.com)
5
George Mason University, Fairfax, VA 22030, USA
(rlohner@gmu.edu)
This paper describes the application of a state-of-the-art coupled computational fluid dynamics
(CFD) and computational structural dynamics (CSD) methodology to the simulation of an explosively
loaded reinforced concrete structure that was loaded to destruction. The objective of the study was to
predict the response of the structure, initial debris launch and pressure response within and external to the
structure for four differing load cases.
The subject of this study was a joint Norwegian and Swedish experimental program, completed in
2008, that examined the detonation of explosives within concrete structures and the lethal debris thrown
out to large distances. This debris can often be the most important hazard parameter following an
accidental detonation. This was the third in a series of such tests and is known as The Kasun-III test series.
The test structures were small reinforced concrete cubes having internal dimensions of 2.0 by 2.0 by 2.0
meters.
Four different load cases consisting of both cased and bare charges were selected to assess the
effectiveness of a coupled CFD-CSD simulation. The simulation must address HE initiation, detonation
wave propagation through the HE, air blast impact on the concrete structure and initial structural response,
subsequent structural failure and debris launch, and propagation of air blast to the far field. Over the last
several years we have developed a numerical methodology that couples state-of-the-art CFD and CSD
methodologies. The flow code solves the time-dependent, compressible Euler and Reynolds-Averaged
Navier-Stokes equations on an unstructured mesh of tetrahedral elements. The CSD code solves explicitly
the large deformation, large strain formulation equations on an unstructured grid composed of bricks and
hexahedral elements. The codes are coupled via a ‘loose coupling’ approach which decouples the CFD and
CSD sets of equations and uses projection methods to transfer interface information between the CFD and
CSD domains.
The results of the simulations generally compare well with the experimental data. The predicted
initial structural disassembly agrees well with the initial high speed photography. The predictions exhibit
similar failure mechanisms, failure locations and times of failure. The far field pressures exhibit similar
decay with range as the experimental data though the pressure is slightly higher. Finally the initial
structural debris launch velocity follows that of the experiment.
Keywords: CFD, CSD, Airblast, Wall Breach, Blast Propagation