Publications

Results 151–175 of 193

Search results

Jump to search filters

Thermal hydraulic simulations, error estimation and parameter sensitivity studies in Drekar::CFD

Shadid, John N.; Pawlowski, Roger P.; Cyr, Eric C.; Wildey, Timothy M.

This report describes work directed towards completion of the Thermal Hydraulics Methods (THM) CFD Level 3 Milestone THM.CFD.P7.05 for the Consortium for Advanced Simulation of Light Water Reactors (CASL) Nuclear Hub effort. The focus of this milestone was to demonstrate the thermal hydraulics and adjoint based error estimation and parameter sensitivity capabilities in the CFD code called Drekar::CFD. This milestone builds upon the capabilities demonstrated in three earlier milestones; THM.CFD.P4.02 [12], completed March, 31, 2012, THM.CFD.P5.01 [15] completed June 30, 2012 and THM.CFD.P5.01 [11] completed on October 31, 2012.

More Details
TYPE SAND Report YEAR 2014
DOIOSTI

Enhancing least-squares finite element methods through a quantity-of-interest

SIAM Journal on Numerical Analysis

Cyr, Eric C.; Chaudhry, Jehanzeb H.; Liu, Kuo; Manteuffel, Thomas A.; Olson, Luke N.; Tang, Lei

In this paper we introduce an approach that augments least-squares finite element formulations with user-specified quantities-of-interest. The method incorporates the quantity-ofinterest into the least-squares functional and inherits the global approximation properties of the standard formulation as well as increased resolution of the quantity-of-interest. We establish theoretical properties such as optimality and enhanced convergence under a set of general assumptions. Central to the approach is that it offers an element-level estimate of the error in the quantity-ofinterest. As a result, we introduce an adaptive approach that yields efficient, adaptively refined approximations. Several numerical experiments for a range of situations are presented to support the theory and highlight the effectiveness of our methodology. Notably, the results show that the new approach is effective at improving the accuracy per total computational cost.

More Details
TYPE Journal Article YEAR 2014
DOIDOIOSTIScopusOSTIScopus

Spatially varying embedded stochastic galerkin methods for steady-state PDEs

Cyr, Eric C.

Existing discretizations for stochastic PDEs, based on a tensor product between the deterministic basis and the stochastic basis, treat the required resolution of uncertainty as uniform across the physical domain. However, solutions to many PDEs of interest exhibit spatially localized features that may result in uncertainty being severely over or under-resolved by existing discretizations. In this report, we explore the mechanics and accuracy of using a spatially varying stochastic expansion. This is achieved through an adaptive refinement algorithm where simple error estimates are used to independently drive refinement of the stochastic basis at each point in the physical domain. Results are presented comparing the accuracy of the adaptive techinque to the accuracy achieved using uniform refinement.

More Details
TYPE SAND Report YEAR 2013
DOIOSTI

A comparison of adjoint and data-centric verification techniques

Cyr, Eric C.; Shadid, John N.; Smith, Thomas M.; Pawlowski, Roger P.

This document summarizes the results from a level 3 milestone study within the CASL VUQ effort. We compare the adjoint-based a posteriori error estimation approach with a recent variant of a data-centric verification technique. We provide a brief overview of each technique and then we discuss their relative advantages and disadvantages. We use Drekar::CFD to produce numerical results for steady-state Navier Stokes and SARANS approximations. 3

More Details
TYPE SAND Report YEAR 2013
DOIOSTI
Results 151–175 of 193
Results 151–175 of 193