8,122 research outputs found
Static pressure correction in high Reynolds number fully developed turbulent pipe flow
Measurements are reported of the error in wall static pressure reading due to the finite size of the pressure tapping. The experiments were performed in incompressible turbulent pipe flow over a wide range of Reynolds numbers, and the results indicate that the correction term (as a fraction of the wall stress) continues to increase as the hole Reynolds number increases, contrary to previous studies. For small holes relative to the pipe diameter the results follow a single curve, but for larger holes the data diverge from this universal behaviour at a point that depends on the ratio of the hole diameter to the pipe diameter
Turbulence modeling in shock wave/turbulent boundary layer interactions
The research performed was an experimental program to help develop turbulence models for shock wave boundary layer interactions. The measurements were taken in a Mach 3, 16 deg compression corner interaction, at a unit Reynolds number of 63 x 10(exp 6)/m. The data consisted of heat transfer data taken upstream and downstream of the interaction, hot wire measurements of the instantaneous temperature and velocity fluctuations to verify the Strong Reynolds Analogy, and single- and double-pulsed Rayleigh scattering images to study the development of the instantaneous shock/turbulence interaction
Adaptation of WASH Services Delivery to Climate Change and Other Sources of Risk and Uncertainty
This report urges WASH sector practitioners to take more seriously the threat of climate change and the consequences it could have on their work. By considering climate change within a risk and uncertainty framework, the field can use the multitude of approaches laid out here to adequately protect itself against a range of direct and indirect impacts. Eleven methods and tools for this specific type of risk management are described, including practical advice on how to implement them successfully
Non-equilibrium noise in the (non-)Abelian fractional quantum Hall effect
We analyse the noise of the edge current of a generic fractional quantum Hall
state in a tunnelling point contact system. We show that the non-symmetrized
noise in the edge current for the system out-of-equilibrium is completely
determined by the noise in the tunnelling current and the Nyquist-Johnson
(equilibrium) noise of the edge current. Simply put, the noise in the
tunnelling current does not simply add up the equilibrium noise of the edge
current. A correction term arises associated with the correlation between the
tunnelling current and the edge current. We show, using a non-equilibrium Ward
identity, that this correction term is determined by the anti-symmetric part of
the noise in the tunnelling current. This leads to a non-equilibrium
fluctuation-dissipation theorem and related expressions for the excess and shot
noise of the noise in the edge current. Our approach makes use of simple
properties of the edge, such as charge conservation and chirality, and applies
to generic constructions of the edge theory which includes edges of non-Abelian
states and edges with multiple charged channels. Two important tools we make
use of are the non-equilibrium Kubo formula and the non-equilibrium Ward
identity. We discuss these identities in the appendix.Comment: 20 pages, 5 figure
Reynolds number dependence of streamwise velocity spectra in turbulent pipe flow
Spectra of the streamwise velocity component in fully developed turbulent pipe flow are presented for Reynolds numbers up to 5.7×10^6. Even at the highest Reynolds number, streamwise velocity spectra exhibit incomplete similarity only: while spectra collapse with both classical inner and outer scaling for limited ranges of wave number, these ranges do not overlap. Thus similarity may not be described as complete, and a region varying with the inverse of the streamwise wave number, k1, is not expected, and any apparent k1-1 range does not attract any special significance and does not involve a universal constant. Reasons for this are suggested
Study of the structure of turbulent shear flows at supersonic speeds and high Reynolds number
A major effort to improve the accuracies of turbulence measurement techniques is described including the development and testing of constant temperature hot-wire anemometers which automatically compensate for frequency responses. Calibration and data acquisition techniques for normal and inclined wires operated in the constant temperature mode, flow geometries, and physical models to explain the observed behavior of flows are discussed, as well as cooperation with computational groups in the calculation of compression corner flows
Longitudinal spin-relaxation in nitrogen-vacancy centers in electron irradiated diamond
We present systematic measurements of longitudinal relaxation rates ()
of spin polarization in the ground state of the nitrogen-vacancy (NV) color
center in synthetic diamond as a function of NV concentration and magnetic
field . NV centers were created by irradiating a Type 1b single-crystal
diamond along the [100] axis with 200 keV electrons from a transmission
electron microscope with varying doses to achieve spots of different NV
center concentrations. Values of () were measured for each spot as a
function of .Comment: 4 pages, 8 figure
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