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A conformal decomposition finite element method for material death

ASME 2012 Heat Transfer Summer Conf. Collocated with the ASME 2012 Fluids Engineering Div. Summer Meeting and the ASME 2012 10th Int. Conf. on Nanochannels, Microchannels and Minichannels, HT 2012

Noble, David R.

A Conformal Decomposition Finite Element Method (CDFEM) is developed for modeling material death. Material death is used to model the continuous removal of material that exceeds a prescribed temperature. CDFEM allows for the moving front to move through the material without having to conform to the finite element geometry. The method is tested using 2-dimensional simulations of a 1-dimensional problem with an analytical solution. CDFEM is shown to be optimal for the chosen discretization with first order convergence in time and second order convergence in space. In comparison, a traditional element death algorithm does not converge at all on unstructured meshes. A correction is proposed for remedying this problem, resulting in first order convergence for traditional element death in space and time. Copyright © 2012 by ASME.

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TYPE Conference YEAR 2012
OSTIScopus

Toward application of conformal decomposition finite elements to non-colloidal particle suspensions

International Journal for Numerical Methods in Fluids

Lechman, Jeremy B.; Nemer, Martin; Noble, David R.

Particle suspensions play an important role in many engineering applications, yet their behavior in a number of respects remains poorly understood. In conjunction with careful experiments, modeling and simulation of these systems can provide key insight into their complex behavior. However, these two-phase systems pose the challenge of simultaneously, accurately, and efficiently capturing the complex geometric structure, kinematics, and dynamics of the particulate discrete phase and the discontinuities it introduces into the variables (e.g., velocity, pressure, density) of the continuous phase. To this end, a new conformal decomposition finite element method (CDFEM) is introduced for solid particles in a viscous fluid. The method is verified in several simple test problems that are representative of aspects of particle suspension behavior. In all cases, we find the CDFEM to perform accurately and efficiently leading to the conclusion that it forms a prime candidate for application to the full direct numerical simulation of particle suspensions. © 2012 John Wiley & Sons, Ltd.

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TYPE Journal Article YEAR 2012
ScopusOSTI

Mesoscale to plant-scale models of nuclear waste reprocessing

Rao, Rekha R.; Pawlowski, Roger; Brotherton, Christopher M.; Cipiti, Benjamin B.; Domino, Stefan P.; Jove-Colon, Carlos F.; Moffat, Harry K.; Nemer, Martin; Noble, David R.; O'Hern, Timothy J.

Imported oil exacerabates our trade deficit and funds anti-American regimes. Nuclear Energy (NE) is a demonstrated technology with high efficiency. NE's two biggest political detriments are possible accidents and nuclear waste disposal. For NE policy, proliferation is the biggest obstacle. Nuclear waste can be reduced through reprocessing, where fuel rods are separated into various streams, some of which can be reused in reactors. Current process developed in the 1950s is dirty and expensive, U/Pu separation is the most critical. Fuel rods are sheared and dissolved in acid to extract fissile material in a centrifugal contactor. Plants have many contacts in series with other separations. We have taken a science and simulation-based approach to develop a modern reprocessing plant. Models of reprocessing plants are needed to support nuclear materials accountancy, nonproliferation, plant design, and plant scale-up.

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TYPE Conference YEAR 2010
OSTI
Results 126–150 of 195
Results 126–150 of 195