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Canonical and noncanonical Hamiltonian operator inference

Computer Methods in Applied Mechanics and Engineering

Gruber, Anthony D.; Tezaur, Irina K.

Here, a method for the nonintrusive and structure-preserving model reduction of canonical and noncanonical Hamiltonian systems is presented. Based on the idea of operator inference, this technique is provably convergent and reduces to a straightforward linear solve given snapshot data and gray-box knowledge of the system Hamiltonian. Examples involving several hyperbolic partial differential equations show that the proposed method yields reduced models which, in addition to being accurate and stable with respect to the addition of basis modes, preserve conserved quantities well outside the range of their training data.

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TYPE Journal Article YEAR 2023
DOIOSTI

ALEGRA: Finite element modeling for shock hydrodynamics and multiphysics

International Journal of Impact Engineering

Niederhaus, John H.J.; Bova, Steven W.; Carleton, James B.; Carpenter, John H.; Cochrane, Kyle; Crockatt, Michael M.; Dong, Wen; Fuller, Timothy J.; Granzow, Brian N.; Ibanez-Granados, Daniel A.; Kennon, Stephen R.; Luchini, Christopher B.; Moral, Ramon J.; Brien, Michael J.'.; Powell, Michael J.; Robinson, Allen C.; Rodriguez, Angel E.; Sanchez, Jason J.; Scott, Walter A.; Siefert, Christopher; Stagg, Alan K.; Tezaur, Irina K.; Voth, Thomas E.; Wilkes, John R.

ALEGRA is a multiphysics finite-element shock hydrodynamics code, under development at Sandia National Laboratories since 1990. Fully coupled multiphysics capabilities include transient magnetics, magnetohydrodynamics, electromechanics, and radiation transport. Importantly, ALEGRA is used to study hypervelocity impact, pulsed power devices, and radiation effects. The breadth of physics represented in ALEGRA is outlined here, along with simulated results for a selected hypervelocity impact experiment.

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TYPE Journal Article YEAR 2023
DOIOSTI

A Novel Partitioned Approach for Reduced Order Model - Finite Element Model (ROM-FEM) and ROM-ROM Coupling

Earth and Space 2022: Space Exploration, Utilization, Engineering, and Construction in Extreme Environments - Selected Papers from the 18th Biennial International Conference on Engineering, Science, Construction, and Operations in Challenging Environments

De Castro, Amy; Kuberry, Paul; Tezaur, Irina K.; Bochev, Pavel B.

Partitioned methods allow one to build a simulation capability for coupled problems by reusing existing single-component codes. In so doing, partitioned methods can shorten code development and validation times for multiphysics and multiscale applications. In this work, we consider a scenario in which one or more of the “codes” being coupled are projection-based reduced order models (ROMs), introduced to lower the computational cost associated with a particular component. We simulate this scenario by considering a model interface problem that is discretized independently on two non-overlapping subdomains. We then formulate a partitioned scheme for this problem that allows the coupling between a ROM “code” for one of the subdomains with a finite element model (FEM) or ROM “code” for the other subdomain. The ROM “codes” are constructed by performing proper orthogonal decomposition (POD) on a snapshot ensemble to obtain a low-dimensional reduced order basis, followed by a Galerkin projection onto this basis. The ROM and/or FEM “codes” on each subdomain are then coupled using a Lagrange multiplier representing the interface flux. To partition the resulting monolithic problem, we first eliminate the flux through a dual Schur complement. Application of an explicit time integration scheme to the transformed monolithic problem decouples the subdomain equations, allowing their independent solution for the next time step. We show numerical results that demonstrate the proposed method’s efficacy in achieving both ROM-FEM and ROM-ROM coupling.

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TYPE Journal Article YEAR 2023
DOIOSTIScopus
Results 1–25 of 202
Results 1–25 of 202