A5028198279- Fluid Dynamics and Turbulent Flows
- Wind and Air Flow Studies
- Aerodynamics and Acoustics in Jet Flows
- Particle Dynamics in Fluid Flows
- Wind Energy Research and Development
- Meteorological Phenomena and Simulations
- Fluid Dynamics and Vibration Analysis
- Flow Measurement and Analysis
- Aerodynamics and Fluid Dynamics Research
- Heat Transfer Mechanisms
- Plant Water Relations and Carbon Dynamics
- Biomimetic flight and propulsion mechanisms
- Surface Modification and Superhydrophobicity
- Advanced Sensor Technologies Research
- Computational Fluid Dynamics and Aerodynamics
- Turbomachinery Performance and Optimization
- Gas Dynamics and Kinetic Theory
- Heat Transfer and Optimization
- Aerospace and Aviation Technology
- Tribology and Lubrication Engineering
- Fluid Dynamics and Heat Transfer
- Adhesion, Friction, and Surface Interactions
- Rheology and Fluid Dynamics Studies
- Fluid Dynamics and Mixing
- Nuclear Engineering Thermal-Hydraulics
Princeton University
2015-2024
Proteogenomics Research Institute for Systems Medicine
2009-2015
École Polytechnique Fédérale de Lausanne
2012
Chalmers University of Technology
2007
Abstract Considerable discussion over the past few years has been devoted to question of whether logarithmic region in wall turbulence is indeed universal. Here, we analyse recent experimental data Reynolds number range nominally $2\times 1{0}^{4} \lt {\mathit{Re}}_{\tau } 6\times 1{0}^{5} $ for boundary layers, pipe flow and atmospheric surface layer, show that, within uncertainty, support existence a universal region. The results theory Townsend ( Structure Turbulent Shear Flow , Vol. 2,...
Both the inherent intractability and complex beauty of turbulence reside in its large range physical temporal scales. This scales is captured by Reynolds number, which nature many engineering applications can be as 10(5)-10(6). Here, we report measurements over an unprecedented numbers using a unique combination high-pressure air facility new nanoscale anemometry probe. The results reveal previously unknown universal scaling behavior for turbulent velocity fluctuations, remarkably similar to...
A nanoscale thermal anemometry probe (NSTAP) has been developed to measure velocity fluctuations at ultra-small scales. The sensing element is a free-standing platinum wire, 100 nm × 2 μm 60 μm, suspended between two current-carrying contacts and the sensor an order of magnitude smaller than presently available commercial hot wires. constructed using standard semiconductor MEMS manufacturing methods, which enables many probes be manufactured simultaneously. Measurements were performed in...
Abstract Measurements of the streamwise component turbulent fluctuations in fully developed smooth and rough pipe flow are presented over an unprecedented Reynolds number range. For numbers $R{e}_{\tau } \gt 20\hspace{0.167em} 000$ , stress closely follows scaling mean velocity profile, independent roughness, same spatial extent. This observation extends findings a logarithmic law turbulence as reported by Hultmark, Vallikivi & Smits ( Phys. Rev. Lett. vol. 108, 2012) to include flows....
Measurements are presented in zero-pressure-gradient, flat-plate, turbulent boundary layers for Reynolds numbers ranging from $\mathit{Re}_{{\it\tau}}=2600$ to $\mathit{Re}_{{\it\tau}}=72\,500$ ( $\mathit{Re}_{{\it\theta}}=8400{-}235\,000$ ). The wind tunnel facility uses pressurized air as the working fluid, and combination with MEMS-based sensors resolve small scales of motion allows a unique investigation layer flow at very high numbers. data include mean velocities, streamwise turbulence...
Fully resolved measurements of turbulent boundary layers are reported for the Reynolds number range $Re_{\unicode[STIX]{x1D70F}}=6000{-}20\,000$ . Despite several decades research in wall-bounded turbulence there is still controversy over behaviour streamwise intensities near wall, especially at high numbers. Much it stems from uncertainty measurement due to finite spatial resolution. Conventional hot-wire anemometry limited resolution issues that cause attenuation intensity profile wall. To...
Laboratory experiments were performed on a geometrically scaled vertical-axis wind turbine model over an unprecedented range of Reynolds numbers, including and exceeding those the full-scale turbine. The study was in high-pressure environment Princeton High number Test Facility (HRTF). Utilizing highly compressed air as working fluid enabled extremely high numbers while still maintaining dynamic similarity by matching tip speed ratio (defined velocity to free stream,...
Changes in the ambient fluid temperature change calibration curve for velocity measurements taken using hot-wire anemometry. New correction methods are proposed to account effects of relatively large changes heat-transfer process and on properties. The corrections do not assume any particular correlation, they require multiple calibrations over a range temperatures. derived constant current modes operation.
A correction for streamwise Reynolds stress data acquired with insufficient spatial resolution is proposed wall-bounded flows. The method based on the attached eddy hypothesis to account filtering effects at all wall-normal positions. This analysis reveals that outside near-wall region effect scales inversely distance from wall, in contrast commonly assumed scaling viscous length scale. new formulation shown work very well taken over a wide range of numbers and wire lengths.
Results are presented on the flow field downstream of a body revolution for Reynolds numbers based model length ranging from 1.1 × 10 6 to 67 . The maximum number is more than an order magnitude larger that obtained in previous laboratory wake studies. Measurements taken intermediate at locations 3, 6, 9, 12 and 15 diameters stern midline plane. idealized submarine shape (DARPA SUBOFF), it mounted wind tunnel support shaped like semi-infinite sail. mean velocity distributions side opposite...
Abstract Five separate data sets on the mean velocity distributions in Princeton University/ONR Superpipe are used to establish best estimate for value of von Kármán’s constant flow a fully developed, hydraulically smooth pipe. The profiles were taken using Pitot tubes, conventional hot wires and nanoscale thermal anemometry probes. was found vary significantly due measurement uncertainties velocity, friction wall distance, number points included analysis. Kármán turbulent pipe is be $0.40...
Abstract Well-resolved streamwise velocity spectra are reported for smooth- and rough-wall turbulent pipe flow over a large range of Reynolds numbers. The turbulence structure far from the wall is seen to be unaffected by roughness, in accordance with Townsend’s number similarity hypothesis. Moreover, energy within region follow classical inner outer scaling behaviour. While an overlap between two scalings associated ${ k}_{x}^{- 1} $ law observed near ${R}^{+ } \approx 3000$ , behaviour...
Abstract This article reports on one component of a larger study measurement the zero-pressure-gradient turbulent flat plate boundary layer, in which detailed investigation was conducted suite corrections required for mean velocity measurements performed using Pitot tubes. In particular, shear across tube and blockage effects occur when is close proximity to wall were investigated from tubes five different diameters, two facilities, at Reynolds numbers ranging ${\mathit{Re}}_{\theta } =...
Liquid-infused surfaces present a novel, passive method of turbulent drag reduction. Inspired by the Nepenthes Pitcher Plant, liquid-infused utilize lubricating fluid trapped within structured roughness to facilitate slip at effective surface. The conceptual idea is similar that superhydrophobic surfaces, which rely on air layer, whereas use preferentially wetting liquid lubricant create localized fluid–fluid interfaces. Maintaining presence these slipping interfaces has been shown be an...
New measurements of the streamwise component turbulence intensity in a fully developed pipe flow at Reynolds numbers up to 145 000 indicate that magnitude near-wall peak is invariant with number location and magnitude. The results agree previous data have sufficient spatial resolution avoid filtering effects, but stand contrast similar obtained boundary layers, where displays prominent dependence, although its position fixed same as flow. This indicates interaction between inner outer...
Two-point hot-wire measurements of streamwise velocity were performed in the logarithmic and wake regions turbulent pipe flow for Reynolds numbers, based on diameter, ranging from 7.6 × 10 4 to 8.3 6 at four wall-normal positions with azimuthal probe separation. The correlations found be consistent presence very large-scale coherent low-wavenumber, low-momentum fluid observed previous studies wall-bounded flows independent changing number surface roughness effects. At edge layer scale...
A new model for the drag force on a two-dimensional flat plate of arbitrary porosity, oriented normal to free stream, is introduced. The an extension that introduced by Koo & James ( J. Fluid Mech. , vol. 60(3), 1973, pp. 513–538), where performance at low porosities improved including base-suction term. additional due base suction calculated implicitly using momentum theory, which makes self-contained. predictions exhibit convincing agreement with experimental observations over wide...
Gas diffusion rates in and out of superhydrophobic surfaces transitional turbulent boundary layers are observed measured at varying Reynolds numbers, pressures, dissolved gas concentrations. Results show a power-law correlation between the Sherwood friction number.
Direct numerical simulations of two superposed fluids in a channel with textured surface on the lower wall have been carried out. A parametric study varying viscosity ratio between has performed to mimic both idealised super-hydrophobic and liquid-infused surfaces assess its effect frictional, form total drag for three different geometries: longitudinal square bars, transversal bars staggered cubes. The interface is assumed be slippery streamwise spanwise directions not deformable vertical...