流体中两个尺度下的热对流的相互作用检测方案(粒子图像测速)

Dripping convective instabilities develop under a cold thermal boundary layer when the local Rayleigh number exceeds a critical value Rac (Howard, 1966). Their 86 Interaction of two scales of thermal convection in viscous fluids interaction with a shear flow is studied experimentally in a cavity heated from one vertical wall and cooled from above. Rayleigh numbers range between 104 and 108, and Prandtl numbers are greater than 1000. Within this parameter range, a hot horizontal jet develops under the cold boundary. The instabilities dripping from the latter are therefore sheared by the flow and remain trapped in the jet, following a helicoidal path with axis parallel to the jet flow. For high jet velocities compared to the dripping velocity, 2D steady rolls prevail, while for low jet velocities, a 3D structure is observed. A phase diagram and scaling laws for the flow characteristics are determined.