About my postdoc project at Stockholm University

eTurb: Efficient simulations of turbulence in atmospheric boundary layers

Since October 1, 2019 I have been working as a postdoc at MISU, Stockholm University. There has been a couple of meetings with the group involved, and now the who and the what are more concrete. I wrote a short abstract for the annual FLOW catalogue, which I share below.

eTurb: Efficient simulations of turbulence in atmospheric boundary layers

A. V. Mohanan, G. Brethouwer, M. Kupiainen, J. Nordström, D. S. Henningson, P. Schlatter & G. Svensson

Funding: Swedish e-Science Research Centre (SeRC)

The atmospheric boundary layer (ABL) is the region which interacts with the Earth’s surface and exchanges energy between larger geophysical scales and land. The ABL goes through different regimes of stratification during the day-night transition, referred to as the diurnal cycle. Daytime convection results in a mixed layer when the boundary layer depth increases, and during night as the land cools, a shallower stably stratified boundary layer is observed. Accurate representation of turbulence in the ABL is crucial e.g. to improve weather predictions and for wind-energy applications. A suitable tool for studying the turbulence and complex transient phenomena in the ABL during a typical diurnal cycle is large-eddy simulation (LES).

This project aims to tackle different modelling challenges along the road to an efficient LES of the ABL. From the physics perspective, the wall boundary condition and the LES subgrid-scale model need to be improved to allow for high resolution simulations. Existing models should also be verified with regards to numerical stability and consistency. A desired outcome of this project is an efficient and accurate code for an LES of diurnal cycle of the ABL. To coordinate this inter-disciplinary project a collaboration between KTH, SU, LiU and SMHI is set afoot. For the LES we will use the Nek5000 (KTH and SU) and ESSENSE (LiU and SMHI) codes.

Atmospheric boundary layer

Ashwin Vishnu Mohanan

About the author

Ashwin Vishnu Mohanan, Ph.D. in Fluid mechanics