NODESIM-CFD - Non-deterministic simulation for CFD-Based Design methodologies
Overview
Background & policy context:
Analysis and design methods in aeronautical industry, particularly the aerodynamic simulation tools based on Computational Fluid Dynamics (CFD) and their multidisciplinary extensions (such as fluid-structure; fluid-thermal; aero-acoustics applications), are based on simulations with a unique set of input data and model variables. However, realistic operating conditions are a superposition of numerous uncertainties under which the industrial products operate (uncertainties on boundary and initial conditions, on geometries resulting from manufacturing tolerances, numerical error sources and uncertain physical model parameters. The presence of these uncertainties is the major source of risk in the design decision process and increases therefore the level of risks of failure of a given component.
Objectives:
The NODESIM-CFD project addressed the EU objectives of reduction of aircraft development costs and increase of safety, through the introduction of a new paradigm for computational fluid dynamics (CFD)-based virtual prototyping, aimed at the incorporation of operational and other uncertainties in the simulation process. The project pursued the following scientific and technological objectives:
- identification and quantification of the uncertainty parameters associated to a wide variety of aeronautical applications; the domains of application cover: engine aerodynamics, wing aerodynamics, conjugate heat transfer and fluid-structure interactions;
- development of several non-deterministic methodologies focusing on the most promising methods, such as perturbation techniques and adjoint-based methods, efficient Monte Carlo (MC) methods and polynomial chaos methods;
- applications to subsystems and systems: the general methodologies and software tools developed under the previous actions will be applied, tested and validated for the various applications for which the uncertainty variables have been identified and analysed;
- introduction of non-deterministic simulations into the design and decision process, focusing on the development of aerodynamic optimisation algorithms that provide designs, which are robust with respect to uncertainties in geometry, operating conditions, and code simulation uncertainties, and to control and reduce risks by providing designs with aerodynamic performances insensitive to intrinsically uncertain quantities;
- stimulate the scientific cooperation and transfer of knowledge within the NODESIM-CFD consortium, through a specific task of support from the developers to the implementation of the developed new methodologies in the in-house codes of the industrial partners.
Methodology:
The NODESIM-CFD project was composed of the following action lines:
- the identification and probabilistic quantification of the most significant uncertainty sources, related to CFD and multidisciplinary based simulations, of aeronautical components (wings, aircraft and engines);
- the development and incorporation of efficient non-deterministic methodologies into the CFD simulation systems to produce reliability bounds of the predictions in a rational way;
- application and evaluation of the developed methodologies to the non-deterministic analysis of aeronautical components by the industrial manufacturers;
- the development and application of robust CFD-based design methodologies incorporating the non-deterministic based simulations, enabling rational estimates of probabilities of failure.
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