Blast Dynamics

Coupled Eulerian-Lagrangian (CEL) simulations are designed and executed in this work to explore the blast wave shielding effect of a porous spatially-periodic wall in the intermediate field of a large-scale explosion. To this aim, the incident peak average overpressure and the average specific positive impulse are determined over virtual planes located at various distances behind rigid walls of different porosity levels. Aresulting manifold of high-cost high-fidelity numerical solutions is then used to devise simplified and more computationally-efficient data-driven surrogate analytical and machine-learning predictive models.

Evaluating the blast loads that structures can be subjected to mainly relies on traditional design manuals that are mostly restricted to free-field explosions or to confined settings of simple geometry. However, the blast loads that apply to structures located in denser environments are significantly affected by the complex interactions of the blast wave with the urban topography. Many existing works address the effects resulting from such interactions; however, their scopes are mostly limited to considering a few buildings or streets, while the influence of building porosity on the shielding effect has received limited attention. This work utilizes validated high-fidelity numerical simulations to carry out a detailed investigation of the influence of a building’s porosity (categorized as “zero”, “low”, “medium” and “high”) on its capacity to shield virtual facades located at several distances behind the shielding structure. The results show that the shielding effect is mainly bounded below by that behind the high-porosity building and above by that behind the zero or low-porosity building, depending on the standoff distance to the charge. Finally, suitable scaling and modeling approaches including regression and machine learning techniques are applied to devise simplified, yet more general data-driven surrogate tools for computationally inexpensive predictions. These can contribute in helping design engineers evaluate blast loads behind porous structures following explosions in cityscapes.