There is a mathematical analogy between the propagation of fields in a general relativistic spacetime and long (shallow water) surface waves on moving water. Hawking argued that black holes emit thermal radiation via a quantum spontaneous emission. Similar arguments predict the same effect near wave horizons in fluid flow. By placing a streamlined obstacle into an open channel flow we create a region of high velocity over the obstacle that can include wave horizons. Long waves propagating upstream towards this region are blocked and converted into short (deep water) waves. This is the analogue of the stimulated emission by a white hole (the time inverse of a black hole), and our measurements of the amplitudes of the converted waves demonstrate the thermal nature of the conversion process for this system. Given the close relationship between stimulated and spontaneous emission, our findings attest to the generality of the Hawking process.
The project is a jointcollaboration between the School of Mathematics at the University of Nottingham (Nottingham, UK) and the University of British Columbia (Vancouver, Canada):
Silke Weinfurtner (School of Mathematics, University of Nottingham)
Matt Penrice (ICTP, Trieste, Italy)
External collaborators:
Bill Unruh (Department of Physics & Astronomy, UBC, Vancouver, Canada)
Greg Lawrence (Department of Civil Engineering, UBC, Vancouver, Canada)
Ted Tedford (Department of Civil Engineerin, UBC, Vancouver, Canada & ICTP/SISSA, Trieste, Italy)
The results of our experiments, that attest for the first detection of Hawking radiation in a tabletop experiment, are published in:

Measurement of stimulated Hawking emission in an analogue system
by Silke Weinfurtner, Edmund W.Tedford, Matthew C.J.Penrice, William G.Unruh and Gregory A.Lawrence

Classical aspects of Hawking radiation verified in analogue gravity experimentby
by Silke Weinfurtner, Edmund W.Tedford, Matthew C.J.Penrice, William G.Unruh and Gregory A.Lawrence
Popular science articles about our experiments:

Tabletop measurements of Hawking radiation (Physics today)
by Richard J. Fitzgerald

Black Holes in the Bathtub (Science news)
by Marissa Cevallos

Making waves (APS Synopsis)
by Jessica Thomas
Below you will find a brief description of the effective spacetime, and a summary of our key results obtained so far.
Experiments at Civil and Mechanical Engineering Laboratories Building (Rusty Hut),
The University of British Columbia (UBC),
Vancouver,
(Canada).
Classical aspects of Hawking radiation verified in analogue gravity experiment
Hydrodynamic simulation of black hole evaporation process
Effective horizons. (above) The propagation of for example sound waves in a convergent fluid flow exhibiting sub and supersonic flow regions are depicted. The dashed (red) black / white lines, separating the sub and supersonic regions, indicate the location of the acoustic black/white horizon. From the left to the right the flow velocity is speeding up and slowing down again. (left) The blocking of surface waves on the effective white hole horizon can be seen in our video taken from our experimental setup.
Effective horizons
Positive & negative norm modes
Paircreation process. (left) Hawking predicted the paircreation of positive and negative 'energy' (more accurately 'norm') particles at the black hole horizon. (right) In our experiment we observed this process at the effective (white hole) horizon. To demonstrate this further, we filtered for the positive (below left) and negative (below right) energy/norm modes.
positive energy
negative energy
positive energy
negative energy
horizon
effective horizon
Boltzmann spectrum
Thermal hypothesis. Hawking also predicted at the ratio between negative to positive norm modes follows a Boltzmann distribution determined by the surface gravity at the horizon. We plotted on the left the logarithm of the this ratio, and as predicted it is following a Boltzmann distribution. In an independent mesurement we were able to directly measure the effective surface gravity, and it is in agreement with the value of the Boltzmann spectrum (i.e. the slope of the curve presented in the image to the left).