Journal articles: 'Reynolds Range'

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Horiguchi, Hironori, Daisuke Yumiba, Yoshinobu Tsujimoto, Masaaki Sakagami, and Shigeo Tanaka. "Reynolds Number Effect on Regenerative Pump Performance in Low Reynolds Number Range." International Journal of Fluid Machinery and Systems 1, no. 1 (August 1, 2008): 101–8. http://dx.doi.org/10.5293/ijfms.2008.1.1.101.

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Castaing, B., and Y. Gagne. "Inertial and dissipative range intermittency at high Reynolds numbers." Physica Scripta T49A (January 1, 1993): 74–76. http://dx.doi.org/10.1088/0031-8949/1993/t49a/011.

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HORIGUCHI, Hironori, Daisuke YUMIBA, Yoshinobu TSUJIMOTO, Masaaki SAKAGAMI, and Shigeo TANAKA. "Reynolds Number Effect for the Performance of Regenerative Pump in the Range of Low Reynolds Number." Transactions of the Japan Society of Mechanical Engineers Series B 73, no. 735 (2007): 2260–68. http://dx.doi.org/10.1299/kikaib.73.2260.

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FARAZMAND, M. M., N. K. R. KEVLAHAN, and B. PROTAS. "Controlling the dual cascade of two-dimensional turbulence." Journal of Fluid Mechanics 668 (November 30, 2010): 202–22. http://dx.doi.org/10.1017/s0022112010004635.

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The Kraichnan–Leith–Batchelor (KLB) theory of statistically stationary forced homogeneous isotropic two-dimensional turbulence predicts the existence of two inertial ranges: an energy inertial range with an energy spectrum scaling of k−5/3, and an enstrophy inertial range with an energy spectrum scaling of k−3. However, unlike the analogous Kolmogorov theory for three-dimensional turbulence, the scaling of the enstrophy range in the two-dimensional turbulence seems to be Reynolds-number-dependent: numerical simulations have shown that as Reynolds number tends to infinity, the enstrophy range of the energy spectrum converges to the KLB prediction, i.e. E ~ k−3. The present paper uses a novel optimal control approach to find a forcing that does produce the KLB scaling of the energy spectrum in a moderate Reynolds number flow. We show that the time–space structure of the forcing can significantly alter the scaling of the energy spectrum over inertial ranges. A careful analysis of the optimal forcing suggests that it is unlikely to be realized in nature, or by a simple numerical model.

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Qian, J. "Inertial range and the finite Reynolds number effect of turbulence." Physical Review E 55, no. 1 (January 1, 1997): 337–42. http://dx.doi.org/10.1103/physreve.55.337.

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Hollenberg, J. W. "Reynolds Number Effects on Regenerative Pump Performance." Journal of Engineering for Industry 109, no. 4 (November 1, 1987): 392–95. http://dx.doi.org/10.1115/1.3187144.

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Reynolds number effects on the performance of a conventional design regenerative pump were investigated, using glycerine-water mixtures, between an impeller tip speed Reynolds number, RT, of 5.0×103 (all glycerine) and 1.6×106 (all water). Results show that the maximum efficiency, nm, can be expressed in terms of an output to loss ratio, nm/1−nm, which varies as RT0.203 for 2.0×104 < RT < 1.6×106 and as RT1.156 for RT < 2.0×104. These results are consistent with efficiency behavior reported in similar investigations on other types of turbomachines. Further, the design point flow coefficient increased over the range of Reynolds number investigated, while the design point head coefficient exhibited a maximum within this range. In addition, marked departure from scaling behavior occurred in the lower Reynolds number range. Finally, the correlation among torque coefficient, head coefficient, and flow coefficient previously established by the author was further verified and followed scaling behavior for the higher Reynolds number range.

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Michna, Jan, and Krzysztof Rogowski. "Numerical Study of the Effect of the Reynolds Number and the Turbulence Intensity on the Performance of the NACA 0018 Airfoil at the Low Reynolds Number Regime." Processes 10, no. 5 (May 18, 2022): 1004. http://dx.doi.org/10.3390/pr10051004.

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In recent years, there has been an increased interest in the old NACA four-digit series when designing wind turbines or small aircraft. One of the airfoils frequently used for this purpose is the NACA 0018 profile. However, since 1933, for over 70 years, almost no new experimental studies of this profile have been carried out to investigate its performance in the regime of small and medium Reynolds numbers as well as for various turbulence parameters. This paper discusses the effect of the Reynolds number and the turbulence intensity on the lift and drag coefficients of the NACA 0018 airfoil under the low Reynolds number regime. The research was carried out for the range of Reynolds numbers from 50,000 to 200,000 and for the range of turbulence intensity on the airfoil from 0.01% to 0.5%. Moreover, the tests were carried out for the range of angles of attack from 0 to 10 degrees. The uncalibrated γ−Reθ transition turbulence model was used for the analysis. Our research has shown that airfoil performance is largely dependent on the Reynolds number and less on the turbulence intensity. For this range of Reynolds numbers, the characteristic of the lift coefficient is not linear and cannot be analyzed using a single aerodynamic derivative as for large Reynolds numbers. The largest differences in both aerodynamic coefficients are observed for the Reynolds number of 50,000.

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Squire, L. C. "The accuracy of flat plate, turbulent skin friction at supersonic speeds." Aeronautical Journal 104, no. 1036 (June 2000): 257–63. http://dx.doi.org/10.1017/s0001924000091570.

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Abstract This paper presents a comparison of turbulent skin-friction coefficients measured by floating element balances in zero pressure gradient conditions for a wide range of Mach numbers and Reynolds numbers. From these comparisons it is clear that although a large number of measurements have been made it is impossible to use these measurements to find the skin-friction coefficient for a given Mach number and Reynolds number to an accuracy of better than ±2 to 3%. This estimate of accuracy applies only to the range of Mach numbers and Reynolds within which there are a reasonable number of measurements to compare. Outside this range, say for Reynolds numbers based on momentum thickness greater than 40,000 and Mach numbers greater than 2 the uncertainty is greater.

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Ramarajan, V., and S. Soundranayagam. "Scale Effects in a Mixed Flow Pump: Part 1." Proceedings of the Institution of Mechanical Engineers, Part A: Power and Process Engineering 200, no. 3 (August 1986): 173–79. http://dx.doi.org/10.1243/pime_proc_1986_200_024_02.

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The variation of efficiency and losses over a range of Reynolds numbers has been measured for a mixed flow pump of specific speed 118 r/min for a number of points covering its operating range. The losses have been separated into those of the impeller and volute. The efficiency is seen to show a steady rise throughout the experimental range in comparison with published results for centrifugal pumps which flatten out at higher Reynolds numbers. A distinct hump is seen in many of the efficiency variation curves as well as in the variation of head with Reynolds number. The hump in the efficiency curves seems to be connected with transition to a roughness dominated regime while that in the head variation appears to be connected to changes in circulation. They both occur at different Reynolds numbers and are unconnected with each other. The frictional component of the losses in the volute is small and the losses there seem to be largely independent of Reynolds number.

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Che Sidik, Nor Azwadi, and Siti Aisyah Razali. "Stability Condition for Single-Relaxation Time Isothermal Lattice Boltzmann Formulation." Applied Mechanics and Materials 695 (November 2014): 667–70. http://dx.doi.org/10.4028/www.scientific.net/amm.695.667.

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In this present research, the Lattice Boltzmann method has been used to determine the stability condition of the single relaxation time. The range of Reynolds number is 100,400 and 1000. Meanwhile, the range of mesh size is varying between 31 to 251. The results show that the increase in both mesh size and Reynolds number give an effect on deviation percentages. The deviation percentages for all mesh and Reynolds number also presented.

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SMYTH, WILLIAM D. "Dissipation-range geometry and scalar spectra in sheared stratified turbulence." Journal of Fluid Mechanics 401 (December 25, 1999): 209–42. http://dx.doi.org/10.1017/s0022112099006734.

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Direct numerical simulations of turbulence resulting from Kelvin–Helmholtz instability in stratified shear flow are used to examine the geometry of the dissipation range in a variety of flow regimes. As the buoyancy and shear Reynolds numbers that quantify the degree of isotropy in the dissipation range increase, alignment statistics evolve from those characteristic of parallel shear flow to those found previously in studies of stationary, isotropic, homogeneous turbulence (e.g. Ashurst et al. 1987; She et al. 1991; Tsinober et al. 1992). The analysis yields a limiting value for the mean compression rate of scalar gradients that is expected to be characteristic of all turbulent flows at sufficiently high Reynolds number.My main focus is the value of the constant q that appears in both the Batchelor (1959) and Kraichnan (1968) theoretical forms for the passive scalar spectrum. Taking account of the effects of time-dependent strain, I propose a revised estimate of q, denoted qe, which appears to agree with spectral shapes derived from simulations and observations better than do previous theoretical estimates. The revised estimate is qe = 7.3±4, and is expected to be valid whenever the buoyancy Reynolds number exceeds O(102). The Kraichnan (1968) spectral form, in which effects of intermittency are accounted for, provides a better fit to the DNS results than does the Batchelor (1959) form.

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Adachi, Tsutomu, Hiroyuki Maeda, Masamitsu Shiono, Tetsuo Ozaki, Kazuo Matsuuchi, and Tatsuo Kawai. "Drag Reduction of Circular Cylinder in the High-Reynolds-Number Range." Transactions of the Japan Society of Mechanical Engineers Series B 59, no. 558 (1993): 342–48. http://dx.doi.org/10.1299/kikaib.59.342.

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13

Vry, J. K. "Boron-free kornerupine from the Reynolds Range, Arunta Block, central Australia." Mineralogical Magazine 58, no. 390 (March 1994): 27–37. http://dx.doi.org/10.1180/minmag.1994.058.390.03.

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AbstractNearly boron-free kornerupine is locally abundant in pods or lenses of coarse-grained, non-foliated, Mg- and Al-rich rocks that occur at high metamorphic grades in early Proterozoic metapelitic rocks from the Reynolds Range, Northern Territory, Australia. This is the third reported occurrence of boron-free kornerupine worldwide. The samples consist almost entirely of coarse-grained kornerupine and its breakdown products sapphirine, cordierite, and gedrite or orthopyroxene. The kornerupine contains only 0.45 wt.% B2O3, corresponding to 0.098 B atoms per 22 (O, OH), and closely approximates 11:10:11 in terms of molar ratios of (MgO + FeOtotal):Al2O3:SiO2, with XMg = Mg/(Mg + Fetotal) = 0.874. The unusual textures and bulk compositions of the rocks in the pods are interpreted to have resulted from metasomatism and high-grade metamorphism (750 to 800° and ∼ 4.5 kbar) of precursors that may have included sedimentary Mg-rich clays. Rocks containing boron-poor, and relatively boronrich kornerupine (2.18 wt.% B2O3; XMg = 0.892) are separated in outcrop by as little as 10 m of the foliated cordierite-quartzite country rock and other rock types, suggesting that the compositions or amounts of the metasomatic fluids varied on a local scale.

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Kato, Yoshihito, Noboru Kamei, Yutaka Tada, Noriyuki Kato, Tomoho Kato, Tatsuhiko Ibuki, Haruki Furukawa, and Yuichiro Nagatsu. "Power Consumption of Anchor Impeller over Wide Range of Reynolds Number." KAGAKU KOGAKU RONBUNSHU 37, no. 1 (2011): 19–21. http://dx.doi.org/10.1252/kakoronbunshu.37.19.

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Michna, Gregory J., Anthony M. Jacobi, and Rodney L. Burton. "An Experimental Study of the Friction Factor and Mass Transfer Performance of an Offset-Strip Fin Array at Very High Reynolds Numbers." Journal of Heat Transfer 129, no. 9 (January 22, 2007): 1134–40. http://dx.doi.org/10.1115/1.2739599.

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Thermal-hydraulic performance data for offset-strip fin arrays are readily available in the range Re<10,000. However, in emerging applications in automotive and aerospace systems, where fan power is not a constraint and compactness is important, it may be desirable to operate offset-strip fin heat exchangers at very high Reynolds numbers. In this paper, friction factor and mass transfer performance of an offset-strip fin array at Reynolds numbers between 10,000 and 120,000 are characterized. A scale-model, eight-column fin array is used in pressure drop and naphthalene sublimation experiments, and the data are compared to predictions of performance given by available analytical models and extrapolations of the best available correlations. The friction factor data follow the correlation-predicted trend of decreasing monotonically as the Reynolds number is increased to 20,000. However, at higher Reynolds numbers, the friction factor increases as the Reynolds number increases and local maxima are observed in the data. Over the range investigated, the modified Colburn j factor decreases monotonically as the Reynolds number increases. For Reynolds numbers in the range 10,000<Re<120,000, well beyond that covered by state-of-the-art correlations, both the friction factor and Colburn j factor are roughly twice that predicted by extrapolating the best available correlations. The higher-than-predicted Colburn j factor at very high Reynolds numbers is encouraging for the use of offset-strip fin heat exchangers in emerging applications where compactness is of high importance.

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Kamoji, M. A., S. B. Kedare, and S. V. Prabhu. "Experimental Investigations on the Effect of Overlap Ratio and Blade Edge Conditions on the Performance of Conventional Savonius Rotor." Wind Engineering 32, no. 2 (March 2008): 163–78. http://dx.doi.org/10.1260/030952408784815826.

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The torque of a conventional Savonius rotor is studied experimentally for overlap ratio from 0.10 to 0.70, blade edge condition (flat and round) and the change in Reynolds number. The results indicate that the coefficient of static torque improves marginally for round edged rotors for rotor angles up to 45°. The coefficient of static torque decreases as the overlap ratio is increased to 0.70 from 0.50 and is independent of the Reynolds numbers studied in the range between 120000 to 200000. Wind tunnel blockage ratio is studied. The power coefficient increases with the increase in the Reynolds number, whereas the coefficient of static torque is independent of the Reynolds number in the range studied. The coefficient of power, torque coefficient and coefficient static torque are independent of blockage ratios at a given Reynolds number.

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Wang, Na, and Chao Gao. "Variable Reynolds Number Experimental Study on Aerodynamic Characteristic of Supercritical Airfoil RAE2822." Applied Mechanics and Materials 420 (September 2013): 42–46. http://dx.doi.org/10.4028/www.scientific.net/amm.420.42.

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An experimental study of pressure distributions over RAE2822 airfoil in the two-dimensional test section 0.8×0.4 meter of a transonic wind tunnel which is the first pressruized continuous wind tunnel in China is presented. This paper in order to further study the influence of the dynamic of continuous changes Reynolds number at Mach number is 0.66 and 0.80, and the attack angle is from-2 degree to 10 degree, and especially the Reynolds number range from3.0×106to 12×106. The study is focalized on the subsonic range of flow conditions with separation and shock wave in the boundary layer. The influence of pressure distribution and pressure coefficient and moment coefficient caused by Reynolds number increasing are analyzed and discussed. The conclusions showed that the pressure distribution of the lower surface of the airfoil get the influence of the Reynolds number is negligible. The Reynolds number impact on the pressure distribution is faintness at Ma=0.66. Reynolds number increases affect the airfoil central and trailing edge pressure. As the Reynolds number increases, the CL curve move and the gradient increasing. The moment coefficient decreased as the Reynolds number increasing. The CL curve with Cd curve moves left as Reynolds number increasing.

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18

Ahmed, G. Refai, and M. M. Yovanovich. "Experimental Study of Forced Convection From Isothermal Circular and Square Cylinders and Toroids." Journal of Heat Transfer 119, no. 1 (February 1, 1997): 70–79. http://dx.doi.org/10.1115/1.2824102.

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Experimental studies of forced convection heat transfer from different body shapes were conducted to determine the effects of Reynolds number and different characteristic body lengths on the area-averaged Nusselt number. Although the bodies differed significantly in their shapes, they had approximately the same total surface area, A = 11,304 mm2 ± 5%. This ensured that for a given free stream velocity and total heat transfer rate all bodies had similar trends for the relationship of Nusselt and Reynolds numbers. The experimental program range was conducted in the Reynolds number range 104≤ReA≤105 and Prandtl number 0.71. Finally, the empirical models for forced convection heat transfer were developed. These empirical models were valid for a wide range of Reynolds numbers 0≤ReA≤105. The present experimental correlations were compared with available correlation equations and experimental data. These comparisons show very good agreement.

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Buckholz, R. H. "Effects of Power—Law, Non-Newtonian Lubricants on Load Capacity and Friction for Plane Slider Bearings." Journal of Tribology 108, no. 1 (January 1, 1986): 86–91. http://dx.doi.org/10.1115/1.3261149.

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The lubrication of a conventional, finite width plane bearing, using a power-law, non-Newtonian lubricant, is studied. The basic assumptions in this analysis are: thin fluid-film, no thermal effects, and a modified Reynolds’ equation for small bearing aspect ratios. Results from this study include bearing pressure, load, and friction formulas. Similar results for the not-so-small bearing aspect ratios are found via an Euler-Lagrange equation. This Euler-Lagrange equation is derived from the optimization integral for the modified Reynolds’ equation. Approximate solutions to the modified Reynolds’ equation and to the Euler-Lagrange equation are contrasted with numerical solutions for the modified Reynolds equation. Bearing aspect ratios in the range 0.1 to 0.6, clearance ratios in the range 1.2 to 4.0, and non-Newtonian power-law index in the range 0.4 to 1.0 are considered.

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Raza, Wasim, Shakhawat Hossain, and Kwang-Yong Kim. "A Review of Passive Micromixers with a Comparative Analysis." Micromachines 11, no. 5 (April 27, 2020): 455. http://dx.doi.org/10.3390/mi11050455.

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A wide range of existing passive micromixers are reviewed, and quantitative analyses of ten typical passive micromixers were performed to compare their mixing indices, pressure drops, and mixing costs under the same axial length and flow conditions across a wide Reynolds number range of 0.01–120. The tested micromixers were selected from five types of micromixer designs. The analyses of flow and mixing were performed using continuity, Navier-Stokes and convection-diffusion equations. The results of the comparative analysis were presented for three different Reynolds number ranges: low-Re (Re ≤ 1), intermediate-Re (1 < Re ≤ 40), and high-Re (Re > 40) ranges, where the mixing mechanisms are different. The results show a two-dimensional micromixer of Tesla structure is recommended in the intermediate- and high-Re ranges, while two three-dimensional micromixers with two layers are recommended in the low-Re range due to their excellent mixing performance.

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21

Schröder, Tilman, Sebastian Schuster, and Dieter Brillert. "Experimental Investigation of Centrifugal Flow in Rotor–Stator Cavities at High Reynolds Numbers >108." International Journal of Turbomachinery, Propulsion and Power 6, no. 2 (May 26, 2021): 13. http://dx.doi.org/10.3390/ijtpp6020013.

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The designers of radial turbomachinery need detailed information on the impact of the side chamber flow on axial thrust and torque. A previous paper investigated centripetal flow through narrow rotor–stator cavities and compared axial thrust, rotor torque and radial pressure distribution to the case without through-flow. Consequently, this paper extends the investigated range to centrifugal through-flow as it may occur in the hub side chamber of radial turbomachinery. The chosen operating conditions are representative of high-pressure centrifugal compressors used in, for example, carbon capture and storage applications as well as hydrogen compression. To date, only the Reynolds number range up to Re=2·107 has been investigated for centrifugal through-flow. This paper extends the range to Reynolds numbers of Re=2·108 and reports results of experimental and numerical investigations. It focuses on the radial pressure distribution in the rotor–stator cavity and shows the influence of the Reynolds number, cavity width and centrifugal mass flow rate. It therefore extends the range of available valid data that can be used to design radial turbomachinery. Additionally, this analysis compares the results to data and models from scientific literature, showing that in the higher Reynolds number range, a new correlation is required. Finally, the analysis of velocity profiles and wall shear delineates the switch from purely radial outflow in the cavity to outflow on the rotor and inflow on the stator at high Reynolds numbers in comparison to the results reported by others for Reynolds numbers up to Re=2·107.

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Jovanovic´, J., I. Otic´, and P. Bradshaw. "On the Anisotropy of Axisymmetric Strained Turbulence in the Dissipation Range." Journal of Fluids Engineering 125, no. 3 (May 1, 2003): 401–13. http://dx.doi.org/10.1115/1.1568355.

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Partition of the stress dissipation has been studied in an axisymmetric strained flow field to assess the possible existence of local isotropy for turbulence at small scales. This is a simple flow to study because the axes of anisotropy of the Reynolds stresses and of the dissipation tensor are aligned. Using invariant theory, the relationship between the stress and dissipation tensors was derived, satisfying restrictions for the limiting states of turbulence and the assumed behavior for large Reynolds number and small anisotropy. The role of the anisotropy in constraining models for the turbulent dissipation rate and the pressure-strain correlations is discussed. Comparisons of the resulting closure with experimental data for several axisymmetric flows are good within the limitations of the data.

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GOTOH, TOSHIYUKI, and ROBERT S. ROGALLO. "Intermittency and scaling of pressure at small scales in forced isotropic turbulence." Journal of Fluid Mechanics 396 (October 10, 1999): 257–85. http://dx.doi.org/10.1017/s0022112099005972.

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The intermittency of pressure and pressure gradient in stationary isotropic turbulence at low to moderate Reynolds numbers is studied by direct numerical simulation (DNS) and theoretically. The energy spectra scale in Kolmogorov units as required by the universal-equilibrium hypothesis, but the pressure spectra do not. It is found that the variances of the pressure and pressure gradient are larger than those computed using the Gaussian approximation for the fourth-order moments of velocity, and that the variance of the pressure gradient, normalized by Kolmogorov units, increases roughly as [Rscr ]1/2λ, where [Rscr ]λ is the Taylor microscale Reynolds number. A theoretical explanation of the Reynolds number dependence is presented which assumes that the small-scale pressure field is driven by coherent small-scale vorticity–strain domains. The variance of the pressure gradient given by the model is the product of the variance of ui,juj,i, the source term of the Poisson equation for pressure, and the square of an effective length of the small-scale coherent vorticity–strain structures. This length can be expressed in terms of the Taylor and Kolmogorov microscales, and the ratio between them gives the observed Reynolds number dependence. Formal asymptotic matching of the spectral scaling observed at small scales in the DNS with the classical scaling at large scales suggests that at high Reynolds numbers the pressure spectrum in these forced flows consists of three scaling ranges which are joined by two inertial ranges, the classical k−7/3 range and a k−5/3 range at smaller scale. It is not possible, within the classical Kolmogorov theory, to determine the length scale at which the inertial range transition occurs because information beyond the energy dissipation rate is required.

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Om, Nur Irmawati, and Hussein A. Mohammed. "Numerical Study of Mixed Convection through Horizontal Duct Utilizing Al₂O₃." Applied Mechanics and Materials 819 (January 2016): 111–16. http://dx.doi.org/10.4028/www.scientific.net/amm.819.111.

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In the present study, mixed convection in a horizontal rectangular duct using Al2O3 is numerically investigated. The effects of different Rayleigh number, Reynolds number and radiation on flow and heat transfer characteristics were studied in detail. This study covers Rayleigh number in the range of 2 106 ≤ Ra ≤ 2 107 and Reynolds number in the range of 100 ≤ Re ≤ 1100. Results reveal that the Nusselt number increases as Reynolds and Rayleigh numbers increase. It was also found that the dimensionless temperature distribution increases as Rayleigh number increases.

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BOUHAIRIE, SALEM, and VINCENT H. CHU. "Two-dimensional simulation of unsteady heat transfer from a circular cylinder in crossflow." Journal of Fluid Mechanics 570 (January 3, 2007): 177–215. http://dx.doi.org/10.1017/s0022112006002941.

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The heat transfer from the surface of a circular cylinder into a crossflow has been computed using a two-dimensional model, for a range of Reynolds numbers from Re=200 to 15550. The boundary-layer separation, the local and overall heat-transfer rates, the eddy- and flare-detachment frequencies and the width of the flares were determined from the numerical simulations. In this range of Reynolds numbers, the heat-transfer process is unsteady and is characterized by a viscous length scale that is inversely proportional to the square root of the Reynolds number. To ensure uniform numerical accuracy for all Reynolds numbers, the dimensions of the computational mesh were selected in proportion to this viscous length scale. The small scales were resolved by at least three nodes within the boundary layers. The frequency of the heat flares increases, and the width of each flare decreases, with the Reynolds number, in proportion to the viscous time and length scales. Despite the presence of three-dimensional structures for the range of Reynolds numbers considered, the two-dimensional model captures the unsteady processes and produced results that were consistent with the available experimental data. It correctly simulated the overall, the front-stagnation and the back-to-total heat-transfer rates.

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Samie, M., I. Marusic, N. Hutchins, M. K. Fu, Y. Fan, M. Hultmark, and A. J. Smits. "Fully resolved measurements of turbulent boundary layer flows up to." Journal of Fluid Mechanics 851 (July 20, 2018): 391–415. http://dx.doi.org/10.1017/jfm.2018.508.

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Fully resolved measurements of turbulent boundary layers are reported for the Reynolds number range $Re_{\unicode[STIX]{x1D70F}}=6000{-}20\,000$. Despite several decades of research in wall-bounded turbulence there is still controversy over the behaviour of streamwise turbulence intensities near the wall, especially at high Reynolds numbers. Much of it stems from the uncertainty in measurement due to finite spatial resolution. Conventional hot-wire anemometry is limited for high Reynolds number measurements due to limited spatial resolution issues that cause attenuation in the streamwise turbulence intensity profile near the wall. To address this issue we use the nano-scale thermal anemometry probe (NSTAP), developed at Princeton University to conduct velocity measurements in the high Reynolds number boundary layer facility at the University of Melbourne. The NSTAP has a sensing length almost one order of magnitude smaller than conventional hot-wires. This enables us to acquire fully resolved velocity measurements of turbulent boundary layers up to $Re_{\unicode[STIX]{x1D70F}}=20\,000$. Results show that in the near-wall region, the viscous-scaled streamwise turbulence intensity grows with $Re_{\unicode[STIX]{x1D70F}}$ in the Reynolds number range of the experiments. A second outer peak in the streamwise turbulence intensity is also shown to emerge at the highest Reynolds numbers. Moreover, the energy spectra in the near-wall region show excellent inner scaling over the small to moderate wavelength range, followed by a large-scale influence that increases with Reynolds number. Outer scaling in the outer region is found to collapse the energy spectra over high wavelengths across various Reynolds numbers.

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27

Baughn, J. W., M. A. Hoffman, R. K. Takahashi, and Daehee Lee. "Heat Transfer Downstream of an Abrupt Expansion in the Transition Reynolds Number Regime." Journal of Heat Transfer 109, no. 1 (February 1, 1987): 37–42. http://dx.doi.org/10.1115/1.3248064.

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The heat transfer downstream of an axisymmetric abrupt expansion in a pipe in the transition Reynolds number regime has been investigated experimentally. In these experiments the wall of the downstream pipe was heated to give a constant heat flux into the air flow. The ratio of the upstream to downstream pipe diameters was 0.8 and the downstream Reynolds number ranged from 1420 to 8060. Within a narrow range of Reynolds numbers, around 5000, the position of the maximum Nusselt number was found to shift considerably. This interesting behavior may be associated with the flow instabilities in sudden expansions which have been observed by others.

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Ebnereza, Eshaq, Kamran Hassani, Mahmoud Seraj, and Katayoun Gohari Moghaddam. "Shape optimization of a split-and-recombine micromixer by the local energy dissipation rate." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 234, no. 3 (March 16, 2020): 243–51. http://dx.doi.org/10.1177/0954408920910588.

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A passive split-and-recombine micromixer was developed based on the concept of lamellar structure and advection mixing type for a serpentine structure. The flow patterns and mixing performance were analyzed using numerical simulation in Reynolds number range of 10≤ Reynolds ≤170. Two design variables, defining the shape of the split-and-recombine branch, were optimized by the local energy dissipation rate as the objective function. The reduction of computation time and the absence of numerical diffusion were the advantages of using the energy dissipation rate as the objective function. At each Reynolds number, 64 sample data was generated on the design space uniformly. Then a model was used based on the Radial basis neural network for the prediction of the objective function. The optimum values of the design variables within the constraint range were found on the response surface. The optimization study was performed at five Reynolds numbers of 10, 50, 90, 130, 170 and the mixing index was improved 0.156, 0.298, 0.417, 0.506, and 0.57, respectively. The effect of design variables on the objective function and the concentration pattern was presented and analyzed. Finally, the mixing characteristic of the split-and-recombine micromixer was studied in a wide range of Reynolds number and the flow was categorized to stratify and show the vortex regime based on the Reynolds number. The optimized split-and-recombine micromixer could be integrated by any system depending on the desired velocity and Reynolds number.

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Nickels, T. B., I. Marusic, S. Hafez, N. Hutchins, and M. S. Chong. "Some predictions of the attached eddy model for a high Reynolds number boundary layer." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 365, no. 1852 (January 16, 2007): 807–22. http://dx.doi.org/10.1098/rsta.2006.1950.

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Many flows of practical interest occur at high Reynolds number, at which the flow in most of the boundary layer is turbulent, showing apparently random fluctuations in velocity across a wide range of scales. The range of scales over which these fluctuations occur increases with the Reynolds number and hence high Reynolds number flows are difficult to compute or predict. In this paper, we discuss the structure of these flows and describe a physical model, based on the attached eddy hypothesis, which makes predictions for the statistical properties of these flows and their variation with Reynolds number. The predictions are shown to compare well with the results from recent experiments in a new purpose-built high Reynolds number facility. The model is also shown to provide a clear physical explanation for the trends in the data. The limits of applicability of the model are also discussed.

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Mostafa, Mahmoud, Radwan Kamal, and Mohamed Gobran. "Flow and heat transfer characteristics around an elliptic cylinder placed in front of a curved plate." Thermal Science 18, no. 2 (2014): 465–78. http://dx.doi.org/10.2298/tsci120307054m.

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An experimental investigation has been conducted to clarify heat transfer characteristics and flow behaviors around an elliptic cylinder. Also, flow visualization was carried out to clarify the flow patterns around the cylinder. The elliptic cylinder examined has an axis ratio of 1:2.17, was placed in the focus of parabolic plate. The test fluid is air and the Reynolds number based on the major axis length, c, ranged from 5 x 103 to 3 x 104. The angle of attack (?) was changed from 0? to 90? at 15? interval. It is found that the pressure distribution, form drag, location of separation point, and heat transfer coefficient depend strongly upon the angle of attack. Over the Reynolds number range examined, the mean heat transfer coefficient is at its highest at ? = 60? - 90?. The values of heat transfer coefficient in the case of free cylinder are higher than those for cylinder/plate combination at all angles of attack and Reynolds number range examined.

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31

Lee, Kee Quen, Abu Aminudin, and Muhamad Pauziah. "Investigation of Wide Range of Flow around Circular Cylinder Using Turbulence Model." Advanced Materials Research 664 (February 2013): 878–83. http://dx.doi.org/10.4028/www.scientific.net/amr.664.878.

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The purpose of present study is to identify the possibility of predicting the physical features of circular cylinder in two dimensional for a wide range of Reynolds number using a modified turbulence model. The modification is focused on the turbulence length and intensity. The drag coefficient and the Strouhal number were calculated and compared with the existing experimental data. The contour of vorticity and pressure gradient were also presented. Although variation up to 159% was noted in the drag coefficient, it was just on a particular Reynolds number.The simulated outputs of Strouhal number, pressure coefficient and vorticity contour indicated reasonable agreement with the experimental data. The modified turbulence model has showed potential in simulating the flow around the circular cylinder.

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32

Nam, Ho-Yun, Jong-Man Kim, Kyung-Won Seo, and Seok-Ki Choi. "Development of an Experimental Correlation for a Pressure Loss at a Side Orifice." Journal of Fluids Engineering 127, no. 2 (October 27, 2004): 388–92. http://dx.doi.org/10.1115/1.1881694.

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An experimental study has been carried out to measure the pressure loss at the side orifice of a liquid metal reactor fuel assembly. The characteristics of the pressure loss at the side orifice are investigated using the experimental data measured from 17 different types of side orifices that have different geometric shapes, dimensions, and arrangements of nozzles, and a correlation that covers the whole flow range by one equation is developed. The error range of the correlation is within ±10%, and most of the errors occurred in a region where the Reynolds number is small. The range of Reynolds numbers based on the hydraulic diameter of the orifice is 2000–350,000. It is found that the geometric factor is the most important parameter for the pressure loss when the Reynolds number is >30,000. As the Reynolds number becomes smaller, its effect becomes larger, and when the Reynolds number is small, it is the most important parameter for the pressure loss at the side orifices. The measured data shows a trend that the pressure loss coefficient increases as the number of orifices increases, and the effect of the longitudinal arrangement is small.

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Dandy, David S., and Harry A. Dwyer. "A sphere in shear flow at finite Reynolds number: effect of shear on particle lift, drag, and heat transfer." Journal of Fluid Mechanics 216 (July 1990): 381–410. http://dx.doi.org/10.1017/s0022112090000477.

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Three-dimensional numerical solutions have been obtained for steady, linear shear flow past a fixed, heated spherical particle over a wide range of Reynolds number (0.1 [les ] R [les ] 100) and dimensionless shear rates (0.005 [les ] α [les ] 0.4). The results indicate that at a fixed shear rate, the dimensionless lift coefficient is approximately constant over a wide range of intermediate Reynolds numbers, and the drag coefficient also remains constant when normalized by the known values of drag for a sphere in uniform flow. At lower values of the Reynolds number, the lift and drag coefficients increase sharply with decreasing R, with the lift coefficient being directly proportional to R−½. For the range of shear rates studied here, the rate of heat transfer to the particle surface was found to depend only on the Reynolds number, that is, it was insensitive to the shear rate. The dimensionless rate of heat transfer, the Nussel number Nu, was seen to increase monotonically with R.

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PEARSON, B. R., and R. A. ANTONIA. "Reynolds-number dependence of turbulent velocity and pressure increments." Journal of Fluid Mechanics 444 (September 25, 2001): 343–82. http://dx.doi.org/10.1017/s0022112001005511.

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The main focus is the Reynolds number dependence of Kolmogorov normalized low-order moments of longitudinal and transverse velocity increments. The velocity increments are obtained in a large number of flows and over a wide range (40–4250) of the Taylor microscale Reynolds number Rλ. The Rλ dependence is examined for values of the separation, r, in the dissipative range, inertial range and in excess of the integral length scale. In each range, the Kolmogorov-normalized moments of longitudinal and transverse velocity increments increase with Rλ. The scaling exponents of both longitudinal and transverse velocity increments increase with Rλ, the increase being more significant for the latter than the former. As Rλ increases, the inequality between scaling exponents of longitudinal and transverse velocity increments diminishes, reflecting a reduced influence from the large-scale anisotropy or the mean shear on inertial range scales. At sufficiently large Rλ, inertial range exponents for the second-order moment of the pressure increment follow more closely those for the fourth-order moments of transverse velocity increments than the fourth-order moments of longitudinal velocity increments. Comparison with DNS data indicates that the magnitude and Rλ dependence of the mean square pressure gradient, based on the joint-Gaussian approximation, is incorrect. The validity of this approximation improves as r increases; when r exceeds the integral length scale, the Rλ dependence of the second-order pressure structure functions is in reasonable agreement with the result originally given by Batchelor (1951).

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Wang, M. R., D. Y. Huang, and Y. C. Liu. "Droplet Dynamics Near the Wall in a Vertical Rectangular Duct." Journal of Fluids Engineering 116, no. 2 (June 1, 1994): 349–53. http://dx.doi.org/10.1115/1.2910279.

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Measurements of the droplet behavior near the wall in a vertical rectangular duct were conducted by a phase Doppler particle analyzer (PDPA). The test Reynolds number and drop size range is from 18,500 to 89,300 and from 5 μm to 110 μm, respectively. Results show that the negative slip-velocity of the drops near the free-stream region normally results in the reversed slip-velocity phenomenon in the boundary layer region. No negative slip-velocity of all drops are discovered for Reynolds number less than 38,300. This indicates no reversed slip-velocity phenomenon for the test drop size range under low Reynolds number conditions. However, when the Reynolds number is over 38,300, the free-stream slip-velocity of the bigger drops becomes negative. It is found that the negative slip-velocity and, hence, the reversed slip-velocity phenomenon may take place for drop size larger than 52 μm to 90 μm depending on the flow Reynolds number.

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Kadambi, V., E. K. Levy, and S. Neti. "Heat Transfer and Pressure Drop in a Helically Coiled Rectangular Duct." Journal of Heat Transfer 108, no. 2 (May 1, 1986): 343–49. http://dx.doi.org/10.1115/1.3246927.

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The present paper deals with experiments using air in three helically coiled rectangular ducts of mean diameters 12.7 cm, 17.8 cm, and 22.8 cm, respectively, made of rectangular wave-guide tubing of dimensions 1.27 cm × 0.64 cm. Pressure variations observed around the ducts were qualitatively in agreement with the expectations for secondary flow. The friction factors change gradually with increasing Reynolds numbers over the range 1200–10,000 without exhibiting a sudden transition from laminar flow to turbulence. At all Reynolds numbers, these are higher than those for a straight duct by 20–100 percent. The heat transfer coefficient is also higher than that for straight ducts ranging between 20–300 percent, depending on the Reynolds number. The largest increases are seen in the Reynolds number range 1200–2500.

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Oliver, D. L. R., and J. N. Chung. "Flow about a fluid sphere at low to moderate Reynolds numbers." Journal of Fluid Mechanics 177 (April 1987): 1–18. http://dx.doi.org/10.1017/s002211208700082x.

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The steady-state equations of motion are solved for a fluid sphere translating in a quiescent medium. A semi-analytical series truncation method is employed in conjunction with a cubic finite-element scheme. The range of Reynolds numbers investigated is from 0.5 to 50. The range of viscosity ratios is from 0 (gas bubble) to 107 (solid sphere). The flow structure and the drag coefficients agree closely with the limited available experimental measurements and also compare favourably with published finite-difference solutions. The strength of the internal circulation was found to increase with increasing Reynolds number. The flow patterns and the drag coefficient show little variation with the interior Reynolds number. Based on the numerical results, predictive equations for drag coefficients are recommended for both moderate- and low-Reynolds-number flows.

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Benton, Stuart I., and Miguel R. Visbal. "Extending the Reynolds Number Range of High-Frequency Control of Dynamic Stall." AIAA Journal 57, no. 7 (July 2019): 2675–81. http://dx.doi.org/10.2514/1.j058324.

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39

Kogiso, Nozomu, Tomoyoshi Utsumi, and Yoshisada Murotsu. "Shape Optimum Design of Propeller Blade Operating in Low Reynolds Number Range." JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 50, no. 586 (2002): 458–65. http://dx.doi.org/10.2322/jjsass.50.458.

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40

Viktorov, Vladimir, Md Mahmud, and Carmen Visconte. "Comparative Analysis of Passive Micromixers at a Wide Range of Reynolds Numbers." Micromachines 6, no. 8 (August 18, 2015): 1166–79. http://dx.doi.org/10.3390/mi6081166.

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41

Aniskin, V. M., A. A. Maslov, and S. G. Mironov. "Flows of Supersonic Underexpanded Jets on the Range of Moderate Reynolds Numbers." Fluid Dynamics 53, no. 1 (January 2018): 1–8. http://dx.doi.org/10.1134/s0015462818010020.

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42

Chang, Yin, and Jeannette Yen. "Swimming in the Intermediate Reynolds Range: Kinematics of the Pteropod Limacina helicina." Integrative and Comparative Biology 52, no. 5 (September 16, 2012): 597–615. http://dx.doi.org/10.1093/icb/ics113.

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43

Kumar, Vimal, Vaibhav Shirke, and K. D. P. Nigam. "Performance of Kenics static mixer over a wide range of Reynolds number." Chemical Engineering Journal 139, no. 2 (June 2008): 284–95. http://dx.doi.org/10.1016/j.cej.2007.07.101.

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44

Cartwright, I., I. Buick, and J. Vry. "The time-integrated history of crustal fluid flow: Reynolds Range, central Australia." Journal of Geochemical Exploration 69-70 (June 2000): 353–57. http://dx.doi.org/10.1016/s0375-6742(00)00091-1.

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45

Cartwright, I., I. S. Buick, D. A. Foster, and D. D. Lambert. "Alice Springs age shear zones from the southeastern Reynolds Range, central Australia." Australian Journal of Earth Sciences 46, no. 3 (June 1999): 355–63. http://dx.doi.org/10.1046/j.1440-0952.1999.00710.x.

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CARTWRIGHT, I., and I. S. BUICK. "Channelled fluid infiltration and variation in permeability in Reynolds Range marbles, Australia." Journal of the Geological Society 151, no. 4 (July 1994): 583–86. http://dx.doi.org/10.1144/gsjgs.151.4.0583.

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47

Zubkov, V. G. "Mathematical boundary-layer model for a wide range of turbulent Reynolds numbers." Journal of Engineering Physics 48, no. 5 (May 1985): 541–47. http://dx.doi.org/10.1007/bf01840718.

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48

Dai, R. X., Q. Dong, and A. Z. Szeri. "Approximations in Hydrodynamic Lubrication." Journal of Tribology 114, no. 1 (January 1, 1992): 14–25. http://dx.doi.org/10.1115/1.2920853.

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In this numerical study of the approximations that led Reynolds to the formulation of classical Lubrication Theory, we compare results from (1) the full Navier-Stokes equations, (2) a lubrication theory relative to the “natural,” i.e., bipolar, coordinate system of the geometry that neglects fluid inertia, and (3) the classical Reynolds Lubrication Theory that neglects both fluid inertia and film curvature. By applying parametric continuation techniques, we then estimate the Reynolds number range of validity of the laminar flow assumption of classical theory. The study demonstrates that both the Navier-Stokes and the “bipolar lubrication” solutions converge monotonically to results from classical Lubrication Theory, one from below and the other from above. Furthermore the oil-film force is shown to be invariant with Reynolds number in the range 0 < R < Rc for conventional journal bearing geometry, where Rc is the critical value of the Reynolds number at first bifurcation. A similar conclusion also holds for the off-diagonal components of the bearing stiffness matrix, while the diagonal components are linear in the Reynolds number, in accordance with the small perturbation theory of DiPrima and Stuart.

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Fetuga, Ibrahim Ademola, Olabode Thomas Olakoyejo, Antônio Marcos de Oliveira Siqueira, Joshua Kolawole Gbegudu, and Ebenezer Aderibigbe Adeyemi. "Thermal and Fluid Flow Performance Analysis of Tubular Microchannel Heat Sinks with Inward Protrusions and Nanofluids." Journal of Engineering and Exact Sciences 8, no. 5 (April 22, 2022): 14233–01. http://dx.doi.org/10.18540/jcecvl8iss5pp14233-01e.

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In this work, the application of protrusions and nanofluids to improve the performance of tubular-microchannel heat sink (MCHS) is proposed and investigated computationally. The three-dimensional Navier-Stokes and energy equations were solved numerically using the finite volume method incorporated into the ANSYS (Fluent) software package. The effects of different types of nanofluid (Al2O3, CuO, ZnO in pure water), the volume fraction of the nanoparticles (0% to 4%) and height of the protrusion ( 2um-6um) on microchannel heat sinks were investigated under the steady-state condition and Reynold numbers (400-2000) with constant heat flux of 9 x 106 W/m2. It was revealed that thermal performance improved as protrusion height increased. At Re=2 000 , for Al2O3 nanofluid (NAN) with a volume fraction ( of 4% and a protrusion height (H) of 2um to 6um yielded a thermal performance value of 1.59, 1.68, 1.77, 1.86, and 1.96 times that of MCHS without the protrusion, respectively. In addition, at a volume fraction of 4%, protrusion height of 6um and Reynolds number of 800, the Al2O3, CuO, and ZnO nanofluids yielded a thermal performance value of 1.79, 1.08, and 1.07 times that of pure water, respectively. Furthermore, at a Reynolds number of 400 and a volume fraction of 4%, the Al2O3–water nanofluid reduced the maximum temperature of the MCHS wall by 4% , whereas - and -nanofluids decreased the MCHS wall maximum temperature by 0.5% and 0.48% when compared to pure water, respectively. However, for all the cases of volume fraction (1% to 4%), there was an increase trend in the value of thermal performance for the Reynolds number range of 400 to 800 , and decrease with the Reynolds number range of 800 to 2 000.

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Einav, S., and M. Sokolov. "An Experimental Study of Pulsatile Pipe Flow in the Transition Range." Journal of Biomechanical Engineering 115, no. 4A (November 1, 1993): 404–11. http://dx.doi.org/10.1115/1.2895504.

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The study of pulsatile flows is relevant to many areas of applications. Typical applications include aerodynamics, biofluid mechanics, wind flows, and gas transport. Transition to turbulence during pulsatile flow is physiologically and clinically important. It has been suggested as a possible mechanism to enhance the transport of gases during high-frequency ventilation, may be related to valvular regurgitation and heart murmurs and to post stenotic dilatation and aneurysms. Measurements in a pulsatile pipe flow with a superimposed mean flow are reported. Data were taken in a water flow with mean Reynolds numbers in the range of 0 < Rem < 3000, oscillating Reynolds numbers of 0 < Reω < 4000, and Stokes parameter 7 < λ < 15. Velocity profiles of various phases of the flow, condition for flow reversal, and pressure losses were measured. The adequacy of a quasi-steady-state model is discussed. Condition for transition is determined by visually inspecting velocity signals at the centerline.

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Journal articles on the topic 'Reynolds Range'

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