This paper presents an experimental study on wave interactions with arectangular barge in a beam sea condition. Regular waves with a waveperiod the same as the natural frequency of the barge were used in the experiments due to the fact that the barge is prone to capsizing under such waves. The barge was fixed on the free surface and no waveovertopping was assumed. Particle Image Velocimetry (PIV) wasemployed to measure the full-field two-dimensional velocity. Since the flow is highly turbulent, the phase-averaging technique was used to the extract the mean flow and turbulence properties. The mean flowpattern, including velocity, vorticity, and streamline, was analyzed to quantify the mechanism of the interactions. The generation andevolution of vorticity and turbulence kinetic energy were demonstrated.The turbulent kinetic energy is found to highly correlate with the vorticity field
Auto-Compensating LII (AC-LII) two-color pyrometry to determine theparticle temperature— permits use of low-fluence— particles are kept below the sublimationtemperature this new technique automaticallycompensates for any changes in theexperimental conditions— fluctuations in local ambient temperature— variation in laser fluence— laser beam attenuation by the particulatematter— desorption of condensed volatile materialAC-LII Features in situ and nonintrusive signal is proportional to soot volumefraction spatially resolved time resolved large measurement range— not limited by aggregate size high precision and repeatability high speed data acquisition and analysisAC-LII Benefits dilution of sample not required stable measurement of elemental carbon insensitive to presence of other species can operate at very low concentrations real-time results cycle-resolved measurements possible can provide particulate morphology (size,size distribution, number density) whencombined with scattering
Microscopic particle image velocimetry (microPIV) experiments were performed on a polydimethylsiloxane (PDMS) microchannelwith a cross-section measuring 320 lm 330 lm for Reynolds numbers between 272 and 2853. Care was taken to ensure that theseed particle density was great enough that accurate instantaneous velocity vector fields could be obtained for all the Reynolds numbersinvestigated. Velocity fluctuations were calculated from ensembles of microPIV velocity fields. The hu0i/umax fluctuation showedan increase at Re = 1535 and a further increase as Reynolds numbers were increased, suggesting that transition to turbulence begannear Re = 1535, a Reynolds number lower than predicted by classical theory. The hu0i/umax data also suggest the flow was fullydevelopedat a Reynolds number between 2630 and 2853, also lower than classical results. This finding was confirmed in plots ofthe mean velocity profile. For the fully developed flow, the measured hu0 i/umax fluctuation agreed well with classical results for turbulentduct flow, but the hv0 i/umax fluctuation was 25–40% lower than turbulent duct flow results. Finally, spatial correlations ofvelocity fluctuations were calculated to lend some insights into the characteristics of the large-scale turbulent structures observedin the turbulent microchannel flow.