A numerical and experimental study of the effects of humidity in the turbulent boundary layer

The turbulent boundary layer is a flow that has received widespread attention from the turbulence community over the last decades, mainly due to its fundamental role in aeronautics, drag reduction and environmental applications. It is a canonical flow that combines both deep physics and geophysical and industrial applications. Its simple geometry makes it particularly suitable for its study via experiments in wind tunnels and computational fluid dynamics.

Despite this intense activity, there remain many open questions, as evidenced by the recently discovered outer peak in the mean square fluctuating streamwise velocity and the new theoretical models developed since.

A paradigmatic application of turbulent boudary layer is the low earth’s atmosphere, as the atmospheric turbulent boundary layer is created due to the interaction of the air flow and earth’s surface. It is an extremely complex flow, where many parameters must be considered in order to obtain an appropriate modelling:

• humidity,
• heat transfer,
• Coriolis force,
• freestream turbulence, among many others.

As even the relatively simpler turbulent boundary layer is far from being understood, the study of the atmospheric turbulent boundary layer is a formidable challenge that requires a description and understanding of every parameter involved in it.

In this project, we propose a study of the role of humidity (water vapour) in the structure of the turbulent boundary layer. Isolating this effect would be of great help for the understanding of both turbulent boundary layer and atmospheric turbulent boundary layer. For this purpose, we will combine wind tunnel experiments and numerical simulations to have access to the velocity and humidity local fluctuating fields.