## On the transition between regular and irregular shock patterns of shock-wave/boundary-layer interactions

J. Matheis, S. Hickel (2015)*Journal of Fluid Mechanics* 776: 200-234. doi: 10.1017/jfm.2015.319

The reflection of strong oblique shock waves at turbulent boundary layers is studied numerically and analytically. A particular emphasis is put on the transition between regular shock-wave/boundary-layer interaction (SWBLI) and Mach reflection (irregular SWBLI). The classical two- and three-shock theory and a generalised form of the free interaction theory are used for the analysis of well-resolved large-eddy simulations (LES) and for the derivation of stability criteria.

## Benchmarking in a rotating annulus: A comparative experimental and numerical study of baroclinic wave dynamics

M. Vincze, S. Borchert, U. Achatz, T. von Larcher, M. Baumann, C. Liersch, S. Remmler, T. Beck, K.D. Alexandrov, C. Egbers, J. Fröhlich, V. Heuveline, S. Hickel, U. Harlander (2015) *Meteorologische Zeitschrift* 23: 611-635. doi: 10.1127/metz/2014/0600

The differentially heated rotating annulus is a widely studied tabletop-size laboratory model of the general mid-latitude atmospheric circulation. The two most relevant factors of cyclogenesis, namely rotation and meridional temperature gradient are quite well captured in this simple arrangement. The radial temperature difference in the cylindrical tank and its rotation rate can be set so that the isothermal surfaces in the bulk tilt, leading to the formation of baroclinic waves.

## On the construction of a direct numerical simulation of a breaking inertia-gravity wave in the upper-mesosphere

M.D. Fruman, S. Remmler, U. Achatz, S. Hickel (2014) *Journal of Geophysical Research *119: 11613-11640. doi: 10.1002/2014JD022046

A systematic approach to the direct numerical simulation (DNS) of breaking upper mesospheric inertia-gravity waves of amplitude close to or above the threshold for static instability is presented. Normal mode or singular vector analysis applied in a frame of reference moving with the phase velocity of the wave (in which the wave is a steady solution) is used to determine the most likely scale and structure of the primary instability

## Large-eddy simulation of passive shock-wave/boundary-layer interaction control

V. Pasquariello, M. Grilli, S. Hickel, N.A. Adams (2014) *International Journal of Heat and Fluid Flow *49: 116-127. doi: 10.1016/j.ijheatfluidflow.2014.04.005

We investigate a passive flow-control technique for the interaction of an oblique shock generated by an 8.8° wedge with a turbulent boundary-layer at a free-stream Mach number of Ma_{∞ }= 2.3 and a Reynolds number based on the incoming boundary-layer thickness of Re_{δ} = 60 500 by means of large-eddy simulation (LES).

## On the application of WKB theory for the simulation of the weakly nonlinear dynamics of gravity waves

J. Muraschko, M.D. Fruman, U. Achatz, S. Hickel, Y. Toledo (2015) *Quarterly Journal of the Royal Meteorological Society* 141: 676-697. doi: 10.1002/qj.2381

The dynamics of internal gravity waves is modelled using Wentzel–Kramer–Brillouin (WKB) theory in position–wave number phase space. A transport equation for the phase-space wave-action density is derived for describing one-dimensional wave fields in a background with height-dependent stratification and height- and time-dependent horizontal-mean horizontal wind, where the mean wind is coupled to the waves through the divergence of the mean vertical flux of horizontal momentum associated with the waves.

## Direct numerical simulation of a breaking inertia-gravity wave

S. Remmler, M.D. Fruman, S. Hickel (2013) *Journal of Fluid Mechanics *722: 424-436. doi: 10.1017/jfm.2013.108

We have performed fully resolved three-dimensional numerical simulations of a statically unstable monochromatic inertia–gravity wave using the Boussinesq equations on an* f *- plane with constant stratification. The chosen parameters represent a gravity wave with almost vertical direction of propagation and a wavelength of 3 km breaking in the middle atmosphere.