Effect of bottom-wall superheat on flow structure and heat transfer enhancement in bubbly natural convection
(2026) APS Division of Fluid Dynamics Annual Meeting 2026 — Location: Orlando, Florida, USA (22.November.2026)
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- Abstract
- (en) We present direct numerical simulations of bubble-enhanced natural convection in a water-filled cavity with a superheated bottom wall and a subcooled free surface. The liquid phase is solved in an Eulerian framework, while the bubbles are tracked using a Lagrangian approach with two-way coupling between the phases. We employ a bubble-nucleation model that allows bubbles to be generated in response to the local thermal conditions. Further, the effect of evaporation across the free surface is taken into account via a model based on film theory. Our study investigates the influence of bottom-wall superheat on flow structure and convective heat transfer. At low superheat, bubbles condense rapidly and have little influence on the flow. As the superheat increases, bubbles grow larger and rise higher into the cavity, restructuring and strengthening the large-scale circulation, as evidenced by increased liquid vertical velocities. In addition, bubbles enhance thermal mixing, resulting in a more uniform temperature distribution throughout the bulk and a substantial increase in convective heat transfer. In this talk, we first discuss the emergence of the different flow structures. We then present flow statistics, including temperature and velocity fields, bubble size and vertical concentration profiles, to further elucidate the role of bubble–liquid interactions in the flow structure and heat convection.
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Li, H., & Papalexandris, M. (2026, November 23). Effect of bottom-wall superheat on flow structure and heat transfer enhancement in bubbly natural convection. APS Division of Fluid Dynamics Annual Meeting 2026, Orlando, Florida, USA. https://hdl.handle.net/2078.5/281612