Uncertainty in Computational Fluid Dynamics

Abstract

The Annual EPSRC/IMechE Expert Meeting brought together some 44 experts to consider sources of uncertainty in computational fluid dynamics (CFD). Presentations and discussions covered modelling, numerical solution techniques, boundary conditions, evaluation protocols and QA (quality assurance) procedures. The principal conclusions to emerge were: (a) the need for additional collaborative validation studies; (b) the desirability of introducing appropriate QA procedures, possibly based on the CFD Community Club initiative; (c) the need for additional postgraduate training, possibly based on the IGDS principle; (d) the value of continuing work in modelling and error estimation techniques for numerical schemes.

Probing biological redox chemistry with large amplitude Fourier transformed ac voltammetry

“…In the simplest direct current cyclic voltammetry (dcV) experiment, the potential is either increased or decreased from a starting potential to a turning potential at a linear scan rate, before the direction of change is reversed, and the same rate of potential change is applied, but in the opposite direction. 23 , 25 For example, Fig. 4 illustrates an experiment where the voltage applied to the working electrode at time zero (the starting potential) is –0.8 V versus the reference.…”

“…4A can be derived by introducing potential pre-poises and using different start and end potentials. 23 , 25 …”

“…Non-Faradaic current arises due to the electrocapacitive charging and discharging of the double layer which forms at the electrode-solution interface in response to voltage changes. 23 , 25 Such current is therefore an ever-present background contribution which is measured in all voltammetric experiments. Fig.…”

“…Faradaic current arises from redox reactions at the electrode surface; with net reduction or oxidation giving rise to negative or positive currents, respectively. 23 , 25 In protein or enzyme film dcV (PF-dcV), non-catalytic electron transfer reactions are conceptually the simplest redox reactions to study. However, in practical terms the measurement of Faradaic current arising from catalytic redox reactions is far simpler, and a large amount of the recent PF-dcV literature describes the analysis of such signals.…”

A Benchmark Test Set for Alchemical Free Energy Transformations and Its Use to Quantify Error in Common Free Energy Methods

“…The field of computational fluid dynamics has also grappled with issues of reliability and standardization. During the late 90s, substantial research efforts in the field of computational fluid dynamics (CFD) were focused on establishing validation benchmarks to improve the reliability of CFD simulations in various design applications. − This research helped to bring down costs, increase data fidelity, and reduce design cycle time in the early development phases of new airplanes, Formula 1 cars, treatment and diagnosis of cardiovascular diseases, , and off-shore oil rigs . Similar validation benchmarks were developed for simulations in the nuclear industry, improving the reliability in nuclear reactor safety, underground nuclear waste storage, and nuclear weapon safety .…”