The overall conduct of verification, validation and uncertainty quantification (VVUQ) is discussed through the construction of a workflow relevant to computational modeling including the turbulence problem in the coarse grained simulation (CGS) approach. The workflow contained herein is defined at a high level and constitutes an overview of the activity. Nonetheless, the workflow represents an essential activity in predictive simulation and modeling. VVUQ is complex and necessarily hierarchical in nature. The particular characteristics of VVUQ elements depend upon where the VVUQ activity takes place in the overall hierarchy of physics and models. In this chapter, we focus on the differences between and interplay among validation, calibration and UQ, as well as the difference between UQ and sensitivity analysis. The discussion in this chapter is at a relatively high level and attempts to explain the key issues associated with the overall conduct of VVUQ. The intention is that computational physicists can refer to this chapter for guidance regarding how VVUQ analyses fit into their efforts toward conducting predictive calculations.
This report summarizes the results of a NEAMS project focused on the use of uncertainty and sensitivity analysis methods within the NEK-5000 and Dakota software framework for assessing failure probabilities as part of probabilistic risk assessment. NEK-5000 is a software tool under development at Argonne National Laboratory to perform computational fluid dynamics calculations for applications such as thermohydraulics of nuclear reactor cores. Dakota is a software tool developed at Sandia National Laboratories containing optimization, sensitivity analysis, and uncertainty quantification algorithms. The goal of this work is to demonstrate the use of uncertainty quantification methods in Dakota with NEK-5000.
Prism is a ParaView plugin that simultaneously displays simulation data and material model data. This document describes its capabilities and how to use them. A demonstration of Prism is given in the first section. The second section contains more detailed notes on less obvious behavior. The third and fourth sections are specifically for Alegra and CTH users. They tell how to generate the simulation data and SESAME files and how to handle aspects of Prism use particular to each of these codes.