Modification of turbulence in Rayleigh-B ?enard convection by phase change


Heavy or light particles introduced into a liquid trigger motion due to their buoyancy, with the potential to drive flow to a turbulent state. In the case of vapor bubbles present in a liquid near its boiling point, thermal coupling between the liquid and vapor can moderate this additional motion by reducing temperature gradients in the liquid. Whether the destabilizing mechanical feedback or stabilizing thermal feedback will dominate the system response depends on the number of bubbles present and the properties of the phase change. Here we study thermal convection with phase change in a cylindrical Rayleigh–Bénard cell to examine this competition. Using the Reynolds number of the flow as a signature of turbulence and the intensity of the flow, we show that in general the rising vapor bubbles destabilize the system and lead to higher velocities. The exception is a limited regime corresponding to phase change with a high latent heat of vaporization (corresponding to low Jakob number), where the vapor bubbles can eliminate the convective flow by smoothing temperature differences of the fluid.





Copyright 2011 New Journal of Physics. Recommended citation: Schmidt, Laura E., Paolo Oresta, Federico Toschi, Roberto Verzicco, Detlef Lohse, and Andrea Prosperetti. "Modification of turbulence in Rayleigh–Bénard convection by phase change." New journal of physics 13, no. 2 (2011): 025002. DOI: 10.1088/1367-2630/13/2/025002 URL: Reproduced in accordance with the original publisher’s licensing terms and with permission from the author(s).