A Framework for Implementing Predictive-CFD Capability in a Design-by-Simulation Environment

Computational fluid dynamics (CFD) tools are becoming more widely used in thermal-hydraulic (T/H) and plant analyses due to advances in computational capability, data storage, and speed. However, to date, most CFD studies are ad hoc in nature with little emphasis on building links between and among CFD studies and CFD users. Thus, CFD codes have not yet been effectively leveraged as design tools within the T/H and nuclear applications communities due to lack of a comprehensive and rigorous approach to both verification and validation and uncertainty propagation. Consequentially, CFD is generally relegated to limited diagnostic use or as an adjunct to conventional lumped-parameter codes that often are based on limited testing and use conservative bounding factors applied to the needed design calculations.

Because significant technical progress and development of CFD have occurred over the last decade, the potential now exists to move the use of CFD into the mainstream of analysis tools to address design, operational, and regulatory issues for complex hydraulic systems. This potential can serve as a basis upon which to develop CFD for use in an integrated design-by-simulation (IDS) environment. The CFD methodology to provide this rigor is identified as predictive-CFD (P-CFD) in this technical note.

In the P-CFD/IDS methodology, synergy and consensus will be obtained through more rigorous validation of the underlying physics phenomena of each analysis objective through use of an extensive database of validation-level tests (VLTs) by many universities and laboratories. This approach logically suggests the creation of a national P-CFD database to contain these VLT data sets for general practitioner access. Thus, the underlying physics is a building block for multiple system objectives whose phenomena require those physics behaviors for the needed assessments. By using the P-CFD/IDS methodology, CFD methods can be made consistent, credible, and reproducible.

Extensive references have been included to provide the status of the underlying background that supports P-CFD/IDS development. The path outlined is fully practical but difficult. This technical note is written to show a framework by which a validated CFD study for a given hydraulic objective can be prepared and used for the analyses of complex hydraulic systems to support design conclusions.