## Generic side mirror

The flow around the generic side mirror of a car or a train is a typical benchmark simulation for turbulent flows. The side mirror is modelled by a half cylinder and a quarter of a sphere, and it is attached to a flat plate representing the side of the vehicle.

## Volcanic eruption (turbulent jet)

A volcano propels gases into the athmosphere. In this 3D case study, the problem is represented by means of a turbulent jet with lateral side wind. Many interesting physical ingredients of a turbulent flow are reproduced in this application. While a simple turbulent shear layer is formed on the side opposed to the wind, the region protected from the wind is characterised by a complex interaction of turbulent structures detaching from the plume and from boundary layers on the ground and on the cone of the volcano.

## Kelvin Helmholtz instability (3D)

A 3D Kelvin-Helmholtz instability, describing the blending of two immiscible fluids with a shearing motion, is simulated at high resolution. The aim is to compute the pattern of the interface between the fluids. This is done first through a continuum advection equation, and then by injecting discrete particles. Due to the numerical diffusion in the continuum equation, much sharper figures are obtained with the particles.

## Cylindrical T-junction

Two same-diameter cylinders are connected at a 90% angle, forming a t-shape. A constant flow pours in through the left branch of the horizontal cylinder and splits into the two connecting branches. Numerically challenging due to the sharp edges and the long-tailed vortex in the vertical branch, this model is of interest for the study of artery grafts in medical physics.

## Grabowski-Berger rotational flow

The geometry and boundary condition of this 3D flow have cylindrical symmetry. This symmetry breaks at a critical Reynolds number, with a production of helix branches. A regime with a double-helix is shown in this demo. The flow is visualized through injected passive tracer particles.

## Rayleigh-Taylor Instability (2D)

A heavy fluid sits initially on top of a light fluid. When the symmetry is broken, an instability occurs and the heavy fluids penetrates into the light one.

## Dipole-Wall collision

This two-dimensional turbulent flow illustrates the interaction between a vortex and a no-slip wall. From the initial condition, a pair of counter-rotating vortices is self-propelled to the right. The system is confined in a square box with no-slip wall. At the contact with the right wall, additional vortices detach from the boundary layer, break apart the original vortex pair to form two secondary pairs. These describe a circular path to bounce against the wall a few more times.