Development of Physical Models and Improved Usability for the APOLLO Blastsimulator Software
Abstract
The APOLLO Blastsimulator is a specialized CFD tool dedicated to the simulation of explosions, blast waves and gas dynamics. It is being developed and exclusively owned by Fraunhofer EMI, located in Freiburg, Germany. The APOLLO Blastsimulator software is licensed to AFRL, DSTL (UK) and several other military related, governmental organisations in Europe. The main purpose of the software is the computation of transient flow fields and pressures generated by detonations of high explosives. This is achieved by numerical integration of the fluid dynamic conservation equations and further physical models related to the thermodynamics of the involved materials. The models and methods used in the software have been selected and developed to enable computationally efficient and accurate simulations of explosive events; the software has been endowed with a range of useful options for typical engineering analysis. The current proposal aims to further develop the physical models in APOLLO towards explosively generated flow fields with additional reactive particle phases. Reactive particles addressed here are mainly the aluminium particles contained in some high explosives which enhance temperatures and impulses through heterogeneous afterburning with the gaseous detonation products and air. A further reactive particle phase considered in this proposal is concrete dust generated through impact-perforation processes inside buildings; this concrete dust is believed to interact with the afterburning processes. Modelling and investigation of the effects of concrete dust in explosive flow fields is thus a further objective in this proposal.Another objective addressed in this proposal is the improvement of the usability of the APOLLO Blastsimulator software towards the simulation of multi-charge explosions. This particularly concerns the dynamic mesh adaption (DMA) which is an essential feature of the APOLLO Blastsimulator. DMA provides the automatic adaption of the local mesh resolution to the computed transient flow features (pressure waves, contact surfaces etc.) and thereby enables accurate and efficient simulations. A particular challenge in the simulation of explosions is the changing length scale- initially the characteristic length scale is dominated by the (small) charge size; the length scale however increases as the blast waves evolves until it asymptotically reaches its maximum wave length. In this process the characteristic length scale typically increases by a factor of about 40 (e.g. from about 5 cm to about 200 cm for 1 kg TNT). In order to maintain accuracy and efficiency, the spatial resolution used in the simulation must be adapted to the changing length scale. This is achieved the APOLLO Blastsimulator by the so-called zoom-option. The zoom-option allows to temporarily increase the spatial resolution in a selected, dynamically growing region of the computational domain. This region is centered around the charge and is automatically adapted to the propagating blast wave and the increasing length scale. The-zoom option has been developed for treatment of a single charge and shall now be accommodated for application to multi-charge explosions.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 04, 2023
- Source ID
- FA86552217165
Entities
People
- Arno Klomfass
Organizations
- Air Force Office of Scientific Research
- Fraunhofer Society
- United States Air Force