2015/08/09 by Florent Michel, Michel, Florent, Renaud Parentani +1 · 1 citation
Earth and Planetary Sciences · Engineering · #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Turbulent Flows #General Relativity and Quantum Cosmology (gr-qc) #Meteorological Phenomena and Simulations #Particle Dynamics in Fluid Flows
paper · pdf · doi:10.48550/arxiv.1508.02044
openalex publication_date 2015/08/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We reexamine the scattering coefficients of shallow water waves blocked by a\nstationary counter current over an obstacle. By considering series of\nbackground flows, we show that the most relevant parameter is F rm max,\nthe maximal value of the ratio of the flow velocity over the speed of low\nfrequency waves. For subcritical flows, i.e., F rm max < 1, there is no\nanalogue Killing horizon and the mode amplification is strongly suppressed.\nInstead, when F rm max gtrsim 1.1, the amplification is enhanced at low\nfrequency and the spectrum closely follows Hawking's prediction. We further\nstudy subcritical flows close to that used in the Vancouver experiment. Our\nnumerical analysis suggests that their observation of the "thermal nature of\nthe mode conversion" is due to the relatively steep slope on the upstream side\nand the narrowness of the obstacle.\n