Publications

Robinson, Allen C.; Drake, Richard R.; Carpenter, John H.; Wills, Ann E.; Rider, William J.; Debusschere, Bert D.

Abstract not provided.

Robinson, Allen C.

Computational testing of the arbitrary Lagrangian-Eulerian shock physics code, ALEGRA, is presented using an exact solution that is very similar to a shaped charge jet flow. The solution is a steady, isentropic, subsonic free surface flow with significant compression and release and is provided as a steady state initial condition. There should be no shocks and no entropy production throughout the problem. The purpose of this test problem is to present a detailed and challenging computation in order to provide evidence for algorithmic strengths and weaknesses in ALEGRA which should be examined further. The results of this work are intended to be used to guide future algorithmic improvements in the spirit of test-driven development processes.

Love, Edward L.; Robinson, Allen C.; Ridzal, Denis R.

We review the edge element formulation for describing the kinematics of hyperelastic solids. This approach is used to frame the problem of remapping the inverse deformation gradient for Arbitrary Lagrangian-Eulerian (ALE) simulations of solid dynamics. For hyperelastic materials, the stress state is completely determined by the deformation gradient, so remapping this quantity effectively updates the stress state of the material. A method, inspired by the constrained transport remap in electromagnetics, is reviewed, according to which the zero-curl constraint on the inverse deformation gradient is implicitly satisfied. Open issues related to the accuracy of this approach are identified. An optimization-based approach is implemented to enforce positivity of the determinant of the deformation gradient. The efficacy of this approach is illustrated with numerical examples.

Robinson, Allen C.

Abstract not provided.

Robinson, Allen C.; Petney, Sharon P.; Drake, Richard R.; Weirs, Vincent G.; Adams, Brian M.; Vigil, Dena V.; Carpenter, John H.; Garasi, Christopher J.; Wong, Michael K.; Robbins, Joshua R.; Siefert, Christopher S.; Strack, Otto E.; Wills, Ann E.; Trucano, Timothy G.; Bochev, Pavel B.; Summers, Randall M.; Stewart, James R.; Ober, Curtis C.; Rider, William J.; Haill, Thomas A.; Lemke, Raymond W.; Cochrane, Kyle C.; Desjarlais, Michael P.; Love, Edward L.; Voth, Thomas E.; Mosso, Stewart J.; Niederhaus, John H.

Abstract not provided.

Computers and Fluids

Robinson, Allen C.; Berry, Robert D.; Carpenter, John H.; Debusschere, Bert D.; Drake, Richard R.; Mattsson, A.E.; Rider, William J.

Uncertainty quantification (UQ) deals with providing reasonable estimates of the uncertainties associated with an engineering model and propagating them to final engineering quantities of interest. We present a conceptual UQ framework for the case of shock hydrodynamics with Euler's equations where the uncertainties are assumed to lie principally in the equation of state (EOS). In this paper we consider experimental data as providing both data and an estimate of data uncertainty. We propose a specific Bayesian inference approach for characterizing EOS uncertainty in thermodynamic phase space. We show how this approach provides a natural and efficient methodology for transferring data uncertainty to engineering outputs through an EOS representation that understands and deals consistently with parameter correlations as sensed in the data.Historically, complex multiphase EOSs have been built utilizing tables as the delivery mechanism in order to amortize the cost of creation of the tables over many subsequent continuum scale runs. Once UQ enters into the picture, however, the proper operational paradigm for multiphase tables become much less clear. Using a simple single-phase Mie-Grüneisen model we experiment with several approaches and demonstrate how uncertainty can be represented. We also show how the quality of the tabular representation is of key importance. As a first step, we demonstrate a particular tabular approach for the Mie-Grüneisen model which when extended to multiphase tables should have value for designing a UQ-enabled shock hydrodynamic modeling approach that is not only theoretically sound but also robust, useful, and acceptable to the modeling community. We also propose an approach to separate data uncertainty from modeling error in the EOS. © 2012 Elsevier Ltd.

Carpenter, John H.; Wills, Ann E.; Rider, William J.; Debusschere, Bert D.; Robinson, Allen C.; Drake, Richard R.

Abstract not provided.

Carpenter, John H.; Robinson, Allen C.; Debusschere, Bert D.; Wills, Ann E.; Drake, Richard R.; Rider, William J.

Abstract not provided.

Carpenter, John H.; Wills, Ann E.; Rider, William J.; Debusschere, Bert D.; Robinson, Allen C.; Drake, Richard R.

Abstract not provided.

Carpenter, John H.; Wills, Ann E.; Rider, William J.; Debusschere, Bert D.; Robinson, Allen C.; Drake, Richard R.

Abstract not provided.

Niederhaus, John H.; Robinson, Allen C.

Abstract not provided.

Love, Edward L.; Robinson, Allen C.

Abstract not provided.

Jennings, Christopher A.; Martin, Matthew; Sefkow, Adam B.; Nakhleh, Charles N.; Robinson, Allen C.; Niederhaus, John H.

Abstract not provided.

Carpenter, John H.; Robinson, Allen C.; Rider, William J.; Wills, Ann E.; Debusschere, Bert D.; Drake, Richard R.

Abstract not provided.

Carpenter, John H.; Wills, Ann E.; Rider, William J.; Debusschere, Bert D.; Robinson, Allen C.; Drake, Richard R.

Abstract not provided.

Carpenter, John H.; Robinson, Allen C.; Debusschere, Bert D.; Drake, Richard R.; Wills, Ann E.; Rider, William J.

Abstract not provided.

Carpenter, John H.; Wills, Ann E.; Rider, William J.; Berry, Robert D.; Debusschere, Bert D.; Robinson, Allen C.; Drake, Richard R.

Abstract not provided.

Carpenter, John H.; Wills, Ann E.; Rider, William J.; Berry, Robert D.; Debusschere, Bert D.; Robinson, Allen C.; Drake, Richard R.

Abstract not provided.

Robinson, Allen C.

Abstract not provided.

Robinson, Allen C.; Carpenter, John H.; Drake, Richard R.; Wills, Ann E.; Rider, William J.; Berry, Robert D.; Debusschere, Bert D.

Abstract not provided.

Barrett, Richard F.; Drake, Richard R.; Robinson, Allen C.

Abstract not provided.

Niederhaus, John H.; Garasi, Christopher J.; Robinson, Allen C.

Abstract not provided.

Robinson, Allen C.

Abstract not provided.

Ames, Thomas L.; Robinson, Allen C.

We examine several conducting spheres moving through a magnetic field gradient. An analytical approximation is derived and an experiment is conducted to verify the analytical solution. The experiment is simulated as well to produce a numerical result. Both the low and high magnetic Reynolds number regimes are studied. Deformation of the sphere is noted in the high Reynolds number case. It is suggested that this deformation effect could be useful for designing or enhancing present protection systems against space debris.

Siefert, Christopher S.; Robinson, Allen C.

We describe the implementation of a prototype fully implicit method for solving three-dimensional quasi-steady state magnetic advection-diffusion problems. This method allows us to solve the magnetic advection diffusion equations in an Eulerian frame with a fixed, user-prescribed velocity field. We have verified the correctness of method and implementation on two standard verification problems, the Solberg-White magnetic shear problem and the Perry-Jones-White rotating cylinder problem.