This presentation was made at CAASE18, The Conference on Advancing Analysis & Simulation in Engineering. CAASE18 brought together the leading visionaries, developers, and practitioners of CAE-related technologies in an open forum, to share experiences, discuss relevant trends, discover common themes, and explore future issues.

Resource Abstract

The growing trend of simulation democratization and utilization of Computational Fluid Dynamics (CFD) by non-expert analysts has come with the promise of enabling reduced product development time and cost by providing insights key to making design choices earlier in the development process. While this is an understandably attractive proposition, this trend also elevates the level of concerns and risks associated with the potentially negative impacts from the generation, interpretation, and application of CFD simulations by non-experts, especially using non-validate methodologies. The proliferation of results generated using non-validated CFD methodologies may have serious consequences on design decisions, which may more than offset the initial benefit in project schedule and cost when test results or more detailed and validation simulations are performed with unexpected results. For some control valve designs, it has been observed that seemingly trivial changes to meshing inputs can result in unexpectedly large effects on valve capacity predictions. This sensitivity to small input changes is further magnified by the selection of and coupling with an appropriate turbulence model for massively separated and complex recirculating flows. In light of these observations, the importance of validating CFD simulation methodology against test results and the involvement of analysts with suitable competency in the simulation workflow to assist in assuring the quality of results is highlighted. Real-world examples of these unexpected sensitivities are explored, along with a discussion of their potential impacts if validation efforts had not been pursued. If non-validated CFD methodologies are employed early in the design cycle, the expected benefits may not be realized due to unquantified or uncharacterized deficiencies in the method. In contrast to CFD analysis tools where these modeling and meshing choices are typically made behind the scenes without any user involvement or awareness, the presented approach uncovers unexpected modeling sensitivities and poor assumptions before these issues can drive a design process down a path of unnecessary costs and schedule delays.