Correlated Compressible and Incompressible Channel Flows

1997 ◽  
Vol 119 (4) ◽  
pp. 911-915 ◽  
Author(s):  
C. Crnojevic´ ◽  
V. D. Djordjevic´
Keyword(s):  
Cross Section ◽  
High Reynolds Number ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Isothermal Flow ◽  
Governing Equations ◽  
Adiabatic Flow ◽  
High Reynolds Numbers ◽  
High Reynolds ◽  
Reynolds Number Flows

Compressible flow in channels of slowly varying cross section at moderately high Reynolds numbers is treated in the paper by employing some Stewartson-type transformations that convert the problem into an incompressible one. Both adiabatic flow and isothermal flow are considered, and a Poiseuille-type incompressible solution is mapped onto compressible plane in order to generate some exact solutions of the compressible governing equations. The results show striking effects that viscosity may have upon the flow characteristics in this case, in comparison with more conventional high Reynolds number flows.

AN INITIAL STUDY OF THE FLOW AROUND AN AEROFOIL AT HIGH REYNOLDS NUMBERS USING CONTINUATION

2012 ◽  
Vol 22 (10) ◽  
pp. 1250255 ◽  
Author(s):  
C. WALES ◽  
A. GAITONDE ◽  
D. JONES
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Solution Space ◽  
Reynolds Numbers ◽  
Initial Study ◽  
Continuation Methods ◽  
High Reynolds Numbers ◽  
Large Systems ◽  
High Reynolds ◽  
Reynolds Number Flows

Nonlinearities are an important feature of high Reynolds numbers flows about aircraft. Standard time stepping schemes, used in computational fluid dynamics simulations, are unable to capture the whole solution space, breaking down in the region of bifurcations. The extension of continuation techniques to such flows is therefore attractive. CFD schemes yield large systems of equations and the associated difficulties of applying continuation methods to such large systems need to be overcome. Whilst previous studies of fluids using continuation have been published, these are mainly limited to much lower Reynolds numbers. In high Reynolds number flows, inertial forces dominate and turbulence must be modeled. This study has shown that continuation can be used effectively for high Reynolds number flows demonstrated through the presentation of a number of test cases.

An Intermittent High-Reynolds-Number Wind Tunnel

1977 ◽  
Vol 28 (4) ◽  
pp. 259-264 ◽  
Author(s):  
J L Stollery ◽  
A V Murthy
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
High Reynolds Number ◽  
Reynolds Numbers ◽  
Simple Method ◽  
High Reynolds Numbers ◽  
Reservoir Conditions ◽  
High Reynolds ◽  
Cryogenic Wind Tunnel ◽  
Performance Estimates

SummaryThe paper suggests a simple method of generating intermittent reservoir conditions for an intermittent, cryogenic wind tunnel. Approximate performance estimates are given and it is recommended that further studies be made because this type of tunnel could be valuable in increasing the opportunities for research at high Reynolds numbers.

scholarly journals Lattice Boltzmann Method Simulations of High Reynolds Number Flows Past Porous Obstacles

2019 ◽  
Vol 11 (03) ◽  
pp. 1950028 ◽  
Author(s):  
N. M. Sangtani Lakhwani ◽  
F. C. G. A. Nicolleau ◽  
W. Brevis
Keyword(s):  
Reynolds Number ◽  
Lattice Boltzmann Method ◽  
Turbulent Flows ◽  
Lattice Boltzmann ◽  
High Reynolds Number ◽  
Reynolds Numbers ◽  
Navier Stokes Equation ◽  
High Reynolds ◽  
Boltzmann Method ◽  
Reynolds Number Flows

Lattice Boltzmann Method (LBM) simulations for turbulent flows over fractal and non-fractal obstacles are presented. The wake hydrodynamics are compared and discussed in terms of flow relaxation, Strouhal numbers and wake length for different Reynolds numbers. Three obstacle topologies are studied, Solid (SS), Porous Regular (PR) and Porous Fractal (FR). In particular, we observe that the oscillation present in the case of the solid square can be annihilated or only pushed downstream depending on the topology of the porous obstacle. The LBM is implemented over a range of four Reynolds numbers from 12,352 to 49,410. The suitability of LBM for these high Reynolds number cases is studied. Its results are compared to available experimental data and published literature. Compelling agreements between all three tested obstacles show a significant validation of LBM as a tool to investigate high Reynolds number flows in complex geometries. This is particularly important as the LBM method is much less time consuming than a classical Navier–Stokes equation-based computing method and high Reynolds numbers need to be achieved with enough details (i.e., resolution) to predict for example canopy flows.

Turbulent boundary layer statistics at very high Reynolds number

2015 ◽  
Vol 779 ◽  
pp. 371-389 ◽  
Author(s):  
M. Vallikivi ◽  
M. Hultmark ◽  
A. J. Smits
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
High Reynolds Number ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Mean Velocity ◽  
High Reynolds Numbers ◽  
Layer Flow ◽  
High Reynolds ◽  
Very High

Measurements are presented in zero-pressure-gradient, flat-plate, turbulent boundary layers for Reynolds numbers ranging from $\mathit{Re}_{{\it\tau}}=2600$ to $\mathit{Re}_{{\it\tau}}=72\,500$ ($\mathit{Re}_{{\it\theta}}=8400{-}235\,000$). The wind tunnel facility uses pressurized air as the working fluid, and in combination with MEMS-based sensors to resolve the small scales of motion allows for a unique investigation of boundary layer flow at very high Reynolds numbers. The data include mean velocities, streamwise turbulence variances, and moments up to 10th order. The results are compared to previously reported high Reynolds number pipe flow data. For $\mathit{Re}_{{\it\tau}}\geqslant 20\,000$, both flows display a logarithmic region in the profiles of the mean velocity and all even moments, suggesting the emergence of a universal behaviour in the statistics at these high Reynolds numbers.

Vortex Formation for Different Geometry of Cavities Using High Reynolds Number

2014 ◽  
Vol 699 ◽  
pp. 416-421
Author(s):  
Mohd Noor Asril Saadun ◽  
Muhammad Zulhakim Sharudin ◽  
Nor Azwadi Che Sidik ◽  
Mohd Hafidzal Mohd Hanafi
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Stokes Equations ◽  
Vortex Formation ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Contaminant Removal ◽  
Navier Stokes Equations ◽  
High Reynolds

A preliminary study of Computational Fluid Dynamics (CFD) on the effect of high Reynolds numbers in the cavity has been carried out. Two dimensional model analysis of the flow characteristics were conducted using the numerical solution of Navier-Stokes equations based on the finite difference method. The flow characteristics in the cavity and the driven flow were modeled via turbulence equation modelling. This paper focuses on the effects of different high Reynolds number on the flow pattern of contaminant removal in the cavity. Different types of geometry and aspect ratio of the geometry were used as the parameters of the cavity in this study. Based on visualization of flows between each model with the different parameters used, the results of a comparison analysis focusing on the behavior of the flow were reported.

Heat Transfer in a Rotating, Blade-Shaped Serpentine Cooling Passage With Discrete Ribbed Walls at High Reynolds Numbers

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Lesley M. Wright ◽  
Shang-Feng Yang ◽  
Hao-Wei Wu ◽  
Je-Chin Han ◽  
Ching-Pang Lee ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Reynolds Number ◽  
Reynolds Numbers ◽  
Pressure Side ◽  
Transfer Coefficients ◽  
First Passage ◽  
Heat Transfer Coefficients ◽  
The Third ◽  
High Reynolds Numbers ◽  
High Reynolds

Abstract This paper experimentally investigates the effect of rotation on heat transfer in a typical turbine blade, three-pass, serpentine coolant channel with discrete ribbed walls at high Reynolds numbers. To achieve the high Reynolds number (Re → 190,000) and low rotation number conditions, pressurized Freon R-134a vapor is utilized as the working fluid. Cooling flow in the first passage is radial outward; after the 180 deg tip turn, the flow is radial inward through the second passage; and after the 180 deg hub turn, the flow is radial outward in the third passage. The effects of rotation on the heat transfer coefficients were investigated at rotation numbers as low as 0.07 and Reynolds numbers from 85,000 to 187,000 (based on the first passage geometry and flow conditions). Heat transfer coefficients were measured using thermocouples embedded in copper plates to provide regionally averaged heat transfer coefficients. Heat transfer enhancement due to rotation is observed on the first passage, pressure-side with radially outward flow and the second passage, suction-side with radially inward flow, but a reduction in heat transfer is observed on the third passage pressure-side with radially outward flow. In addition, results from the discrete, broken ribs are compared with those from the same serpentine coolant passage with conventional, angled ribbed walls. A significant increase in the heat transfer due to the discrete ribs is observed in the first passage. These results can be useful for understanding real rotor blade coolant passage heat transfer under high Reynolds number and low rotation number conditions.

scholarly journals Revisiting Batchelor's theory of two-dimensional turbulence

2007 ◽  
Vol 591 ◽  
pp. 379-391 ◽  
Author(s):  
DAVID G. DRITSCHEL ◽  
CHUONG V. TRAN ◽  
RICHARD K. SCOTT
Keyword(s):  
Reynolds Number ◽  
Mathematical Analysis ◽  
High Reynolds Number ◽  
Reynolds Numbers ◽  
Inertial Range ◽  
Two Dimensional ◽  
Simple Modification ◽  
High Reynolds Numbers ◽  
Decaying Turbulence ◽  
High Reynolds

Recent mathematical results have shown that a central assumption in the theory of two-dimensional turbulence proposed by Batchelor (Phys. Fluids, vol. 12, 1969, p. 233) is false. That theory, which predicts a χ2/3k−1 enstrophy spectrum in the inertial range of freely-decaying turbulence, and which has evidently been successful in describing certain aspects of numerical simulations at high Reynolds numbers Re, assumes that there is a finite, non-zero enstrophy dissipation χ in the limit of infinite Re. This, however, is not true for flows having finite vorticity. The enstrophy dissipation in fact vanishes.We revisit Batchelor's theory and propose a simple modification of it to ensure vanishing χ in the limit Re → ∞. Our proposal is supported by high Reynolds number simulations which confirm that χ decays like 1/ln Re, and which, following the time of peak enstrophy dissipation, exhibit enstrophy spectra containing an increasing proportion of the total enstrophy 〈ω2〉/2 in the inertial range as Re increases. Together with the mathematical analysis of vanishing χ, these observations motivate a straightforward and, indeed, alarmingly simple modification of Batchelor's theory: just replace Batchelor's enstrophy spectrum χ2/3k−1 with 〈ω2〉 k−1 (ln Re)−1).

Similarity Formulations for Turbulent Boundary Layers at High Reynolds Numbers

2003 ◽  
Author(s):  
Gary J. Kunkel ◽  
Ivan Marusic
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulence Intensity ◽  
High Reynolds Number ◽  
Reynolds Numbers ◽  
Mean Flow ◽  
Mixed Flow ◽  
High Reynolds Numbers ◽  
High Reynolds ◽  
New Formulation

Data obtained from the high Reynolds number atmospheric boundary layer are used to analyze existing mean-flow and turbulence intensity similarity formulations. From the results of this analysis a new streamwise turbulence intensity formulation is proposed that is suggested to be applicable across the entire smooth-wall high Reynolds number turbulent boundary layer. The new formulation is also shown to be consistent with the mixed-flow scaling suggested by other studies.

Computation of the flow between two rotating coaxial disks

1977 ◽  
Vol 81 (4) ◽  
pp. 689-699 ◽  
Author(s):  
M. Holodniok ◽  
M. Kubicek ◽  
V. Hlavácek
Keyword(s):  
Rigid Body ◽  
Physical Interpretation ◽  
Reynolds Numbers ◽  
Main Body ◽  
Rotating Disks ◽  
Governing Equations ◽  
High Reynolds Numbers ◽  
Newton Raphson ◽  
High Reynolds ◽  
Raphson Method

A numerical investigation of the problem of rotating disks is made using the Newton–Raphson method. It is shown that the governing equations may exhibit one, three or five solutions. A physical interpretation of the calculated profiles will be presented. The results computed reveal that both Batchelor and Stewartson analysis yields for high Reynolds numbers results which are in agreement with our observations, i.e. the fluid may rotate as a rigid body or the main body of the fluid may be almost at rest, respectively. Occurrence of a two-cell situation at particular branches will be discussed.

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