2014 Volume 9 Issue 3 Pages JFST0030
In this study, the Schmidt number dependence of the scalar statistics and velocity-scalar joint statistics is investigated experimentally in a liquid axisymmetric jet. In the experiments, the axial velocity, radial velocity, concentration of the diffusing dyes, and temperature are measured by an X-type hot-film, optical fiber probes, and an I-type cold-film, respectively. In addition simultaneous measurements of velocities and concentration, and velocities and temperature are also conducted. As diffusing dyes, C.I.Direct Blue 86 and Rhodamine 6G are chosen whose Schmidt numbers are 3,800 and 1,000, respectively. The Prandtl number of temperature is about 7. Experimental results show that the Schmidt number dependence of the spatial derivative statistics is observed. The skewness of concentration spatial derivative is smaller than that of temperature spatial derivative. Further, the radial velocity-concentration cospectrum and radial velocity-temperature cospectrum show differences each other. The slope of radial velocity-temperature cospectrum is -7/3, while that of radial velocity-concentration cospectrum is about-2.
