These slides were presented at the NAFEMS World Congress 2025, held in Salzburg, Austria from May 19–22, 2025.

Abstract

In recent years, simulation has become increasingly important to industrial decision-making. As a result, expectations for simulation credibility have risen significantly. To achieve this goal, appropriate Verification, Validation & Uncertainty Quantification (VVUQ) processes are essential, with validation playing a central role. However, successful implementation of validation faces several challenges. One of the primary issues is the availability of dedicated high-quality experiments that serve as validation referents, in line with recommendations of existing standards. Therefore, a broader range of validation referents needs to be considered in practice, leading to a wide spectrum of validation approaches with varying levels of rigour and credibility. In light of these challenges, the NAFEMS Simulation Governance & Management Working Group (SGMWG) has developed a book titled 'œGuidelines for Validation of Engineering Simulations'. The aim is to provide guidance for industry practitioners, helping them overcome these obstacles and enhance the credibility of their simulation results. It specifically focuses on the validation of physics-based simulation models. NAFEMS has adopted the definition of ISO 9000, and the ISO 9001:2015, 'œQuality management systems, Requirements' [1], which is the basis of the NAFEMS 'œEngineering Simulation Quality Management Standard' (ESQMS) [2]. Other organizations, notably the American Society of Mechanical Engineers (ASME) and their ASME VVUQ standards [3,4], require validation to be based on empirical evidence, i.e. physical experiments. The ISO/NAFEMS definition embeds the more stringent ASME definition as a subset, but allows for a wider range of validation referents, so that the same processes can be applied on applications with varying criticality and credibility requirements. The presentation tackles the above validation challenges and aims to explain the main features of the book. Firstly, it formally introduces the concept of a 'œspectrum of validation methods'. The methods span the range from the strict definition of validation used in the ASME VVUQ standards, through to weaker validation approaches, including those supported by expert review. The introduction of the spectrum of validation methods is purposely high level and may need appropriate tailoring for application to specific industry applications. The second main contribution of the book lies in the formal definition of validation rigour attributes that significantly impact the credibility of simulations. It is recommended to incorporate these rigour attributes during the specification and planning of validation activities. References [1] ISO 9000:2015 & ISO 9001:2015, Quality Management System [2] NAFEMS, ESQMS:01 Engineering Simulation Quality Management Standard, Jonathan M. Smith NAFEMS, 2020 [3] ASME, Verification, Validation and Uncertainty Quantification Terminology in Computational Modeling and Simulation, ASME VVUQ 1-2022, New York, NY, 2022 [4] ASME, Standard for Verification and Validation in Computational Solid Mechanics, 'œAmerican Society of Mechanical Engineers, ASME V&V 10, New York, NY, 2019