Atmospheric gravity waves in a gas centrifuge

Field observations of nonlinear atmospheric gravity waves are sparse and involved due to many challenges for the instrumentation. Due to these complications of field measurements, laboratory experiments are an indispensable tool.

As of today, all laboratory experiments on gravity waves have in common that they were performed with water as the working fluid. Due to flow similarities, most of the features observed in the water tanks are equally valid for the atmosphere. However, one particular property of air cannot be emulated by water: compressibility. Especially for the dynamics of nonlinear waves, compressibility plays a significant role.

We propose a laboratory experiment by means of a rapidly rotating gas centrifuge. The centrifugal forces act on the gas like the gravitational pull causing a stratified compressible working fluid. In this device, atmosphere-like gravity waves would be observable under controlled and replicable conditions for the first time.

We show that the waves in a centrifuge would theoretically behave like their atmospheric counterparts; they exhibit the same dispersion and polarization relations. Futhermore, spinning the centrifuge with the right frequency, there is a clear scale separation between acoustic and gravity waves. In addition to the centrifugal force, the Coriolis force acts in the same plane potentially spoiling the similarities. However, the influence of the Coriolis force on the wave is negligibly small.