Impact and Ricochet of a High Speed Projectile from a Plate

A computational study of a projectile (either 2024 aluminum or TiAl6V4 titanium alloy) impacting a plate (either titanium alloy or aluminum) is presented in this paper. Projectile velocity (ranging from 250 m/s to 1500 m/s) with varying impact angles are considered. The presence of ricochet (if any) is identified over the ranges of the projectile velocity and impact angle considered. For the cases where ricochet is identified, the ricochet angle and velocity are predicted as functions of the incident angle and the incident velocity. The numerical results are compared with an analytical solution of the ricochet problem. The analytical solutions are from a model developed to predict the ballistic ricochet of a projectile (projectile) penetrator. The dynamics and the deformation of an aluminum (or a titanium alloy) projectile impacting on a finite thickness titanium alloy (or aluminum) plate are simulated. The current work is interesting in that it looks in the field of ballistics of different material combinations than are traditionally studied. The present simulations based on detailed material models for the aluminum and the titanium alloy and the impact physics modelling features in the LS-DYNA code provide interesting details regarding the projectile/plate deformations and post-impact projectile shape and geometry. The present results indicate that for no cases (for specified incoming velocities and impact angles considered) can an aluminum projectile penetrate a titanium alloy plate. The ricochet ‘mode predictions ‘obtained from the present simulations agree well with the ricochet ‘mode predictions’ given in an analytical model

A computational fluid dynamics approach for optimization of a sensor network

Presented at the 2006 IEEE International Workshop on Measurement Systems for Homeland Security, Contraband Detection and Personal Safety. Alexandria, VA.We optimize the placement of sensors for detecting a nuclear, biological, or chemical (NBC) attack in a dense urban environment. This approach draws from two main areas: (1) computational fluid dynamic (CFD) simulations and (2) sensor placement algorithms. The main objective was to minimize detection time of a NBC sensor network for attacks on a generic urban environment. To this end we conducted simulations in the generic urban environment using thirty-three (33) unique attack locations, thirty-three (33) candidate sensor locations, prevailing wind conditions, and the properties of the chemical agent, chlorine gas. A total of ninety-nine (99) simulated attack scenarios were created (three sets of thirty-three unique attack simulations) and used for optimization. Simulated surrogate agent concentration data were collected at each candidate sensor location as a function of time. The integration of this concentration data with respect to time was used to calculate the ”consumption” of the network and the sensor placement algorithm minimized consumption to the network while minimizing the number of sensors placed. Our results show how a small number of properly placed sensors (eight(8), in our case) provides the best achievable coverage (additional sensors do not help)

SIMULATION OF CONTAMINANT DISPERSAL IN AN APARTMENT BUILDING

ABSTRACT Bio-terrorism events (like the 2001 anthrax attacks) accentuate the importance of countering these incidents. In order to develop reliable countermeasures for these events, it is essential to understand the associated transport processes. The transport processes involved pose challenges as they occur over wide ranges of spatial and temporal scales. CONTAMW, a multi zone indoor air quality and ventilation analysis program is used to predict the contaminant dispersal in an apartment building. Detailed simulation results and analysis of controlled release of propylene within a generic apartment building is presented. A zonal analysis is carried out for the entire apartment building (using CONTAMW) to obtain time histories of propylene concentration in different zones. The simulations provide the dispersion, transport and contaminant concentration within each zone of the apartment. This study also considers the effect of flow obstructions and ventilation rates on contaminant dispersal. The results are validated with the experimental results reported in . We have also simulated propylene transport in the apartment with FDS, a large eddy simulation model

Computational fluid dynamics analysis of the effects of reactor configuration on disinfection efficiency

Water Environment Research, 78(9): pp. 909-919, DOI: http://dx.doi.org/10.2175/106143005X72984The efficacy of disinfection processes in water purification systems is governed by several key factors, including reactor hydraulics, disinfectant chemistry, and microbial inactivation kinetics. The objective of this work was to develop a computational fluid dynamics (CFD) model to predict velocity fields, mass transport, chlorine decay, and microbial inactivation in a continuous flow reactor. The CFD model was also used to evaluate disinfection efficiency in alternative reactor designs. The CFD reactor analysis demonstrates that disinfection efficiency is affected by both kinetics and mixing state (i.e., degree of micromixing or segregation). Residence time distributions (RTDs) derived from tracer analysis do not describe intrinsic mixing conditions. The CFD-based disinfection models account for reactor mixing patterns by resolution of the reactor velocity field and thus provide a better prediction of microbial inactivation than models that use an RTD. Water Environ. Res., 78, 909 (2006)

Process, Structure, and Properties of Electrospun Carbon Nanotube-Reinforced Nanocomposite Yarns

Carbon nanotubes (CNTs) are dispersed into polyacrylonitrile polymer solution and then assembled into continuous nanocomposite yarns through the drum-tape co-electrospinning process to facilitate the translation of CNT properties to higher order structures. We explore the dispersion of CNTs in a polymer matrix, the process of obtaining continuous yarn through electrospinning, and the surface morphology and mechanical properties of the nanocomposite yarn