Fluid mechanics plays a role of great importance in everyday life - in the world around us, and even inside our own body. The variety of fluid-dynamical phenomena is almost endless.

Fluid dynamics works on vastly different length scales
Fluid dynamical phenomena show a rich variety in their appearance, but also in their length and time scales. To mention just two situations:

The vortices produced by the flapping wings of a fruit fly (Drosophila) are smaller than 1 mm in size, while coherent structures formed in accretion disks of neutron stars have a typical size of 100 Astronomical Units. Even bigger: the length scale associated with colliding galaxies is a multitude of light years. The time scale of the eddies produced by the hovering Drosophila is less than one second, while that of galaxy collisions is billions of years. Moreover, gas particles passing a shock wave undergo very drastic changes within a time scale less than 1 µs.

The excitement of fluid mechanics is that flow on these vastly different scales is described by the same basic equations.  Research in our laboratory ranges from flow at the microscale to vortices and turbulence on scales that span the globe.