Publications

Results 77376–77400 of 96,771

Search results

Jump to search filters

Peridynamics with LAMMPS : a user guide

Parks, Michael L.; Plimpton, Steven J.; Lehoucq, Richard B.; Silling, Stewart A.

Peridynamics is a nonlocal formulation of continuum mechanics. The discrete peridynamic model has the same computational structure as a molecular dynamic model. This document details the implementation of a discrete peridynamic model within the LAMMPS molecular dynamic code. This document provides a brief overview of the peridynamic model of a continuum, then discusses how the peridynamic model is discretized, and overviews the LAMMPS implementation. A nontrivial example problem is also included.

More Details
TYPE SAND Report YEAR 2008
DOIOSTI

Solute Mixing Models for Water-Distribution Pipe Networks

Journal of Hydraulic Engineering

Ho, Clifford K.

The spreading of solutes or contaminants through water-distribution pipe networks is controlled largely by mixing at pipe junctions where varying flow rates and concentrations can enter the junction. Alternative models of solute mixing within these pipe junctions are presented in this paper. Simple complete-mixing models are discussed along with rigorous computational-fluid-dynamics models based on turbulent Navier-Stokes equations. In addition, a new model that describes the bulk-mixing behavior resulting from different flow rates entering and leaving the junction is developed in this paper. Comparisons with experimental data have confirmed that this bulk-mixing model provides a lower bound to the amount of mixing that can occur within a pipe junction, while the complete-mixing model yields an upper bound. In addition, a simple scaling parameter is used to estimate the actual (intermediate) mixing behavior based on the bounding predictions of the complete-mixing and bulk-mixing models. These simple analytical models can be readily implemented into network-scale models to develop predictions and bounding scenarios of solute transport and water quality in water-distribution systems.

More Details
TYPE Journal Article YEAR 2008
DOIOSTIScopus

Design and performance of a high-repetition-rate single-frequency Yb:YAG microlaser

Schmitt, Randal L.

We describe the design and performance of a high-repetition-rate single-frequency passively Q-switched Yb:YAG microlaser operating near 1030 nm. By using short cavity length, an intracavity Brewster polarizer, and an etalon output coupler, we are able to produce {approx}1-ns-long single-frequency pulses at repetition rates up to 19 kHz without shot-to-shot mode hopping. The laser's output spatial mode is TEM{sub 00} and its pulse energy varies between 31 {micro}J and 47 {micro}J depending on repetition rate. Its peak optical-to-optical efficiency is 22%.

More Details
TYPE Conference YEAR 2008
OSTI
Results 77376–77400 of 96,771
Results 77376–77400 of 96,771