Highly-resolved three-dimensional velocity measurements via dual-plane stereo particle image velocimetry (DSPIV) in turbulent flows

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76106/1/AIAA-2002-290-824.pd

Dual-plane stereo particle image velocimetry measurements of velocity gradient tensor fields in turbulent shear flow. II. Experimental results

Results are presented from highly resolved dual-plane stereo particle image velocimetry (DSPIV) measurements for the structure, statistics, similarity, and scaling of all nine simultaneous components of the velocity gradient tensor fields ∂ui/∂xj∂ui∕∂xj on the quasi-universal intermediate and small scales of turbulent shear flows. Measurements were obtained at three combinations of the outer-scale Reynolds number ReδReδ and the local mean shear rate SS in the fully developed self-similar far field of a turbulent jet, and thus reflect the combined effects of the large-scale structure, spatial inhomogeneities, and anisotropies inherent in such a flow. Conditions addressed in this study correspond to local outer-scale Reynolds numbers Reδ = 6,000Reδ=6,000 and 30,000 and local mean shear values Sδ/uc = 0Sδ∕uc=0 and 1.7, corresponding to Taylor-scale Reynolds numbers Reλ ≈ 44Reλ≈44 and 113 and shear rates Sk/ε = 0Sk∕ε=0 and 2.1. Gradient fields investigated here include the individual velocity gradient component fields, the strain rate component fields and the associated principal strain rates, the vorticity component fields and their orientations with respect to the principal strain axes, the enstrophy and enstrophy production rate fields, and the true kinetic energy dissipation rate field. Results normalized on both inner- and outer-scale variables are presented to allow interpretation relative to the similarity and scaling implied by classical turbulence theory. For both ReδReδ values at S = 0S=0, results show that most aspects of these gradient fields are essentially in agreement with the predictions from homogeneous isotropic turbulence, while for S ≠ 0S≠0 there are significant and consistent departures from isotropy. Results also provide direct measurements of the exponential scaling factors in the left and right tails of the velocity gradient distributions, as well as quantification of the inner (viscous) length scales in the enstrophy and dissipation rate fields. In addition, strong evidence for multifractal scale similarity at length scales greater than about twice the viscous length λνλν is found in both the enstrophy and dissipation rate fields.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87499/2/035102_1.pd

Dual-plane stereo particle image velocimetry measurements of velocity gradient tensor fields in turbulent shear flow. I. Accuracy assessments

Results are presented from quantitative assessments of the accuracy of velocity gradients measured by a dual-plane stereo particle image velocimetry (DSPIV) technique that allows direct, highly resolved, nonintrusive measurements of all nine simultaneous components of the velocity gradient tensor fields ∂ui/∂xj∂ui∕∂xj at the quasi-universal intermediate and small scales of turbulent shear flows. The present results systematically determine the sources of errors in DSPIV measurements and the resulting accuracy of velocity gradients obtained from such measurements. Intrinsic errors resulting from asymmetric stereo imaging are found by synthetic particle imaging to be no larger than 0.8%. True particle imaging in finite-thickness light sheets is found from single-plane imaging tests to produce net errors in measured velocity differences of 6% for in-plane components and 10% for out-of-plane components. Further errors from limits on the accuracy of independent dual light sheet generation and positioning are found from coincident-plane imaging tests to produce overall errors of 9% and 16% in the in-plane and out-of-plane velocity differences. Practical DSPIV velocity gradient component measurements are found from separated-plane imaging tests in a turbulent shear flow to show excellent similarity in on-diagonal (i = j)(i=j) and off-diagonal (i ≠ j)(i≠j) components of ∂ui/∂xj∂ui∕∂xj, as well as mean-square gradient values showing agreement within 1%–4% of ideal isotropic limit values. The resulting measured divergence values are consistent with overall rms errors obtained from the coincident-plane imaging tests. Collectively, these results establish the accuracy with which all nine simultaneous components of the velocity gradient tensor fields ∂ui/∂xj∂ui∕∂xj can be obtained from DSPIV measurements at the quasi-universal intermediate and small scales of turbulent shear flows.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87388/2/035101_1.pd

Quantifying injury to common bottlenose dolphins from the Deepwater Horizon oil spill using an age-, sex- and class-structured population model

Field studies documented increased mortality, adverse health effects, and reproductive failure in common bottlenose dolphins Tursiops truncatus following the Deepwater Horizon (DWH) oil spill. In order to determine the appropriate type and amount of restoration needed to compensate for losses, the overall extent of injuries to dolphins had to be quantified. Simply counting dead individuals does not consider long-term impacts to populations, such as the loss of future reproductive potential from mortality of females, or the chronic health effects that continue to compromise survival long after acute effects subside. Therefore, we constructed a sex- and agestructured model of population growth and included additional class structure to represent dolphins exposed and unexposed to DWH oil. The model was applied for multiple stocks to predict injured population trajectories using estimates of post-spill survival and reproductive rates. Injured trajectories were compared to baseline trajectories that were expected had the DWH incident not occurred. Two principal measures of injury were computed: (1) lost cetacean years (LCY); the difference between baseline and injured population size, summed over the modeled time period, and (2) time to recovery; the number of years for the stock to recover to within 95% of baseline. For the dolphin stock in Barataria Bay, Louisiana, the estimated LCY was substantial: 30 347 LCY (95% CI: 11 511 to 89 746). Estimated time to recovery was 39 yr (95% CI: 24 to 80). Similar recovery timelines were predicted for stocks in the Mississippi River Delta, Mississippi Sound, Mobile Bay and the Northern Coastal Stock.Publisher PDFPeer reviewe

Novel patient-derived xenograft mouse model for pancreatic acinar cell carcinoma demonstrates single agent activity of oxaliplatin

Additional file 4: Figure S3. Integrated genomic viewer (IGV) of BRCA2 gene. IGV displays genomic data of the PA-018 PAAC PDTX model. Chromosome 13 (Chr 13) is shown and 5bp deletions are found after position 32907365 (c.1755_1759del5), this region resides on exon 10 of BRCA2. The bottom of the image shows the nucleotides and amino acids that correspond to the reference sequence of the BRCA2 gene and protein

Dual-plane stereo particle image velocimetry (DSPIV) for measuring velocity gradient fields at intermediate and small scales of turbulent flows

A two-frequency dual-plane stereo particle image velocimetry (DSPIV) technique is described for highly resolved measurements of the complete nine-component velocity gradient tensor field ∂ u i /∂ x j on the quasi-universal intermediate and small scales of turbulent flows. The method is based on two simultaneous, independent stereo particle image velocimetry (PIV) measurements in two differentially spaced light sheet planes, with light sheet characterization measurements demonstrating the required sheet thicknesses, separation, and two-axis parallelism that determine the measurement resolution and accuracy. The present approach uses an asymmetric forward–forward scatter configuration with two different laser frequencies in conjunction with filters to separate the scattered light onto the individual stereo camera pairs, allowing solid metal oxide particles to be used as seed particles to permit measurements in nonreacting as well as exothermic reacting turbulent flows.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47075/1/348_2004_Article_898.pd

Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV

Isolated photon production is measured in proton-proton and lead-lead collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80 GeV with the CMS detector at the LHC. The measured ET spectra are found to be in good agreement with next-to-leading-order perturbative QCD predictions. The ratio of PbPb to pp isolated photon ET-differential yields, scaled by the number of incoherent nucleon-nucleon collisions, is consistent with unity for all PbPb reaction centralities.Comment: Submitted to Physics Letters