Relevant bibliographies by topics / Reynolds Ranges

Academic literature on the topic 'Reynolds Ranges'

Author: Grafiati
Published: 10 December 2022
Last updated: 28 January 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Contents

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Reynolds Ranges.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Reynolds Ranges"

1

Huang, Xiao Qing, Xu Zhang, and Chun Guang Li. "Experimental Research on Resistance and Heat Transfer Properties of Corrugated Plate Air-Cooled Heat Exchanger." Advanced Materials Research 354-355 (October 2011): 153–58. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.153.

Full text
Abstract:
Experimental research on resistance and heat transfer properties of corrugated plate air-cooled heat exchanger under the condition of variable air and hot water flow rates has been conducted. The pressure drop and convection heat transfer coefficient correlation expressions both the air side and hot water side are acquired, where the Reynolds number for air side ranges from 401 to 6602 and the Reynolds number for water side ranges from 2536 to 19301 are adaptable.
APA, Harvard, Vancouver, ISO, and other styles
2

Elhadi Kh. Abugnah, Wan Saiful-Islam Wan Salim, Abdulhafid M. Elfaghi, and Zamani Ngali. "Comparison of 2D and 3D Modelling Applied to Single Phase Flow of Nanofluid through Corrugated Channels." CFD Letters 14, no. 1 (January 11, 2022): 128–39. http://dx.doi.org/10.37934/cfdl.14.1.128139.

Full text
Abstract:
Nanofluid flow through non-corrugated and corrugated channels is studied using a two-dimensional (2D) and three dimensions (3D) numerical simplification. Due to the high computational costs of a full 3D grid model, the 2D approach offer a more practical advantage. However, little information about its validity is available. The aim of this study is to explore to which extent 2D simulations can describe the flow within a 3D geometry, and to investigate how effective the commonly used 2D numerical simplification is in nanofluid flow through non-corrugated and corrugated channels. A case study has implemented with 2D and 3D mesh models to compare their results taking into consideration the analysis of heat transfer and pressure drop. A simulation has been carried out using Ansys fluent software to compare the results for different Reynolds Numbers ranges from 10000 to 30000 and different geometries non-corrugated, semicircle and rectangular channels. The results show that for non-corrugated channel there is a slight difference between 2D and 3D results for all Reynolds number ranges, while for both semicircle and rectangular corrugated channels, the difference becomes larger for high Reynold’s Number.
APA, Harvard, Vancouver, ISO, and other styles
3

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.

Full text
Abstract:
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.
APA, Harvard, Vancouver, ISO, and other styles
4

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.

Full text
Abstract:
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.
APA, Harvard, Vancouver, ISO, and other styles
5

Iwata, Naoyuki, Hiroki Suzuki, and Shinsuke Mochizuki. "Numerical simulation of viscosity/implicit large-eddy steady turbulence with the Reynolds number dependency." Journal of Physics: Conference Series 2047, no. 1 (October 1, 2021): 012007. http://dx.doi.org/10.1088/1742-6596/2047/1/012007.

Full text
Abstract:
Abstract This study presents a numerical analysis that models small scale turbulence using numerical viscosity or implicit large-eddy simulation (LES). The motivation for focusing on these models is that the sub-grid scale components of LES are assumed to have a sufficiently high Reynolds number turbulence. The Reynolds number dependence of steady isotropic turbulence is used to validate the present analysis. Here, this dependency ranges from low to high Reynolds numbers. The results of this analysis are validated by comparing them with those of direct numerical simulation. The donor cell method and quick method are used as schemes of the numerical viscosity. Analysis based on the numerical viscosity can give accurate turbulent kinetic energy values at high Reynolds numbers and implicit LES at low Reynolds numbers. However, these models did not accurately predict static pressure fluctuations. These results were discussed by visualizing the large-scale turbulent structures.
APA, Harvard, Vancouver, ISO, and other styles
6

Oo, Zaw Zaw, Muhammad Younis Yamin, Hua Zhang, Muhammad Zaka, and Bo Hu. "Study of Laminar Horseshoe Vortex Using Particle Image Velocimetry." Applied Mechanics and Materials 110-116 (October 2011): 3249–54. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.3249.

Full text
Abstract:
—This study investigates the upstream of the juncture flows generated by the circular cross section cylindrical body mounted on a flat plate using PIV (Particle Image Velocimetry) technique. The flow structure of laminar horseshoe vortex and a topological insight into the flow pattern of the vortex system were observed. Vortex structures for ReD(Diameter Reynolds number) 1600, 2000, 2400 and 3500 are predicted and discussed in detail. Experiments were conducted to investigate the structure of steady and periodic horseshoe vortex, the effect of Diameter Reynolds number, location of horseshoe vortex core and its variation with the change in Diameter Reynolds number and the location and nature of the saddle point located most upstream of the leading edge of the cylinder. The results revealed that (a) two different flow regimes were observed corresponding to four Reynolds number ranges; (b) the upstream vortex systems approach closer to the cylinder whereas the distance of saddle point located upstream of the leading edge of the cylinder moves away from the wall when the Reynolds number increases.
APA, Harvard, Vancouver, ISO, and other styles
7

Chen, Yi, Udaya Kahangamage, Quan Zhou, and Chun Wah Leung. "Can hydrogen enriched biogas be used as domestic fuel? - Part I – Thermal Characteristics of Blended Biogas/H2 Impinging Flames." HKIE Transactions 28, no. 2 (June 30, 2021): 60–67. http://dx.doi.org/10.33430/v28n2thie-2020-0040.

Full text
Abstract:
Biogas is a renewable energy source widely produced by breakdowns of organic matters in natural environment and industry. However, it is not yet an ideal replacement of fossil fuels because its high CO2 content would deteriorate its thermal performance. To upgrade biogas for possible domestic application, hydrogen enrichment is proposed by adding high-grade hydrogen (H2) to biogas in order to improve its flammability and heating value, and reduce pollutant emission. However, most previous studies on blended Biogas/H2 focus on analysing the effects of H2 fraction and nozzle-to-plate distance on the heat flux profile and flame temperature. No comprehensive study has ever demonstrated the influence of the Reynolds number and equivalence ratio under a wide operating range. In this study, a test rig was built to investigate the effects of the Reynolds number and equivalence ratio on heat flux and thermal efficiency of blended biogas/H2 impinging flame. The blended biogas/H2 consisted of 80% biogas and 20% H2 addition in volume. Biogas was artificially made by 60% CH4 and 40% CO2 (BG60). The Reynolds number ranges from 300 to 1500 and equivalence ratio ranges from 1 to 3. A comparative study was also conducted between pure biogas (BG60) and biogas with 20% H2 enrichment.
APA, Harvard, Vancouver, ISO, and other styles
8

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.

Full text
Abstract:
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.
APA, Harvard, Vancouver, ISO, and other styles
9

DONZIS, D. A., and K. R. SREENIVASAN. "The bottleneck effect and the Kolmogorov constant in isotropic turbulence." Journal of Fluid Mechanics 657 (June 10, 2010): 171–88. http://dx.doi.org/10.1017/s0022112010001400.

Full text
Abstract:
A large database from direct numerical simulations of isotropic turbulence, including recent simulations for box sizes up to 40963 and the Taylor–Reynolds number Rλ ≈ 1000, is used to investigate the bottleneck effect in the three-dimensional energy spectrum and second-order structure functions, and to determine the Kolmogorov constant, CK. The difficulties in estimating CK at any finite Reynolds number, introduced by intermittency and the bottleneck, are assessed. The data conclusively show that the bottleneck effect decreases with the Reynolds number. On this basis, an alternative to the usual procedure for determining CK is suggested; this proposal does not depend on the particular choices of fitting ranges or power-law behaviour in the inertial range. Within the resolution of the numerical data, CK thus determined is a Reynolds-number-independent constant of ≈1.58 in the three-dimensional spectrum. A simple model including non-local transfer is proposed to reproduce the observed scaling features of the bottleneck.
APA, Harvard, Vancouver, ISO, and other styles
10

Luan, Yi Gang, and Hai Ou Sun. "Simplification Model for Prediction of Pressure Drop in Wire Mesh Mist Eliminator by CFD." Applied Mechanics and Materials 26-28 (June 2010): 297–302. http://dx.doi.org/10.4028/www.scientific.net/amm.26-28.297.

Full text
Abstract:
In this article, computational fluid dynamics(CFD) method is used to predict the pressure drop of a wire mesh mist eliminator. A simplification method is used during the simulation process to solve the difficulty of model building during the simulation of the mist pad. A two-dimensional model is employed to acquire the resistance of mesh pad with different layer spacing. The flow field is calculated using 2D Reynolds-averaged Navier-Stokes equations. turbulence model is used to simulate the Reynold stress. And pressure drop of wire mesh mist eliminator is expressed as a function of broad ranges of inlet velocity. After CFD simulation, model experiment study is carried on using a small scale wind-tunnel. The pressure drop is gained to testify the numerical simulation result.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Reynolds Ranges"

1

Symes, Joseph Alexander. "Dry inclined galloping of smooth circular cables in the critical reynolds number range." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546204.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Srinivasa, Murthy P. "Low Reynolds Number Airfoil Aerodynamics." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/229.

Full text
Abstract:
In this thesis we describe the development of Reynolds- averaged Navier Stokes code for the flow past two- dimensional configuration. Particularly, emphasis has been laid on the study of low Reynolds number airfoil aerodynamics. The thesis consists of five chapters covering the back ground history, problem formulation, method of solution and discussion of the results and conclusion. Chapter I deals with a detailed background history of low Reynolds number aerodynamics, problem associated with it, state of the art, its importance in practical applications in aircraft industries. Chapter II describes the mathematical model of the flow physics and various levels of approximations. Also it gives an account of complexity of the equations at low Reynolds number regarding flow separation, transition and reattachment. Chapter III describes method of solution, numerical algorithm developed, description of various upwind schemes, grid system, finite volume discrieti-zation of the governing equations described in Chapter II. Chapter IV describes the application of the newly developed Navier Stokes code for the test cases from GAMM Workshop proceedings. Also it describes validation of the code for Euler solutions, Blasius solution for the flow past flat plate and compressible Navier Stokes solution for the flow past NACA 0012 Airfoil at low Reynolds number. Chapter V describes the application of the Navier Stokes code for the more test cases of current practical interest . In this chapter laminar separation bubble characteristics are investigated in detail regarding formation, growth and shedding in an unsteady environment. Finally the conclusion is drawn regarding the robustness of the newly developed code in predicting the airfoil aerodynamic characteristics at low Reynolds number both in steady and unsteady environment. Lastly, suggestion for future work has been highlighted.
APA, Harvard, Vancouver, ISO, and other styles
3

Sutkowy, Mark Louis Jr. "Relationship between Rotor Wake Structures and Performance Characteristics over a Range of Low-Reynolds Number Conditions." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534768619864476.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Frazza, Loïc. "3D anisotropic mesh adaptation for Reynolds Averaged Navier-Stokes simulations." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS423.

Full text
Abstract:
Nous montrons dans cette thèse la capacité des schémas numériques modernes à simuler des écoulements turbulents sur des maillages totalement non-structurés générés automatiquement à l’aide de méthodes adaptatives. Nous détaillons le développement de différentes versions du modèle de Spalart-Allmaras ainsi que les choix numériques garantissant une robustesse suffisante du solver pour ne pas nécessiter de couche limite structurée. Nous introduisons en suite l’analyse d’erreur nécessaire pour proposer different estimateurs d’erreur à la base de l’optimisation de maillage. Cette méthodologie est testée sur différents cas tests d’aérodynamique externe et de turbomachines et comparée aux méthodes traditionnelles de géneration de maillage. Nous montrons ainsi la capacité des méthodes d’adaptation de maillage à générer automatiquement des maillages adaptés optimaux pour les simulations RANS autour de géométries réalistes et complexes
The fast and reliable simulation of turbulent flow using Reynolds Averaged Navier Stokes (RANS) models is a major financial issue for many industries. With the increasing complexity of geometries and simulated flows, as well as requirements in terms of fidelity, the generation of appropriate meshes has become a key link in the chain of computation. We show in this thesis the ability of modern numerical schemes to simulate turbulent flows on fully unstructured meshes generated automatically using mesh adaptation methods. We present the implementation of different versions of the Spalart-Allmaras model as well as the numerical choices guaranteeing a sufficient robustness of the solver in order to not require a structured boundary layer. We then introduce the error analysis necessary to propose different error estimators for mesh optimization. This methodology is tested on various external aerodynamic and turbomachinery test cases and compared to traditional mesh generation methods. We show the ability of mesh adaptation methods to automatically generate optimal mesh sizes for RANS simulations on realistic and complex geometries
APA, Harvard, Vancouver, ISO, and other styles
5

Bouratsis, Polydefkis. "Scour at the Base of Hydraulic Structures: Monitoring Instrumentation and Physical Investigations Over a Wide Range of Reynolds Numbers." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/71880.

Full text
Abstract:
Hydraulically induced scour of the streambed at the base of bridge piers is the leading cause of bridge failures. Despite the significant scientific efforts towards the solution of this challenging engineering problem, there are still no reliable tools for the prediction and mitigation of bridge scour. This shortcoming is attributed to the lack of understanding of the physics behind this phenomenon. The experimental studies that attempted the physical investigation of bridge scour in the past have faced two main limitations: i) The characterization of the dynamic interaction between the flow and the evolving bed that is known to drive scour, was not possible due to the limitations in the available instrumentation and the significant experimental difficulties; ii) Most of the existing literature studies are based on the findings of laboratory experiments whose scale is orders of magnitudes smaller compared to bridges in the field, while the scale effects on the scour depth have never been quantified. The objective of this research was to enhance the existing understanding of the phenomenon by tackling the aforementioned experimental challenges. To accomplish this, the first part of this work involved the development of a new underwater photogrammetric technique for the monitoring of evolving sediment beds. This technique is able to obtain very high resolution measurements of evolving beds, thus allowing the characterization of their dynamic properties (i.e. evolving topography and scour rates) and overcoming existing experimental limitations. Secondly, the underwater photogrammetric technique was applied on a bridge scour experiment, of simple geometry, and the dynamic morphological characteristics of the phenomenon were measured. The detailed measurements along with reasonable comparisons with descriptions of the flow, from past studies, were used to provide insight on the interaction between the flow and the bed and describe quantitatively the mechanisms of scour. Finally, the scale effects on scour were studied via the performance of two experiments under near-prototype conditions. In these experiments the effects of the Reynolds number on the flow and the scour were quantified and implications concerning existing small-scale studies were discussed.
Ph. D.
APA, Harvard, Vancouver, ISO, and other styles
6

Shin, Sangmook. "Reynolds-Averaged Navier-Stokes Computation of Tip Clearance Flow in a Compressor Cascade Using an Unstructured Grid." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/28947.

Full text
Abstract:
A three-dimensional unstructured incompressible RANS code has been developed using artificial compressibility and Spalart-Allmaras eddy viscosity model. A node-based finite volume method is used in which all flow variables are defined at the vertices of tetrahedrons in an unstructured grid. The inviscid fluxes are computed by using the Roe's flux difference splitting method, and higher order accuracy is attained by data reconstruction based on Taylor series expansion. Gauss theorem is used to formulate necessary gradients. For time integration, an implicit scheme based on linearized Euler backward method is used. A tetrahedral unstructured grid generation code has been also developed and applied to the tip clearance flow in a highly staggered cascade. Surface grids are first generated in the flow passage and blade tip by using several triangulation methods including Delaunay triangulation, advancing front method and advancing layer method. Then the whole computational domain including tip gap region is filled with prisms using the surface grids. Each prism is divided into three tetrahedrons. To accomplish this division in a consistent manner, connectivity pattern is assigned to each triangle in the surface grids. A new algorithm is devised to assign the connectivity pattern without reference to the particular method of triangulation. This technique offers great flexibility in surface grid generation. The code has been validated by comparisons with available computational and experimental results for several test cases: invisicd flow around NACA section, laminar and turbulent flow over a flat plate, turbulent flow through double-circular arc cascade and laminar flow through a square duct with 90° bend. For the laminar flat plate case, the velocity profile and skin friction coefficient are in excellent agreement with Blasius solution. For the turbulent flat plate case, velocity profiles are in full agreement with the law of the wall up to Reynolds number of 1.0E8, however, the skin friction coefficient is under-predicted by about 10% in comparison with empirical formula. Blade loading for the two-dimensional circular arc cascade is also compared with experiments. The results obtained with the experimental inflow angle (51.5° ) show some discrepancies at the trailing edge and severely under-predict the suction peak at the leading edge. These discrepancies are completely remedied if the inflow angle is increased to 53.5° . The code is also capable of predicting the secondary flow in the square duct with 90° bend, and the velocity profiles are in good agreement with measurements and published Navier-Stokes computations. Finally the code is applied to a linear cascade that has GE rotor B section with tip clearance and a high stagger angle of 56.9° . The overall structure of the tip clearance flow is well predicted. Loss of loading due to tip leakage flow and reloading due to tip leakage vortex are presented. On the end wall, separation line of the tip leakage vortex and reattachment line of passage vortex are identified. The location of the tip leakage vortex in the passage agrees very well with oil flow visualization. Separation bubble on the blade tip is also predicted. Mean streamwise velocity contours and cross sectional velocity vectors are compared with experimental results in the near wake, and good agreements are observed. It is concluded that Spalart-Allmaras turbulence model is adequate for this type of flow field except at locations where the tip leakage vortex of one blade interacts with the wake of a following blade. This situation may prevail for blades with longer span and/or in the far wake. Prediction of such an interaction presents a challenge to RANS computations. The effects of blade span on the flow structure have been also investigated. Two cascades with blades of aspect ratios of 0.5 and 1.0 are considered. By comparing pressure distributions on the blade, it is shown that the aspect ratio has strong effects on loading distribution on the blade although the tip gap height is very small (0.016 chord). Grid convergence study has been carried out with three different grids for pressure distributions and limiting streamlines on the end wall.
Ph. D.
APA, Harvard, Vancouver, ISO, and other styles
7

Renard, Nicolas. "Simulations numériques avancées et analyses physiques de couches limites turbulentes à grand nombre de Reynolds." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066041/document.

Full text
Abstract:
Mieux comprendre les spécificités de la dynamique des couches limites à grand nombre de Reynolds malgré les contraintes métrologiques et son coût de simulation numérique est crucial. A titre d'exemple, cette dynamique peut déterminer plus de la moitié de la traînée d'un avion en croisière. Décrire la turbulence pariétale peut guider la résolution numérique d'une partie des fluctuations à un coût maîtrisé par des stratégies WMLES (simulation des grandes échelles avec modèle de paroi). Les présentes analyses physiques de couches limites turbulentes incompressibles à gradient de pression nul et à grand nombre de Reynolds s'appuient sur des simulations numériques avancées. Après validation d'une base de données, le frottement moyen pariétal est décomposé selon l'identité FIK (Fukagata et al. (2002)), dont l'application malgré le développement spatial est discutée. Une analyse spectrale montre que les grandes échelles (\lambda_x > \delta) contribuent à environ la moitié du frottement vers Re_\theta = 10^4. Les limitations de l'identité FIK motivent la dérivation d'une décomposition physique de la génération du frottement dont le comportement asymptotique est alors relié à la production d'énergie cinétique turbulente dans la zone logarithmique. Pour mieux reconstruire les spectres spatiaux, une nouvelle méthode d'estimation de la vitesse de convection turbulente en fonction de la longueur d'onde des fluctuations, adaptée au développement spatial et à des signaux temporels de durée finie, est dérivée, interprétée et évaluée à Re_\theta = 13000. Certaines des conclusions éclairent des modifications d'une stratégie WMLES, le mode III de la méthode ZDES
Better understanding the specificities of the dynamics of high-Reynolds number boundary layers despite metrological constraints and its numerical simulation cost is crucial. For instance, this dynamics can determine more than half of the drag of a cruising aircraft. Describing wall turbulence can guide the numerical resolution of some of the fluctuations at a limited cost by WMLES strategies (wall-modelled large eddy simulation). The present physical analyses of zero-pressure gradient incompressible turbulent boundary layers at high Reynolds number rely on advanced numerical simulations. After validating a database, mean skin friction is decomposed by means of the FIK identity (Fukagata et al. (2002)), whose application despite the spatial growth is discussed. A spectral analysis shows that the large scales (\lambda_x > \delta) contribute approximately half of the friction near Re_\theta = 10^4. The limitations of the FIK identity motivate the derivation of a physical decomposition of the generation of friction whose asymptotic behaviour is then related to turbulent kinetic energy production in the logarithmic layer. In order to better reconstruct spatial spectra, a new method to estimate the turbulent convection velocity as a function of the wavelength of the fluctuations, adapted to spatial growth and to temporal signals of finite duration, is derived, interpreted, and assessed at Re_\theta = 13000. Some of the conclusions enlighten modifications to a WMLES strategy, mode III of the ZDES method
APA, Harvard, Vancouver, ISO, and other styles
8

Li, Zhiyong. "Data-Driven Adaptive Reynolds-Averaged Navier-Stokes k - ω Models for Turbulent Flow-Field Simulations." UKnowledge, 2017. http://uknowledge.uky.edu/me_etds/93.

Full text
Abstract:
The data-driven adaptive algorithms are explored as a means of increasing the accuracy of Reynolds-averaged turbulence models. This dissertation presents two new data-driven adaptive computational models for simulating turbulent flow, where partial-but-incomplete measurement data is available. These models automatically adjust (i.e., adapts) the closure coefficients of the Reynolds-averaged Navier-Stokes (RANS) k-ω turbulence equations to improve agreement between the simulated flow and a set of prescribed measurement data. The first approach is the data-driven adaptive RANS k-ω (D-DARK) model. It is validated with three canonical flow geometries: pipe flow, the backward-facing step, and flow around an airfoil. For all 3 test cases, the D-DARK model improves agreement with experimental data in comparison to the results from a non-adaptive RANS k-ω model that uses standard values of the closure coefficients. The second approach is the Retrospective Cost Adaptation (RCA) k-ω model. The key enabling technology is that of retrospective cost adaptation, which was developed for real-time adaptive control technology, but is used in this work for data-driven model adaptation. The algorithm conducts an optimization, which seeks to minimize the surrogate performance, and by extension the real flow-field error. The advantage of the RCA approach over the D-DARK approach is that it is capable of adapting to unsteady measurements. The RCA-RANS k-ω model is verified with a statistically steady test case (pipe flow) as well as two unsteady test cases: vortex shedding from a surface-mounted cube and flow around a square cylinder. The RCA-RANS k-ω model effectively adapts to both averaged steady and unsteady measurement data.
APA, Harvard, Vancouver, ISO, and other styles
9

Benarafa, Younes. "Application du couplage RANS / LES aux écoulements turbulents à haut nombre de Reynolds de l'industrie nucléaire." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2005. http://tel.archives-ouvertes.fr/tel-00011371.

Full text
Abstract:
La difficulté principale de réaliser la simulation numérique d'un écoulement turbulent à haut nombre de Reynolds est de préserver la capture des effets instationnaires sans induire un coût de calcul prohibitif. Nous avons, tout d'abord, exhibé les principaux défauts des simulations des grandes échelles avec un modèle de paroi standard dans une configuration de canal plan bi-périodique dans un contexte de maillage grossier. Dans ce cadre, nous avons proposé deux approches basées sur une stratégie de couplage RANS/LES pour corriger pour corriger ces défauts. La première repose sur l'application du modèle de paroi TBLE à une simulations des grandes échelles, qui consiste à résoudre des équations de couche limite simplifiées et instationnaires avec une modélisation de type RANS dans la zone proche paroi. La seconde consiste à réaliser simultanément un calcul RANS et une simulation des grandes échelles dont le champ filtré moyen sera corrigé grâce au calcul RANS par l'intermédiaire d'un terme de forçage. Ces différentes méthodes de modélisations ont été implémentéesdanns le code de calcul TRIO_U du CEA Grenoble. Les configurations étudiées sont le canal plan bi-périodique et un écoulement pariétal dans une matrice d'obstacles cubiques. Les deux approches fournissent des résultats encourageants et permettent d'effectuer des simulations instationnaires à un coût numérique réduit.
APA, Harvard, Vancouver, ISO, and other styles
10

Tobias, Brännvall. "Source Term Estimation in the Atmospheric Boundary Layer : Using the adjoint of the Reynolds Averaged Scalar Transport equation." Thesis, Umeå universitet, Institutionen för fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-103671.

Full text
Abstract:
This work evaluates whether the branch of Reynolds Averaging in Computational Fluid Dynamics can be used to, based on real field measurements, find the source of the measured gas in question. The method to do this is via the adjoint to the Reynolds Averaged Scalar Transport equation, explained and derived herein. Since the Inverse is only as good as the main equation, forward runs are made to evaluate the turbulence model. Reynolds Averaged Navier Stokes is solved in a domain containing 4 cubes in a 2x2 grid, generating a velocity field for said domain. The turbulence model in question is a union of two modifications to the standard two equation k-ε model in order to capture blunt body turbulence but also to model the atmospheric boundary layer. This field is then inserted into the Reynolds Averaged Scalar Transport equation and the simulation is compared to data from the Environmental Flow wind tunnel in Surrey. Finally the adjoint scalar transport is solved, both for synthetic data that was generated in the forward run, but also for the data from EnFlo. It was discovered that the turbulent Schmidt number plays a major role in capturing the dispersed gas, three different Schmidt numbers were tested, the standard 0.7, the unconventional 0.3 and a height dependent Schmidt number. The widely accepted value of 0.7 did not capture the dispersion at all and gave a huge model error. As such the adjoint scalar transport was solved for 0.3 and a height dependent Schmidt number. The interaction between measurements, the real source strength (which is not used in the adjoint equation, but needed to find the source) and the location of the source is intricate indeed. Over estimation and under estimation of the forward model may cancel out in order to find the correct source, with the correct strength. It is found that Reynolds Averaged Computational fluid dynamics may prove useful in source term estimation.
Detta arbete utvärderar hurvida Reynolds medelvärdesmodellering inom flödessimuleringar kan användas till att finna källan till en viss gas baserat på verkliga mätningar ute i fält. Metoden går ut på att använda den adjungerade ekvationen till Reynolds tidsmedlade skalära transportekvationen, beskriven och härledd häri. Då bakåtmodellen bygger på framåtmodellen, måste såleds framåtmodellen utvärderas först. Navier-Stokes ekvationer med en turbulensmodell löses i en domän, innehållandes 4 kuber i en 2x2 orientering, för vilken en hastighetsprofil erhålles. Turbulensmodellen som användes är en union av två olika k-ε modeller, där den ena fångar turbulens runt tröga objekt och den andra som modellerar atmosfäriska gränsskiktet. Detta fält används sedan i framåtmodellen av skalära transportekvationen, som sedan jämförs med körningar från EnFlo windtunneln i Surrey. Slutligen testkörs även den adjungerade ekvationen, både för syntetiskt data genererat i framåtkörningen men även för data från EnFlo tunneln. Då det visade sig att det turbulenta Schmidttalet spelar stor roll inom spridning i det atmosfäriska gränsskiktet, gjordes testkörningar med tre olika Schmidttal, det normala 0.7, det väldigt låga talet 0.3 samt ett höjdberoende Schmidttal. Det visade sig att det vanligtvis använda talet 0.7 inte alls lyckas fånga spridningen tillfredställande och gav ett stort modellfel. Därför löstes den adjungerade ekvationen för 0.3 samt för ett höjdberoende Schmidttal. Interaktionen mellan mätningar, den riktiga källstyrkan (som är okänd i den adjungerade ekvationen) samt källpositionen är onekligen intrikat. Över- samt underestimationer av framåtmodellen kan ta ut varandra i bakåtmodellen för att finna rätt källa, med rätt källstyrka. Det ter sig som Reynolds turbulensmodellering mycket möjligt kan användas inom källtermsuppskattning.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Reynolds Ranges"

1

Parsons, Chuck. Texas Ranger N.O. Reynolds, the intrepid. Honolulu, HI: Talei Publishers, 2005.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
2

author, Brice Donaly E., ed. Texas Ranger N.O. Reynolds, the Intrepid. Denton, Texas: University of North Texas Press, 2014.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
3

Pfenninger, Werner. Optimization of natural laminar flow airfoils for high section lift-to-drag ratios in the lower Reynolds number range. Washington, D. C: AIAA, 1989.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
4

Experimental surface pressure data obtained on 65 ̊delta wing across Reynolds number and Mach number ranges. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1996.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
5

United States. National Aeronautics and Space Administration., ed. EXPERIMENTAL SURFACE PRESSURE DATA OBTAINED ON 65 DEG DELTA WING ACROSS REYNOLDS NUMBER AND MACH NUMBER RANGES... NASA-TM-4645-VOL-2 ... MAR. [S.l: s.n., 1998.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
6

J, Boyle R., and Lewis Research Center, eds. Aerodynamics of a transitioning turbine stator over a range of Reynolds numbers. [Cleveland, Ohio]: National Aeronautics and Space Administration, Lewis Research Center, 1998.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
7

D, Moore Royce, United States. Army Aviation Research and Technology Activity., and United States. National Aeronautics and Space Administration., eds. Performance of two 10-lb/sec centrifugal compressors with different blade and shroud thicknesses operating over a range of Reynolds numbers. [Washington, DC]: National Aeronautics and Space Administration, 1987.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
8

D, Moore Royce, United States. Army Aviation Research and Technology Activity., and United States. National Aeronautics and Space Administration., eds. Performance of two 10-lb/sec centrifugal compressors with different blade and shroud thicknesses operating over a range of Reynolds numbers. [Washington, DC]: National Aeronautics and Space Administration, 1987.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
9

Performance of two 10-lb/sec centrifugal compressors with different blade and shroud thicknesses operating over a range of Reynolds numbers. [Washington, DC]: National Aeronautics and Space Administration, 1987.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
10

Escudier, Marcel. Turbulent flow. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198719878.003.0018.

Full text
Abstract:
In this chapter the principal characteristics of a turbulent flow are outlined and the way that Reynolds’ time-averaging procedure, applied to the Navier-Stokes equations, leads to a set of equations (RANS) similar to those governing laminar flow but including additional terms which arise from correlations between fluctuating velocity components and velocity-pressure correlations. The complex nature of turbulent motion has led to an empirical methodology based upon the RANS and turbulence-transport equations in which the correlations are modelled. An important aspect of turbulent flows is the wide range of scales involved. It is also shown that treating near-wall turbulent shear flow as a Couette flow leads to the Law of the Wall and the log law. The effect of surface roughness on both the velocity distribution and surface shear stress is discussed. It is shown that the distribution of mean velocity within a turbulent boundary layer can be represented by a linear combination of the near-wall log law and an outer-layer Law of the Wake.
APA, Harvard, Vancouver, ISO, and other styles

Book chapters on the topic "Reynolds Ranges"

1

Bragg, Don C., and Michael G. Shelton. "The Value of Old Forests: Lessons from the Reynolds Research Natural Area." In USDA Forest Service Experimental Forests and Ranges, 61–84. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4614-1818-4_3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Ishida, Takahiro, Takahiro Tsukahara, and Yasuo Kawaguchi. "DNS of Rotating Turbulent Plane Poiseuille Flow in Low Reynolds- and Rotation-Number Ranges." In Progress in Turbulence V, 177–82. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-01860-7_28.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Deville, Michel O. "Turbulence." In An Introduction to the Mechanics of Incompressible Fluids, 211–56. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-04683-4_9.

Full text
Abstract:
AbstractThe Reynolds decomposition and statistical averaging of velocity and pressure generate the Reynolds averaged Navier–Stokes (RANS) equations. The closure problem is solved by the introduction of a turbulence constitutive equation. Several linear turbulence models are presented in the RANS framework: $$K-\varepsilon , K-\omega $$ K - ε , K - ω . The solution of the RANS equations for the turbulent channel flow is elaborated giving the celebrated logarithmic profile. Non-linear models are built on the anisotropy tensor and the incorporation of the concept of integrity bases. The chapter ends with the theory of large eddy simulations with a few up-to-date models: dynamic model, approximate deconvolution method.
APA, Harvard, Vancouver, ISO, and other styles
4

Stoellinger, Michael, Stefan Heinz, and Pankaj Saha. "Reynolds Stress Closure in Hybrid RANS-LES Methods." In Progress in Hybrid RANS-LES Modelling, 319–28. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15141-0_26.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Yakhot, V., C. Bartlett, H. Chen, R. Shock, I. Staroselsky, and J. Wanderer. "Universal Reynolds Number of Transition and Derivation of Turbulent Models." In Progress in Hybrid RANS-LES Modelling, 37–55. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15141-0_3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Danjkov, B. N., E. S. Kornienko, and V. V. Kudrjavtsev. "Supersonic Separation Zone Pressure Fluctuations for Wide Range of Reynolds Number." In Separated Flows and Jets, 237–43. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-84447-8_34.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Maduta, R., and S. Jakirlic. "An Eddy-Resolving Reynolds Stress Transport Model for Unsteady Flow Computations." In Progress in Hybrid RANS-LES Modelling, 77–89. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-31818-4_6.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Wang, Rui, and Zuoli Xiao. "Reynolds-Constrained Large-Eddy Simulation: Sensitivity to Constraint and SGS Models." In Progress in Hybrid RANS-LES Modelling, 131–42. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-27607-2_10.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Itam, Emmanuelle, Stephen Wornom, Bruno Koobus, and Alain Dervieux. "Hybrid Simulation of High-Reynolds Number Flows Relying on a Variational Multiscale Model." In Progress in Hybrid RANS-LES Modelling, 207–17. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-70031-1_17.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Fujii, Kozo. "Role of RANS, Hybrid and LES for Wing Flow Simulations at Relatively Low Reynolds Numbers." In Progress in Hybrid RANS-LES Modelling, 45–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-31818-4_4.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Reynolds Ranges"

1

Huang, LiDong, and Kevin J. Farrell. "Mixed Convection in Vertical Tubes: High Reynolds Number." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-23266.

Full text
Abstract:
The complex interaction of forced and natural convection depends on flow regime and flow direction. Aiding flow occurs when both driving forces act in the same direction (heating upflow fluid and cooling downflow fluid); opposing flow occurs when they act in different directions (cooling upflow fluid and heating downflow fluid). This paper discusses the buoyancy effect on forced convection for single-phase flows in vertical tubes. To evaluate mixed convection methods, Heat Transfer Research, Inc. (HTRI) recently collected water and propylene glycol data in two vertical tubes of different tube diameters. The data cover wide ranges of Reynolds, Grashof, and Prandtl numbers and differing ratios of heated tube length to diameter in laminar, transition, and turbulent forced flow regimes. In this paper, we focus on mixed convection with Reynolds numbers higher than 2000. Using HTRI data and experimental data in literature, we demonstrate that natural convection can greatly increase or decrease the convective heat transfer coefficient. In addition, we establish that natural convection should not be neglected if the Richardson number is higher than 0.01 or the mixed turbulent parameter Ra1/3/(Re0.8 Pr0.4) is higher than 0.05 even in forced turbulent flow with Reynolds numbers greater than 10000. High resolution Reynolds-Averaged Navier-Stokes (RANS) simulations of several experimental conditions confirm the importance of the buoyancy effect on the production of turbulence kinetic energy. We also determine that flow regime maps are required to predict the mixed convection heat transfer coefficient accurately.
APA, Harvard, Vancouver, ISO, and other styles
2

Lázaro, Benigno J., Ezequiel González, David Cadrecha, Antonio Antoranz, and Jorge Parra. "Low Reynolds Number Response of High Efficiency, Intermediate Pressure Compressor Profiles." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63283.

Full text
Abstract:
Current trends on intermediate pressure, axial compressors designs for aeroengine applications demand to extend their operation envelope into low Reynolds number regimes, of the order of 105 based on the real chord and inlet velocity (Re). In this range, a very limited open experimental database on profile performance can be found. Furthermore, in order to propose high efficiency designs for this regime, it is critical to determine and to understand the profile behaviour with respect to different operating parameters. In this work, a detailed experimental study of a proposed high efficiency, intermediate pressure compressor aerofoil has been carried out, both for design and off-design flow incidences, in the range 1.5 · 105 < Re < 3.5 · 105,. The experimental facility is a low-speed linear cascade where different boundary suction strategies have been implemented to optimize the flow periodicity and to minimize pressure gradient perturbations induced by end-wall secondary flow development, in an effort to ensure high quality, 2D passage flow evolution both at design and significant off-design incidences. High resolution total pressure loss and LDV traverses performed at different streamwise locations have been carried out to describe the flow evolution. The characterizations performed at close to nominal incidence give a profile loss dependence on the Reynolds number that exhibits two clearly differentiated ranges, with the lower one exhibiting a higher profile loss dependence on the Reynolds number. At large off-design incidences, the profile loss coefficient practically becomes independent of the Reynolds number, rapidly increasing as the incidence is increased. In both cases physical arguments and scaling laws based on the experimental evidence are proposed to explain the profile behavior. RANS and URANS based CDF simulations have been also conducted, showing their ability and limitations to capture the experimentally observed aerofoil behavior.
APA, Harvard, Vancouver, ISO, and other styles
3

Rallabandi, Akhilesh P., Nawaf Alkhamis, and Je-Chin Han. "Heat Transfer and Pressure Drop Measurements for a Square Channel With 45Deg Round Edged Ribs at High Reynolds Numbers." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59546.

Full text
Abstract:
Experiments to determine heat transfer coefficients and friction factors are conducted on a stationary 45 deg parallel rib roughened square channel which simulates a turbine blade internal coolant passage. Copper plates fitted with silicone heaters and thermocouples are used to measure regionally averaged heat transfer coefficients. Reynolds numbers studied range from 30,000 to 400,000. The ribs studied have rounded (filleted) edges to account for manufacturing limitations of actual engine blades. The rib height (e) to hydraulic diameter (D) ratio (e/D) ranges from 0.1 to 0.2; spacing (p) to height ratio (p/e) ranges from 5 to 10. Results indicate an increase in heat transfer due to ribs at the cost of a higher friction factor, especially at higher Reynolds Numbers. Round edged ribs experience a similar heat transfer coefficient and a lower friction factor compared to sharp edged ribs, especially at higher values of rib height. Correlations predicting Nu and f as a function of e/D, p/e and Re are presented. Also presented are correlations for heat transfer and friction roughness parameters (G and R).
APA, Harvard, Vancouver, ISO, and other styles
4

Poirel, Dominique, Yael Harris, and Aze´mi Benaissa. "Aeroelastic Dynamics of a NACA 0012 Airfoil in the Transitional Reynolds Number Regime." In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93957.

Full text
Abstract:
The work discussed herein is a focused extension of a series of studies that were carried out at the Aeroelasticity Laboratory of the Royal Military College of Canada in recent years. Initial work revealed the presence of self-excited oscillations over certain ranges of airspeed when a NACA 0012 airfoil was immersed in the laboratory’s wind tunnel and allowed to oscillate freely in both pitch and heave. The range of airspeeds tested corresponded to Reynolds numbers in the low-to-moderate regime. While the aeroelastic apparatus is capable of two-degrees-of-freedom motion, the present work concerns only the motion of the airfoil when it is constrained to rotate in pure pitch. A parametric investigation is presently being undertaken to more fully comprehend the airfoil’s pitch behaviour, specifically the amplitude and frequency of its oscillations which are observed in the following range of chord based Reynolds numbers: 5.0 × 104 ≤ Rec ≤ 1.2 × 105. This paper focuses on the effect of the stiffness of the springs used in the apparatus. Other parameters such as surface roughness, turbulence intensity, temperature and initial conditions are also briefly discussed. In conjunction with the pitch oscillation measurements, preliminary results reveal vortices to be present in the wake. In an attempt to determine the frequency and character of these flow structures, as well as to understand the relationship between the airfoil motion and wake dynamics, hot-wire anemometry measurements have been performed.
APA, Harvard, Vancouver, ISO, and other styles
5

Lie, Halvor, Henning Braaten, Jamison Szwalek, Massimiliano Russo, and Rolf Baarholm. "Drilling Riser VIV Tests With Prototype Reynolds Numbers." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11643.

Full text
Abstract:
For deep-water riser systems, Vortex Induced Vibrations (VIV) may cause significant fatigue damage. It appears that the knowledge gap of this phenomenon is considerable and this has caused a high level of research activity over the last decades. Small scale model tests are often used to investigate VIV behaviour. However, one substantial uncertainty in applying such results is scaling effects, i.e. differences in VIV response in full scale flow and small scale flow. To (partly) overcome this obstacle, a new innovative VIV test rig was designed and built at MARINTEK to test a rigid full scale riser model. The rigid riser model is mounted vertically and can either be elastically mounted or be given a forced motion. In the present version, the cylinder can only move in the cross-flow (CF) direction and is restricted in the in-line (IL) direction. The paper reports results from a drilling riser VIV experiment where the new rest rig has been used. The overall objective of the work is to study possible VIV suppression to improve operability of retrievable riser systems with auxiliary lines by adding riser fins. These fins are normally used as devices for protection of the auxiliary lines. The test program has recently been completed and analysis is an on-going activity. However, some results can be reported at this stage and more results are planned to be published. A bare riser model was used in a Reynolds number (Rn) scaling effect study. The riser model was elastically mounted and towed over a reduced velocity range around 4 – 10 in two different Rn ranges, 75 000 – 192 000 (subcritical regime) and 347 000 – 553 000 (critical regime). The difference in the displacement amplitude to diameter ratio, A/D, is found to be significant. The elastically mounted riser was also towed with various drilling riser configurations in order to study VIV/galloping responses. One configuration included a slick joint riser model with 6 kill & choke lines; another has added riser fins too. The riser model is based on a specific drilling riser and the kill and choke lines have various diameters and have a non-symmetrical layout. The various riser configurations have also been used in forced motion tests where the towed model has been given a sinusoidal CF motion. Forces have been measured. Determination of the force coefficients is still in progress and is planned to be reported later. Scaling effects appear to be a significant uncertainty and further research on the subject is recommended. The slick joint drilling riser configuration generally increased the displacements compared to displacements of the bare riser model. The drilling riser configuration with protection fins, kill and choke lines generally reduced the displacements compared to displacements of the bare riser model. For both riser systems, tests showed that the response is sensitive to the heading of the current.
APA, Harvard, Vancouver, ISO, and other styles
6

Kiser, Chris C., Tim A. Handy, Evan C. Lemley, Dimitrios V. Papavassiliou, and Henry J. Neeman. "Reynolds Number Dependence for Laminar Flow Loss Coefficients in Tee and Wye Junctions." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-31026.

Full text
Abstract:
In fluid flow piping systems, tee and wye junctions are commonly encountered and the study of flow through them has been well documented. Most of these studies have focused on flow characterized as turbulent for which there are nearly constant losses in pressure and kinetic energy in the junctions. Laminar flow has received much less attention since it is not frequently observed in macro scale piping systems where pipe diameters are measured in centimeters. The recent increase in use of micro scale flow devices calls for more research into laminar flow behavior that dictates the design and operation of these devices. This paper documents results from computational fluid dynamics (CFD) simulations of flow in planar tee and wye junctions. The junctions studied consisted of circular pipes with two outlets and one inlet. The angles between the tee and wye junctions were fixed to 180 and 60 degrees, respectively. The inlet pipe diameter was fixed at 50 microns and the outlet pipe diameters were chosen to satisfy the continuity equation constrained to have equal velocities in all pipes. The lengths of the inlet and outlet pipes were varied to achieve fully developed flow within the junction. Following a grid resolution study performed on a sample tee junction, a generalized algorithm was designed and implemented to create three-dimensional models of these junctions subject to the former conditions. In the CFD simulations, Reynolds number was varied in the laminar characterized region between 1 and 2000. The simulations calculated static pressure and velocity magnitude values for a number of planes intersecting the junctions along the inlet and outlet pipes. From these values, pressure and kinetic energy gradients were calculated to estimate the static pressure and kinetic energy at the inlet and outlet pipes of each junction. Finally, these inlet and outlet values were used to calculate the stagnation pressure loss coefficient, which reflects dimensionless losses of pressure and kinetic energy for the junction. These coefficients ranged from 1 to 300 for the tee junction and 1 to 400 for the wye junction over the specified range of Reynolds number. The values were inversely proportional to Reynolds number and curve fits were provided for valid ranges.
APA, Harvard, Vancouver, ISO, and other styles
7

Prapamonthon, Prasert, Bo Yin, and Guowei Yang. "Extra-Low Reynolds Number Vane Separation Using Immersed Boundary Method." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-5077.

Full text
Abstract:
Abstract Nowadays, mini unmanned aerial vehicles (MUAVs) and micro air vehicles (MAVs) are not only beneficially used as aviation models but also as modern drones for military missions and other civilian applications. Hence, research and development of propulsion sources for MUAVs and MAVs dynamically increase with a future trend of high performance, but low energy consumption. Certainly, using micro and ultra-small-size gas turbine is a good option for the propulsion source. To achieve ideal flight of MUAVs and MAVs powered by micro and ultra-small-size gas turbines under this trend, understanding of flow phenomena at wide ranges of Reynolds number is essential. This research presents a 2D numerical study of characteristics of laminar flow separation and the trailing-edge vortex on a turbine vane at extra-low Reynolds numbers (Res) i.e. Re = 1800 and 3600, and three rotational angles (α) i.e. α = 0°, 15° and 30° using immersed boundary method (IBM). With this method, the problem of incompressible flow is addressed by a sharp interface IBM. Numerical results indicate that IBM can characterize phenomena of laminar separation flow, which usually happens on the turbine airfoil when laminar boundary layer cannot overcome adverse pressure gradients and viscous effects. To our current knowledge, this may be the first research to study flow behavior at such low Res for gas turbine vanes using IBM. Even though it is now not common to operate micro and ultra-small-size gas turbines under these conditions, it is important to know how aerodynamic performance may be if micro and ultra-small-size gas turbines need to run under such conditions in the near future.
APA, Harvard, Vancouver, ISO, and other styles
8

Yang, Li, Kartikeya Tyagi, Srinath Ekkad, and Jing Ren. "Influence of Rotation on Heat Transfer in a Two-Pass Channel With Impingement Under High Reynolds Number." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42871.

Full text
Abstract:
Effect of rotation on turbine blade internal cooling is an important factor in gas turbine cooling systems. In order to minimize the impact from the Coriolis force, cooling structures with less rotation-dependent cooling effectiveness are needed. This study presents an impingement design in a two pass channel to reduce impact of rotational forces on non-uniform heat transfer behavior inside these complex channels. A Transient Liquid Crystal(TLC) method was employed to obtain local heat transfer coefficient measurements in a rotating environment. The channel Reynolds number based on the channel diameter ranges from 25,000 to 100,000. The rotation number ranges from 0 to 0.14. A series of computational simulations with the SST model were also utilized to understand the flow field behavior that impacts the heat transfer distributions on the walls. A 1-D correlation of zone averaged Nusselt number distribution was derived from the measurements. Results show that rotation reduces the heat transfer on both sides of the impingement, which is due to the Coriolis force and the pressure redistribution. The local change in the present study is about 25%. Rotation significantly enhances the heat transfer near the closed end because of the centrifugal force and the ‘pumping’ effect. Within the parameters of this test, the magnitude of enhancement is 25% to 75%. Compared to U-bended two pass channel, impingement channel has advantages in the upstream channel and the end region, but performance is not beneficial on the leading side of the downstream channel.
APA, Harvard, Vancouver, ISO, and other styles
9

Holst, D., B. Church, F. Wegner, G. Pechlivanoglou, C. N. Nayeri, and C. O. Paschereit. "Experimental Analysis of a NACA 0021 Airfoil Under Dynamic Angle of Attack Variation and Low Reynolds Numbers." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76514.

Full text
Abstract:
The wind industry needs reliable and accurate airfoil polars to properly predict wind turbine performance, especially during the initial design phase. Medium- and low-fidelity simulations directly depend on the accuracy of the airfoil data and even more so if e.g. dynamic effects are modeled. This becomes crucial if the blades of a turbine operate under stalled conditions for a significant part of the turbine’s lifetime. In addition, the design process of vertical axis wind turbines (VAWTs) needs data across the full range of angles of attack between 0 and 180 deg. Lift, drag and surface pressure distributions of a NACA 0021 airfoil equipped with surface pressure taps were investigated based on time-resolved pressure measurements. The present study discusses full range static polars and several dynamic sinusoidal pitching configurations covering two Reynolds numbers Re = 140k and 180 k, and different incidence ranges: near stall, post stall and deep stall. Various bi-stable flow phenomena are discussed based on high frequency measurements revealing large lift-fluctuations in the post and deep stall regime that exceed the maximum lift of the static polars and are not captured by averaged measurements. Detailed surface pressure distributions are discussed to provide further insight into the flow conditions and pressure development during dynamic motion. The experimental data provided within the present paper is dedicated to the scientific community for calibration and reference purposes, which in the future may lead to higher accuracy in performance predictions during the design process of wind turbines.
APA, Harvard, Vancouver, ISO, and other styles
10

Jahnke, C. C., and D. T. Valentine. "On the Recirculation Zones in a Cylindrical Container." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1251.

Full text
Abstract:
Abstract The flow field induced inside a cylindrical container by the rotation of the two end walls is described. It is shown that stagnation points leading to separation bubbles occur on the axis of rotation and/or the bottom end wall for certain ranges of the characteristic parameters; the Reynolds number, the aspect ratio of the container, and the ratio of the rotation rates of the end walls. Flow fields in a container of aspect ratio 2.0 is examined for Reynolds numbers from 100 to 3000 and ratios of the rotation rates of the top and bottom end walls from −0.10 to 1.0. For a range of ratios of the rotation rates of the top and bottom end walls and Reynolds numbers it is shown that ring vortices surrounding a columnar vortex core exist.
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Reynolds Ranges"

1

Ulitsky, M. A General Realizability Method for the Reynolds Stress for 2-Equation RANS Models. Office of Scientific and Technical Information (OSTI), June 2009. http://dx.doi.org/10.2172/1113388.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Whetstone, James R. Measurements of coefficients of discharge for concentric flange-tapped square-edged orifice meters in water over the Reynolds number range 600 to 2,700,000. Gaithersburg, MD: National Bureau of Standards, 1989. http://dx.doi.org/10.6028/nist.tn.1264.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Whetstone, James R. Measurements of coefficients of discharge for concentric flange-tapped square-edged orifice meters in natural gas over the Reynolds number range 25,000 to 16,000,000. Gaithersburg, MD: National Bureau of Standards, 1989. http://dx.doi.org/10.6028/nist.tn.1270.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Zheng, Wanzheng, and Jason Merret. Aerodynamic Survey of Novel eVTOL Configuration Using SU2. Illinois Center for Transportation, August 2022. http://dx.doi.org/10.36501/0197-9191/22-014.

Full text
Abstract:
This report summarizes computational fluid dynamics (CFD) results of electric vertical takeoff and landing (eVTOL) geometries using the SU2 Reynolds-averaged Navier-Stokes (RANS) solver. Geometries were generated based on the Smart Transportation Infrastructure Initiative (STII) Rappor 15th iteration with various rotor-installment solutions. It was found that although open rotors installed on an underwing pylon were superior to shrouded rotors installed in a canoe, the canoe configuration would provide more potential for improvement, and using a canoe door to cover the first rotor opening would reduce the drag experienced by the canoe case below that upon the rod case. Rotor doors were found to be most efficient in reducing drag of the canoe case: Average drag reduction with covering the first rotor and all rotors was 66 and 165 counts, respectively. Changing rotor distributions along the chordwise direction had minimal impact on drag reduction, and placing rotors along the spanwise direction was not advised due to the increase of the projected frontal area. Increasing canoe chord length did not have significant impact on drag reduction; and if rotor doors were implemented, increasing canoe size had negative impact on drag. Rounding rotor edges did not change the aerodynamic performance of the canoe case but promotes vertical air intake when running lifting fans. Drag received by the canoe parabolically correlated to rotor diameter, with 126 counts of drag if the rotor diameter was 0 and 377 counts if the rotor diameter was 2.95 ft. Fuselage and tail added an average 179 counts of drag, and thus the aforementioned differences were still significant in the scale of aerodynamic properties of the full configuration.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Reynolds Ranges' for particular source types:
Journal articles Dissertations / Theses
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography