Modeling of high-Re, incompressible, non-equilibrium, rough-wall boundary layers for naval applications under NATO-AVT349

Kurzfassung

This paper will discuss the modeling activity of NATO-STO Research Task Group AVT-349. The aim of this group is to improve the understanding and modeling of boundary layers in the complex flow around water vehicles. As such, the focus is on incompressible, high-Reynolds-number flows that can be subject to non-equilibrium conditions such as strong pressure gradients, three-dimensionality, and surface roughness and heterogeneity. The Task Group has identified a reduced number of simpler problems in which the above conditions can be studied separately and in controlled environments. These include two-dimensional rough-wall boundary layers under both zero and non-zero pressure gradients, two-dimensional smooth-wall boundary layers subject to pressure gradients, and boundary layers around smooth bodies of revolution and three-dimensional obstacles. An experimental and computational data set is being assembled for further analysis and insight into the flow mechanisms involved, as well as the shortcomings of state-of-the-art models. This talk will present the outlook for the modeling effort within the Task Group, as well its different objectives. These include predicting the effect of roughness in equilibrium conditions, assessing the applicability and/or extension of equilibrium predictions to non- equilibrium conditions, in particular when outerlayer similarity is lost; the development of near-wall models based on a reduced-order resolvent framework; and the use of machine-aided methods in closure models.