Workshop Twente 2020 Online meeting

NDNS+ WORKSHOP June 22-23, 2020      online meeting

22-23 June 2020 

Speaker: Wouter Edeling - CWI

Title:  Model error in turbulent flow simulations

Most numerical simulations of turbulent flow only capture a limited portion of all spatial and temporal scales present in the problem. The effect of the unresolved flow scales enters the resolved-scale equations as an unclosed forcing term, which introduces the need for ad-hoc turbulence closure models. While this procedure results in a computationally tractable problem, the closure models are subject to a various sources of uncertainty, casting doubt on their predictions. The first source of uncertainty are the parameters of the closure models, for which no universal values exist. Secondly, a more challenging form of uncertainty is the so-called model error, which is the error introduced by the assumptions made in the mathematical form of the model. We will give an overview of different (data-driven) techniques to quantify these uncertainties, and discuss remaining challenges. Our overall goal is to put error bars on computational predictions, especially when the closure model is applied outside the set of flow scenarios on which it was originally calibrated.