A Note on Laminar Flow in Uniformly Porous Tubes

1993 ◽  
Vol 115 (3) ◽  
pp. 493-496 ◽  
Author(s):  
K. Schnitzlein
Keyword(s):  
Numerical Analysis ◽  
Laminar Flow ◽  
Incompressible Flow ◽  
Entire Range ◽  
Reynolds Numbers ◽  
Tube Axis ◽  
Similarity Condition ◽  
Asymmetric Behavior ◽  
Constant Diameter ◽  
Steady Laminar

A numerical analysis of the steady, laminar, incompressible flow in a constant diameter tube with uniform mass suction at the wall is made to study the development of the flow for the entire range of wall Reynolds numbers. It is shown that for small suction rates the state of flow can reach the similarity condition at least at distinct positions at the tube axis. For higher suction rates similarity profiles are found to occur only if the flow exhibits an asymmetric behavior with respect to the point of complete mass extraction.

Steady Laminar Flow through Twisted Pipes: Fluid Flow in Square Tubes

1981 ◽  
Vol 103 (4) ◽  
pp. 785-790 ◽  
Author(s):  
J. H. Masliyah ◽  
K. Nandakumar
Keyword(s):  
Laminar Flow ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Dissipation Term ◽  
Axial Velocity Profile ◽  
Secondary Motion ◽  
Qualitative Nature ◽  
Flow Through ◽  
Steady Laminar

The Navier-Stokes equation in a rotating frame of reference is solved numerically to obtain the flow field for a steady, fully developed laminar flow of a Newtonian fluid in a twisted tube having a square cross-section. The macroscopic force and energy balance equations and the viscous dissipation term are presented in terms of variables in a rotating reference frame. The computed values of friction factor are presented for dimensionless twist ratios, (i.e., length of tube over a rotation of π radians normalized with respect to half the width of tube) of 20, 10, 5 and 2.5 and for Reynolds numbers up to 2000. The qualitative nature of the axial velocity profile was observed to be unaffected by the swirling motion. The secondary motion was found to be most important near the wall.

A Numerical Investigation of Laminar Flow Past Nonspherical Solids and Droplets

1995 ◽  
Vol 117 (1) ◽  
pp. 170-175 ◽  
Author(s):  
J. K. Comer ◽  
C. Kleinstreuer
Keyword(s):  
Laminar Flow ◽  
Drag Coefficient ◽  
Reynolds Numbers ◽  
Shear Stresses ◽  
Spherical Droplet ◽  
Total Drag ◽  
Interfacial Transport ◽  
Aspect Ratios ◽  
Flow Past ◽  
Steady Laminar

Steady laminar flow past solitary spheroids and nonspherical droplets has been numerically analyzed. Specifically, interfacial transport properties such as surface pressures, interfacial velocities, shear stresses and separation angles as well as the resulting drag coefficients are evaluated for specified aspect ratios (0.2 ≤ E = b/a ≤ 1.0) and intermediate gas stream Reynolds numbers (40 ≤ Re ≤ 120). For one case, it was determined that the use of the traditional spherical-droplet assumption would result in a 30 percent underprediction of the total drag coefficient.

Steady laminar flow of liquid–liquid jets at high Reynolds numbers*

1993 ◽  
Vol 5 (7) ◽  
pp. 1703-1717 ◽  
Author(s):  
John R. Richards ◽  
Antony N. Beris ◽  
Abraham M. Lenhoff
Keyword(s):  
Laminar Flow ◽  
Reynolds Numbers ◽  
Liquid Jets ◽  
High Reynolds Numbers ◽  
High Reynolds ◽  
Steady Laminar

Symbolic Calculation of Laminar Convection in Uniformly Heated Horizontal Pipe at High Prandtl Number

2010 ◽  
Author(s):  
Kamyar Mansour
Keyword(s):  
Laminar Flow ◽  
Prandtl Number ◽  
Reynolds Numbers ◽  
Similarity Parameter ◽  
Horizontal Pipe ◽  
Symbolic Calculation ◽  
High Prandtl Number ◽  
Flow Through ◽  
Laminar Convection ◽  
Steady Laminar

We consider fully developed steady laminar flow through a uniformly heated horizontal pipe is simplified by assuming infinite Prandtl number. The solution is expanded in powers of a single combined similarity parameter which is the product of the Prandtl, Rayleigh, and Reynolds numbers and the series extended by means of symbolic calculation up to 16 terms. Analysis of these expansions allows the exact computation for arbitrarily accuracy up to 50000 figures. Although the range of exactness is almost the same order of the radius of convergence but Pade approximation lead our result to be good even for much higher value of the similarity parameter.

Laminar flow through a slowly rotating straight pipe

1985 ◽  
Vol 150 ◽  
pp. 1-21 ◽  
Author(s):  
Kamyar Mansour
Keyword(s):  
Boundary Layer ◽  
Laminar Flow ◽  
Reynolds Numbers ◽  
Similarity Parameter ◽  
Low Reynolds Numbers ◽  
Boundary Layer Analysis ◽  
Layer Analysis ◽  
Square Root Singularity ◽  
Flow Through ◽  
Steady Laminar

We consider fully developed steady laminar flow through a pipe that is rotating slowly about a line perpendicular to its own axis. The solution is expanded for low Reynolds numbers in powers of a single combined similarity parameter and the series extended to 34 terms by computer. Analysis shows that convergence is limited by a square-root singularity on the negative real axis of the similarity parameter. An Euler transformation and extraction of the leading, secondary and tertiary singularities at infinity render the series accurate for all values of the similarity parameter. The major conclusion of this investigation is that the friction ratio in a slowly rotating pipe grows asymptotically as the ⅛ power of the similarity parameter and not as the ¼ power as previously deduced from boundary-layer analysis. This discrepancy between the present computer-extended method and boundary-layer analysis has also occurred in the similar problem of flow through a loosely coiled pipe (Van Dyke 1978).

Heat transfer enhancement using second mode self-oscillating structures

2019 ◽  
Vol 30 (7) ◽  
pp. 3827-3842
Author(s):  
Samer Ali ◽  
Zein Alabidin Shami ◽  
Ali Badran ◽  
Charbel Habchi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Flow Regime ◽  
Vortex Generator ◽  
Reynolds Numbers ◽  
Content Type ◽  
Laminar Flow Regime ◽  
Second Mode

Purpose In this paper, self-sustained second mode oscillations of flexible vortex generator (FVG) are produced to enhance the heat transfer in two-dimensional laminar flow regime. The purpose of this study is to determine the critical Reynolds number at which FVG becomes more efficient than rigid vortex generators (RVGs). Design/methodology/approach Ten cases were studied with different Reynolds numbers varying from 200 to 2,000. The Nusselt number and friction coefficients of the FVG cases are compared to those of RVG and empty channel at the same Reynolds numbers. Findings For Reynolds numbers higher than 800, the FVG oscillates in the second mode causing a significant increase in the velocity gradients generating unsteady coherent flow structures. The highest performance was obtained at the maximum Reynolds number for which the global Nusselt number is improved by 35.3 and 41.4 per cent with respect to empty channel and rigid configuration, respectively. Moreover, the thermal enhancement factor corresponding to FVG is 72 per cent higher than that of RVG. Practical implications The results obtained here can help in the design of novel multifunctional heat exchangers/reactors by using flexible tabs and inserts instead of rigid ones. Originality/value The originality of this paper is the use of second mode oscillations of FVG to enhance heat transfer in laminar flow regime.

Heat Transfer in a Surfactant Drag-Reducing Solution—A Comparison With Predictions for Laminar Flow

2005 ◽  
Vol 128 (6) ◽  
pp. 557-563 ◽  
Author(s):  
Paul L. Sears ◽  
Libing Yang
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Reynolds Numbers ◽  
High Heat ◽  
High Heat Flux ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
Drag Reducing Additive ◽  
Good Agreement

Heat transfer coefficients were measured for a solution of surfactant drag-reducing additive in the entrance region of a uniformly heated horizontal cylindrical pipe with Reynolds numbers from 25,000 to 140,000 and temperatures from 30to70°C. In the absence of circumferential buoyancy effects, the measured Nusselt numbers were found to be in good agreement with theoretical results for laminar flow. Buoyancy effects, manifested as substantially higher Nusselt numbers, were seen in experiments carried out at high heat flux.

Laminar Flow in a Cylindrical Container With a Rotating Cover

1982 ◽  
Vol 104 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Manlio Bertela` ◽  
Fabio Gori
Keyword(s):  
Laminar Flow ◽  
Aspect Ratio ◽  
Steady Flow ◽  
Reynolds Numbers ◽  
Cylindrical Container ◽  
Cylindrical Chamber ◽  
Flow Rates ◽  
Pressure Fields

Unsteady and steady flow in a cylindrical chamber with a rotating cover has been studied for two Reynolds numbers and three aspect ratio values. The structure of the velocity and pressure fields in the apparatus is described. Primary and secondary volumetric flow rates and torque coefficients are also calculated for all six cases solved.

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