A Numerical Method for Calculating Fully Developed Laminar Velocity Profiles From Temperature Profiles

1970 ◽  
Vol 92 (2) ◽  
pp. 245-251 ◽  
Author(s):  
L. O. Billig ◽  
K. R. Galle
Keyword(s):  
Velocity Profile ◽  
Computer Program ◽  
Numerical Method ◽  
Temperature Profile ◽  
Velocity Profiles ◽  
Temperature Profiles ◽  
Reasonable Accuracy ◽  
Experimental Errors ◽  
Calculated Velocity

It is noted that the velocity profile has a significant effect on the temperature profile that develops in a fluid flowing through a tube. A numerical method for retrieving the velocity profile from a temperature profile is given and the computer program written to implement the method is described. The method retrieved velocity profiles of reasonable accuracy from temperature profiles calculated from the Graetz solution and by Kays’ numerical method. The results of a study to estimate the effects of possible experimental errors from several possible sources on the calculated velocity profiles are included.

A new method of determining the transport coefficients for high pressure arcs from experimental data

1969 ◽  
Vol 3 (2) ◽  
pp. 269-280 ◽  
Author(s):  
L. B. Kapp ◽  
P. H. Richards
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Computer Program ◽  
Numerical Method ◽  
Temperature Profile ◽  
Transport Coefficients ◽  
New Method ◽  
Radial Temperature ◽  
Current Voltage ◽  
Current Voltage Characteristics

The problem is to determine the electrical and thermal conductivities of high pressure are plasmas from measurements of the current—voltage characteristics of the are and a single radial temperature profile. A new numerical method is described together with the corresponding computer program. The latter is applied to some recent measurements on wall-stabilized nitrogen ares, covering the temperature range 4500—11,000 °K, for which radiation can be neglected, and the results are compared with those of other workers.

Power Law Velocity and Temperature Profiles in a Fully Developed Turbulent Channel Flow

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
Abu Seena ◽  
Noor Afzal
Keyword(s):  
Heat Transfer ◽  
Velocity Profile ◽  
Temperature Profile ◽  
Channel Flow ◽  
Power Law ◽  
Turbulent Channel Flow ◽  
Temperature Profiles ◽  
Fully Developed Turbulent Flow ◽  
Friction Temperature ◽  
Log Law

Abstract The power law temperature distribution in a fully developed turbulent channel flow for large Peclet numbers has been proposed in the present work. The analysis of the power law velocity profile in a fully developed mean turbulent channel flow would be used for carrying out the analysis of the power law temperature profile. The Reynolds mean thermal energy equation in a fully developed mean turbulent channel flow has been analyzed. The mean turbulent thermal flow is divided in the inner and outer thermal layers that have been matched by Izakson–Millikan–Kolmogorov hypothesis to get the power law temperature profiles and the power law heat transfer law in the overlap region, in addition to traditional log laws for temperature profiles and heat transfer. It has been shown that the envelope of the heat transfer power law gives the heat transfer log law. Further, it is shown that the temperature power law index and prefactor are functions of the friction Peclet number, as well as function of an alternate variable, the nondimensional friction temperature. It is shown that for large Peclet numbers the power law temperature profile is equivalent to the log law temperature profile. The direct numerical simulation velocity profile data of fully developed turbulent flow provide good support for the power law temperature profile theory.

scholarly journals The dam-break problem for concentrated suspensions of neutrally buoyant particles

2013 ◽  
Vol 724 ◽  
pp. 95-122 ◽  
Author(s):  
C. Ancey ◽  
N. Andreini ◽  
G. Epely-Chauvin
Keyword(s):  
Velocity Profile ◽  
Newtonian Fluid ◽  
Velocity Profiles ◽  
Lubrication Theory ◽  
Dam Break ◽  
Particle Migration ◽  
Flow Depth ◽  
Concentrated Suspensions ◽  
Front Position ◽  
Neutrally Buoyant

AbstractThis paper addresses the dam-break problem for particle suspensions, that is, the flow of a finite volume of suspension released suddenly down an inclined flume. We were concerned with concentrated suspensions made up of neutrally buoyant non-colloidal particles within a Newtonian fluid. Experiments were conducted over wide ranges of slope, concentration and mass. The major contributions of our experimental study are the simultaneous measurement of local flow properties far from the sidewalls (velocity profile and, with lower accuracy, particle concentration) and macroscopic features (front position, flow depth profile). To that end, the refractive index of the fluid was adapted to closely match that of the particles, enabling data acquisition up to particle volume fractions of 60 %. Particle migration resulted in the blunting of the velocity profile, in contrast to the parabolic profile observed in homogeneous Newtonian fluids. The experimental results were compared with predictions from lubrication theory and particle migration theory. For solids fractions as large as 45 %, the flow behaviour did not differ much from that of a homogeneous Newtonian fluid. More specifically, we observed that the velocity profiles were closely approximated by a parabolic form and there was little evidence of particle migration throughout the depth. For particle concentrations in the 52–56 % range, the flow depth and front position were fairly well predicted by lubrication theory, but taking a closer look at the velocity profiles revealed that particle migration had noticeable effects on the shape of the velocity profile (blunting), but had little impact on its strength, which explained why lubrication theory performed well. Particle migration theories (such as the shear-induced diffusion model) successfully captured the slow evolution of the velocity profiles. For particle concentrations in excess of 56 %, the macroscopic flow features were grossly predicted by lubrication theory (to within 20 % for the flow depth, 50 % for the front position). The flows seemed to reach a steady state, i.e. the shape of the velocity profile showed little time dependence.

scholarly journals Constraints on glacier flow from temperature-depth profiles in the ice. Application to EPICA Dome C.

2016 ◽  
Author(s):  
Ignacio Hermoso de Mendoza ◽  
Jean-Claude Mareschal ◽  
Hugo Beltrami
Keyword(s):  
Heat Flux ◽  
Velocity Profile ◽  
Boundary Conditions ◽  
Temperature Profile ◽  
East Antarctica ◽  
Surface Velocity ◽  
Function Parameter ◽  
Unknown Parameters ◽  
Conduction Model ◽  
Ice Flow

Abstract. A one-dimensional (1-D) ice flow and heat conduction model is used to calculate the temperature and heat flux profiles in the ice and to constrain the parameters characterizing the ice flow and the thermal boundary conditions at the Dome C drilling site in East Antarctica. We use the reconstructions of ice accumulation, glacier height and air surface temperature histories as boundary conditions to calculate the ice temperature profile. The temperature profile also depends on a set of poorly known parameters, the ice velocity profile and magnitude, basal heat flux, and air-ice surfaces temperature coupling. We use Monte Carlo methods to search the parameters' space of the model, compare the model output with the temperature data, and find probability distributions for the unknown parameters. We could not determine the sliding ratio because it has no effect on the thermal profile, but we could constrain the flux function parameter p that determines the velocity profile. We determined the basal heat flux qb = 49.0  ± 2.7 (2σ)m W m−2, almost equal to the apparent value. We found an ice surface velocity of vsur = 2.6 ± 1.9 (2σ)m y−1 and an air-ice temperature coupling of 0.8 ± 1.0(2σ)K. Our study confirms that the heat flux is low and does not destabilize the ice sheet in east Antarctica.

scholarly journals A new method to derive middle atmospheric temperature profiles using a combination of Rayleigh lidar and O<sub>2</sub> airglow temperatures measurements

2012 ◽  
Vol 30 (1) ◽  
pp. 27-32 ◽  
Author(s):  
A. Taori ◽  
A. Jayaraman ◽  
K. Raghunath ◽  
V. Kamalakar
Keyword(s):  
Temperature Profile ◽  
Atmospheric Temperature ◽  
New Method ◽  
Temperature Profiles ◽  
Vertical Temperature ◽  
Lidar System ◽  
Mesospheric Temperature ◽  
Simultaneous Measurements ◽  
Rayleigh Lidar ◽  
First Time

Abstract. The vertical temperature profiles in a typical Rayleigh lidar system depends on the backscatter photon counts and the CIRA-86 model inputs. For the first time, we show that, by making simultaneous measurements of Rayleigh lidar and upper mesospheric O2 temperatures, the lidar capability can be enhanced to obtain mesospheric temperature profile up to about 95 km altitudes. The obtained results are compared with instantaneous space-borne SABER measurements for a validation.

scholarly journals New Infrared Diffuse Interstellar Bands in the Galactic Center and Elsewhere

2013 ◽  
Vol 9 (S297) ◽  
pp. 64-67
Author(s):  
T. R. Geballe
Keyword(s):  
Velocity Profile ◽  
Galactic Center ◽  
Velocity Profiles ◽  
Significant Fraction ◽  
Diffuse Interstellar Bands ◽  
The Galaxy ◽  
Band Spectra

AbstractThis paper updates the recent discovery of over a dozen new diffuse interstellar bands (DIBs), first in H-band spectra of stars in the Galactic center (GC) and toward stars in the Cygnus OB2 Association. The H-band DIBs, which currently number 15, are the longest wavelength DIBs reported to date and are the first found on sightlines toward the Galactic center. K-band (2.0-2.5 μm) spectra of the GC stars do not reveal additional DIBs. Comparison of the velocity profile of the strongest of the new DIBs in the sightline toward GCS3-2 (in the GC) with that toward Cygnus OB2 No. 9 and also with the broad velocity profiles of H3+ lines toward GCS3-2 confirm that a significant fraction of the diffuse material producing the DIB absorptions on sightlines to the GC is located within the central few hundred parsecs of the Galaxy.

INFLUENCE OF CALORIMETRIC MIXING ON THE TEMPERATURE PROFILE WHEN EVALUATING WORKING INTERVALS

2021 ◽  
Author(s):  
Марат Финатович Закиров ◽  
Айрат Шайхуллинович Рамазанов ◽  
Рим Абдуллович Валиуллин ◽  
Рамиль Фаизырович Шарафутдинов
Keyword(s):  
Temperature Profile ◽  
Temperature Profiles ◽  
Measured Temperature ◽  
Vertical Wells

В данной работе исследуется профиль термограммы в зависимости от производительности работающих интервалов вертикальной скважины. Установлено, что существуют уникальные профили температур в зависимости от проявления эффекта калориметрического смешивания. Полученные результаты могут быть использованы для анализа экспериментальных профилей температуры с целью выделения работающих интервалов. In this paper, the thermogram profile is studied depending on the performance of the working intervals of the vertical wells. It is established that there are unique temperature profiles depending on the manifestation of calorimetric mixing. The obtained results can be used to analyze measured temperature profiles in order to identify working intervals.

Lattice Boltzmann modeling of convective flows in a large-scale cavity heated from below by two imposed temperature profiles

2019 ◽  
Vol 30 (5) ◽  
pp. 2759-2779
Author(s):  
Noureddine Abouricha ◽  
Mustapha El Alami ◽  
Khalid Souhar
Keyword(s):  
Nusselt Number ◽  
Temperature Profile ◽  
Lattice Boltzmann ◽  
Large Scale ◽  
Temperature Profiles ◽  
Control Parameters ◽  
Content Type ◽  
Convective Flows ◽  
Glass Door ◽  
Vertical Walls

Purpose The purpose of this paper is to model the convective flows in a room equipped by a glass door and a heated floor of length l = 0.8 × H and submitted to a sinusoidal temperature profile and mono alternative temperature profile. Design/methodology/approach The paper opts for a numerical study of convective flows in a large scale cavity using the Lattice Boltzmann Method (LBM) by considering a two dimensions (2D) square cavity of side H and filled by air (Pr = 0.71). All the vertical walls, the ceiling and the rest of the floor are thermally insulated, the hot portion of length l = 0.8×H is heated with two imposed temperature profiles of amplitude values 0.2 ≤  a  ≤ 0.6 and for two different periods ζ = ζ0 and ζ = 0.4×ζ0. One of the vertical walls has a cold portion θc = 0 that represents the glass door. Findings A systematic study of the flow structure and heat transfer is carried out considering principal control parameters: amplitude “a” and period ζ for Rayleigh number Ra = 108. Effects of these parameters on results are presented in terms of isotherms, streamlines, profiles of velocities, temperature in the cavity, global and local Nusselt number. It has been found that an increase in amplitude or period increases the amplitude of the temperature in the core of cavity. The Nusselt number increases when the amplitude “a” of the imposed temperature increases, but this later is not affected by variation of the period. Originality/value The authors used LBM to simulate the convective flows in a cavity at high Ra, heated from below by tow imposed temperature profiles. Indeed, they simulate a local equipped by a solar water heater (SWH). The floor is subjected to a periodic heating: Sinusoidal heating (Case 1) for which the temperature varies sinusoidally (SWH without a supplement), and mono alternation heating (Case 2), the temperature evolves like a redressed signal (SWH with a supplement). The considered method has been successfully validated and compared with the previous work. The study has been conducted using several control parameters such as the signal amplitude and period in the case of turbulent convection. This allowed us to obtain a considerable set of results that can be used for engineering.

Velocity Profiles of Turbulent Boundary Layers

1969 ◽  
Vol 73 (698) ◽  
pp. 143-147 ◽  
Author(s):  
M. K. Bull
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Velocity Profile ◽  
Boundary Layers ◽  
Experimental Work ◽  
Constant Pressure ◽  
Velocity Profiles ◽  
Turbulent Boundary Layers ◽  
Boundary Layer Equations

Although a numerical solution of the turbulent boundary-layer equations has been achieved by Mellor and Gibson for equilibrium layers, there are many occasions on which it is desirable to have closed-form expressions representing the velocity profile. Probably the best known and most widely used representation of both equilibrium and non-equilibrium layers is that of Coles. However, when velocity profiles are examined in detail it becomes apparent that considerable care is necessary in applying Coles's formulation, and it seems to be worthwhile to draw attention to some of the errors and inconsistencies which may arise if care is not exercised. This will be done mainly by the consideration of experimental data. In the work on constant pressure layers, emphasis tends to fall heavily on the author's own data previously reported in ref. 1, because the details of the measurements are readily available; other experimental work is introduced where the required values can be obtained easily from the published papers.

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