Affiliations: Visualization Research Center, Niigata University,
8050 Ikarashi-2, Niigata, 950-2181, Japan. E-mail: [email protected]
Abstract: Temperature and velocity fields in unsteady non-penetrative
turbulent thermal convection of a horizontal fluid layer are measured in
horizontal and vertical planes simultaneously using the combined liquid-crystal
thermometry and stereo particle image velocimetry (PIV) with high spatial and
temporal resolution. The result shows the formation of convection pattern
across the fluid layer, which originates from the spoke structure over the
heated surface. The upward fluid motion is generated from the intersection of
the bursting lines of the spoke structure, while the downward motion is induced
by the low temperature fluid directing toward the center of the spoke
structure. Thus, the large-scale convective motion is produced in the fluid
layer through the motion of spoke structure. The POD analysis of the
temperature and velocity eigenfunctions shows the existence of large-scale
motion in the fluid layer, which supports the observed convection pattern near
the heated boundary and in the middle of the fluid layer.