ASTRID - Accompagnement Spécifique de Travaux de Recherches et d'Innovation Défense

Simulation of Detonation Wave Mitigation by Aqueous Foams – SIMATOD

Limit the devastating effects of explosive terrorist

English deminers have realized, in Ireland in the 1970s, as the foam used by firefighters could mitigate the blast effects of explosives advantageously replacing sandbags commonly used.

Model the interaction of a detonation wave with the foam

To properly size the aqueous foam, it seems essential to simulate the propagation of the detonation wave in this medium. This is a biphasic medium as though mainly consisting of air and fine water droplets, the water evaporates under the effect of heat due to the shock wave. It is therefore both to model such complex flows strongly, taking into account the technological constraints and to design a tool for field use.

We will implement multi-fluid models with kinematic imbalance between phases in particular. The main innovation of the project is to develop a simulation platform that relies on both a full model relevant to the physics involved (detonation model and two-fluid model with phase change) and that is powerful the industrial point of view (reasonable computation time on a standard PC).

NOT APPLICABLE at this stage of the project

This project will optimize the containment of improvised explosive with a tent which allows, in particular in the case of dirty bombs, limit the consequences for the environment.

NOT APPLICABLE at this stage of the project

The project SIMATOD aims at the design of a robust numerical tool for the simulation of shock waves propagation in aqueous foams which goal is to evaluate the mitigating effect of such foams after a detonating blast.
The design of such a simulation tool is motivated by the use, in many situations, of aqueous foams to mitigate the pressure loading produced by the detonation of high explosives. Interestingly enough, the foam retains also the products of the chemical reactions which produce the blast wave preventing poisons to disseminate in the atmosphere.

Mitigation of blast waves by aqueous foams is an important technological issue. Despite many theoretical and experimental advances on the subject it has not been possible, up to now, to have simple analytical expressions or abacus providing the pressure as a function of the distance to the charge, its strength and of the characteristic of the foam.
In this context, numerical simulation ought to be tried as a relevant tool to obtain the desired results. Yet, the flow in aqueous foams is complex as 3 fluids (air, steam and water) and phase transitions are involved and, moreover, the geometry of the free surfaces between these fluids is quite complicated.
The ambition of the project is to set the path for a robust industrial code to handle these critical issues. We ought to rely on a classical averaged model for multi-fluid flow, which allows bypassing the local geometrical complexity of the flow at the cost of new variables such as the volumetric rate of presence of each fluid.
Moreover, since our goal is to simulate blast waves from a point, we shall safely assume that the flow has the spherical symmetry. Hence models will be 1D.
The state of the art to our knowledge does not allow overcoming the theoretical difficulties that remain. This project ought to address this challenge. A robust simulation tool in this domain provides a real opportunity to develop a dual technology that will unlock several civil markets. The presence of Eurobios in this consortium will allow leveraging efficiently the work that will be achieved thanks to its scientific software edition expertise and know how.

Project coordinator

Monsieur Jean-Michel GHIDAGLIA (ECOLE NORMALE SUPERIEURE DE CACHAN) – jmg@cmla.ens-cachan.fr

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

EUROBIOS EUROBIOS
CMLA ECOLE NORMALE SUPERIEURE DE CACHAN
UPS/LMO UNIVERSITE DE PARIS XI [PARIS- SUD]

Help of the ANR 293,914 euros
Beginning and duration of the scientific project: November 2011 - 24 Months

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