Stochastic Higher-Order Generalized Perturbation Theory for Neutron Diffusion and Transport Calculations

2013 ◽  
Author(s):  
Congjian Wang ◽  
Hany S. Abdel-Khalik
Keyword(s):  
Perturbation Theory ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Scientific Computing ◽  
Nuclear Reactor ◽  
Higher Order ◽  
Engineering Systems ◽  
Current State ◽  
Generalized Perturbation Theory ◽  
Complex Engineering

The role of scientific computing has been heavily promoted in many fields to improve understanding the physics of complex engineering systems in recent years while conduct the experiments can be time-consuming, inflexible, expensive and difficult to repeat, e.g. nuclear reactor systems. The ultimate goal of scientific computing is to provide more reliable predictions for engineering systems within certain acceptable tolerance. To realize the benefits of scientific computing, extensive effort has been devoted to the development of efficient algorithms for Sensitivity Analysis (SA) and Uncertainty Quantification (UQ) whose numerical errors is under control and understood. However, the repeated execution of the simulations with different samples is computationally intractable for large-scale system with large number of Degrees of Freedom (DOF). The object of this manuscript will be focus on presenting our own developments of stochastic higher-order generalized perturbation theory to address the explosion in the computational load burden. Additionally, an overview of the current state-of-the-art of SA/UQ will also be provided.

scholarly journals Understanding design change propagation in complex engineering systems using a digital twin and design structure matrix

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Long Chen ◽  
Jennifer Whyte
Keyword(s):  
Large Scale ◽  
Load Capacity ◽  
Prediction Method ◽  
Change Propagation ◽  
Engineering Systems ◽  
Content Type ◽  
Design Change ◽  
Digital Twin ◽  
Complex Engineering ◽  
Complex Engineering Systems

PurposeAs the engineering design process becomes increasingly complex, multidisciplinary teams need to work together, integrating diverse expertise across a range of disciplinary models. Where changes arise, these design teams often find it difficult to handle these design changes due to the complexity and interdependencies inherent in engineering systems. This paper aims to develop an innovative approach to clarifying system interdependencies and predicting the design change propagation at the asset level in complex engineering systems based on the digital-twin-driven design structure matrix (DSM).Design/methodology/approachThe paper first defines the digital-twin-driven DSM in terms of elements and interdependencies, where the authors have defined three types of interdependency, namely, geospatial, physical and logical, at the asset level. The digital twin model was then used to generate the large-scale DSMs of complex engineering systems. The cluster analysis was further conducted based on the improved Idicula–Gutierrez–Thebeau algorithm (IGTA-Plus) to decompose such DSMs into modules for the convenience and efficiency of predicting design change propagation. Finally, a design change propagation prediction method based on the digital-twin-driven DSM has been developed by integrating the change prediction method (CPM), a load-capacity model and fuzzy linguistics. A section of an infrastructure mega-project in London was selected as a case study to illustrate and validate the developed approach.FindingsThe digital-twin-driven DSM has been formally defined by the spatial algebra and Industry Foundation Classes (IFC) schema. Based on the definitions, an innovative approach has been further developed to (1) automatically generate a digital-twin-driven DSM through the use of IFC files, (2) to decompose these large-scale DSMs into modules through the use of IGTA-Plus and (3) predict the design change propagation by integrating a digital-twin-driven DSM, CPM, a load-capacity model and fuzzy linguistics. From the case study, the results showed that the developed approach can help designers to predict and manage design changes quantitatively and conveniently.Originality/valueThis research contributes to a new perspective of the DSM and digital twin for design change management and can be beneficial to assist designers in making reasonable decisions when changing the designs of complex engineering systems.

scholarly journals Review of Available Data for Validation of Nuresim Two-Phase CFD Software Applied to CHF Investigations

2009 ◽  
Vol 2009 ◽  
pp. 1-14 ◽  
Author(s):  
D. Bestion ◽  
H. Anglart ◽  
D. Caraghiaur ◽  
P. Péturaud ◽  
B. Smith ◽  
...  
Keyword(s):  
Large Scale ◽  
Nuclear Reactor ◽  
Two Phase ◽  
Simulation Tools ◽  
Current State ◽  
Flow Processes ◽  
Reactor Assembly ◽  
Boiling Flow ◽  
Dry Out ◽  
New Generation

The NURESIM Project of the 6th European Framework Program initiated the development of a new-generation common European Standard Software Platform for nuclear reactor simulation. The thermal-hydraulic subproject aims at improving the understanding and the predictive capabilities of the simulation tools for key two-phase flow thermal-hydraulic processes such as the critical heat flux (CHF). As part of a multi-scale analysis of reactor thermal-hydraulics, a two-phase CFD tool is developed to allow zooming on local processes. Current industrial methods for CHF mainly use the sub-channel analysis and empirical CHF correlations based on large scale experiments having the real geometry of a reactor assembly. Two-phase CFD is used here for understanding some boiling flow processes, for helping new fuel assembly design, and for developing better CHF predictions in both PWR and BWR. This paper presents a review of experimental data which can be used for validation of the two-phase CFD application to CHF investigations. The phenomenology of DNB and Dry-Out are detailed identifying all basic flow processes which require a specific modeling in CFD tool. The resulting modeling program of work is given and the current state-of-the-art of the modeling within the NURESIM project is presented.

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