A Computational Fluid Dynamics approach for air blast propagation using OpenFOAM and Becker-Kistiakowsky-Wilson equation of state

Abstract

In this investigation, the shockwave propagation caused by the explosive detonation in a complex environment has been studied by the open-source Computational Fluid Dynamics (CFD) package, OpenFOAM®. An extended solver was developed to take the effect of explosion energy into account. The Becker-Kistiakowsky-Wilson (BKW) equation of state (EOS) was implemented in OpenFOAM® to calculate the detonation impact on the surrounding fluid density variations. Also, the influence of two turbulence modeling approaches of Reynolds-averaged Navier-Stokes (RANS) and Large-eddy Simulation (LES) on the prediction of explosion pressure was studied and compared against previous experimental and numerical studies. The comparisons demonstrated the accuracy of the implemented BKW EOS in calculating the fluid density. Further, it was shown that the LES approach is capable of capturing the unsteady nature of detonation in the near-field of the explosive. Examining the instantaneous velocity vectors of the LES results revealed sequential wave fronts that were responsible for rapid changes in the pressure signals. Furthermore, ground pressure contours demonstrated that the shock waves spread on the ground in a circular shape. The results of the current study suggested that the OpenFOAM® technology is powerful to incorporate various physical models, including the equation of state and scale-resolving methods such as LES, to capture the complex nature of the detonation phenomenon.

Keywords

• sonicFoam
• Equation of state
• Source term
• Blast
• Numerical simulation