Abstract
Buoyant plume above heated horizontal cylinders observed by thymol blue technique and thermal structure have been measured by thermocouples in a shallow water layer with a free air interface. Hydrodynamic conditions are characterized by the swaying motion of laminar plume above cylinders. Recirculation is induced when the plume interacts with the air-water interface or with the adjoining plumes. Temperature measurements and flow visualization reveal the existance of unstable temperature gradients below the interface and nearly isothermal region extends from the mixing layer to approximately the level of the cylinder and stable temperature gradient below the cylinders.
