Prediction of local shear stress and heat transfer between internal rotating cylinder and longitudinal cavities on stationary cylinder with various shapes

In recent years, nanofluids have attracted attention as a new generation of heat transfer fluids in building heating, heat exchangers, plants, and automotive cooling applications because of their excellent thermal performance. Various benefits of the application of nanofluids include improved heat transfer, heat transfer system size reduction, minimal clogging, microchannel cooling, and miniaturization of systems. In this paper, a study of steady, laminar, natural convection boundary-layer flow adjacent to a vertical cylinder embedded in a thermally stratified nanofluid-saturated non-Darcy porous medium is investigated. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis, and a generalized porous media model, which includes inertia and boundary effects, is employed. The cylinder surface is maintained at a constant nanoparticles volume fraction, and the wall temperature is assumed to vary with the vertical distance according to the power law form. The resulting governing equations are nondimensionalized and transformed into a nonsimilar form and then solved by Keller box method. A comparison is made with the available results in the literature, and our results are in very good agreement with the known results. A parametric study of the physical parameters is made, and a representative set of numerical results for the velocity, temperature, and volume fraction, as well as local shear stress and local Nusselt and Sherwood numbers, are presented graphically. The salient features of the results are analyzed and discussed. The results indicate that, when the buoyancy ratio or modified Grashof number increases, all of the local shear stress, local Nusselt number, and the local Sherwood number enhance while the opposite behaviors are predicted when the thermophoresis parameter increases. Moreover, increasing the value of the surface curvature parameter leads to increases in all of the local shear stress and the local Nusselt and Sherwood numbers while the opposite behaviors are obtained when either of the thermal stratification parameter or the boundary effect parameter increases.

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A New Skin Friction Meter of Floating-Element Type and the Measurements of Local Shear Stress

Journal of the Society of Naval Architects of Japan ◽

10.2534/jjasnaoe1968.1975.138_74 ◽

1975 ◽

Vol 1975 (138) ◽

pp. 74-80

Author(s):

Takio Hotta

Keyword(s):

Shear Stress ◽

Skin Friction ◽

Floating Element ◽

Local Shear ◽

Element Type ◽

New Skin ◽

Local Shear Stress

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Local shear stress measurements in the normal and diabetic foot patients during walking

World Congress on Medical Physics and Biomedical Engineering 2006 - IFMBE Proceedings ◽

10.1007/978-3-540-36841-0_748 ◽

2007 ◽

pp. 2957-2960 ◽

Cited By ~ 1

Author(s):

S. W. Park ◽

Young-Ho Kim

Keyword(s):

Shear Stress ◽

Diabetic Foot ◽

Stress Measurements ◽

Local Shear ◽

Local Shear Stress

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Experimental investigation on local shear stress and turbulence intensities over a rough non-uniform bed with and without sediment using 2D particle image velocimetry

International Journal of Sediment Research ◽

10.1016/j.ijsrc.2019.11.001 ◽

2020 ◽

Vol 35 (2) ◽

pp. 193-202 ◽

Cited By ~ 1

Author(s):

Petr Lichtneger ◽

Christine Sindelar ◽

Johannes Schobesberger ◽

Christoph Hauer ◽

Helmut Habersack

Keyword(s):

Experimental Investigation ◽

Shear Stress ◽

Particle Image Velocimetry ◽

Particle Image ◽

Image Velocimetry ◽

Local Shear ◽

Local Shear Stress

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Roughness Influence on Turbulent Flow Through Annular Seals

Journal of Tribology ◽

10.1115/1.2927219 ◽

1994 ◽

Vol 116 (2) ◽

pp. 321-328 ◽

Cited By ~ 14

Author(s):

Victor Lucas ◽

Sterian Danaila ◽

Olivier Bonneau ◽

Jean Freˆne

Keyword(s):

Surface Roughness ◽

Shear Stress ◽

Wall Shear Stress ◽

Turbulent Flow ◽

Dynamic Characteristics ◽

Reynolds Equation ◽

Mixing Length ◽

Local Shear ◽

Wall Shear ◽

Local Shear Stress

This paper deals with an analysis of turbulent flow in annular seals with rough surfaces. In this approach, our objectives are to develop a model of turbulence including surface roughness and to quantify the influence of surface roughness on turbulent flow. In this paper, in order to simplify the analysis, the inertial effects are neglected. These effects will be taken into account in a subsequent work. Consequently, this study is based on the solution of Reynolds equation. Turbulent flow is solved using Prandtl’s turbulent model with Van Driest’s mixing length expression. In Van Driest’s model, the mixing length depends on wall shear stress. However there are many numerical problems in evaluating this wall shear stress. Therefore, the goal of this work has been to use the local shear stress in the Van Driest’s model. This derived from the work of Elrod and Ng concerning Reichardt’s mixing length. The mixing length expression is then modified to introduce roughness effects. Then, the momentum equations are solved to evaluate the circumferential and axial velocity distributions as well as the turbulent viscosity μ1 (Boussinesq’s hypothesis) within the film. The coefficients of turbulence kx and kz, occurring in the generalized Reynolds’ equation, are then calculated as functions of the flow parameters. Reynolds’ equation is solved by using a finite centered difference method. Dynamic characteristics are calculated by exciting the system numerically, with displacement and velocity perturbations. The model of Van Driest using local shear stress and function of roughness has been compared (for smooth seals) to the Elrod and Ng theory. Some numerical results of the static and dynamic characteristics of a rough seal (with the same roughness on the rotor as on the stator) are presented. These results show the influence of roughness on the dynamic behavior of the shaft.

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Stress-gradient Coupling in Glacier Flow: IV. Effects of the “T” Term

Journal of Glaciology ◽

10.3189/s0022143000012016 ◽

1986 ◽

Vol 32 (112) ◽

pp. 342-349 ◽

Cited By ~ 1

Author(s):

Barclay Kamb ◽

Keith A. Echelmeyer

Keyword(s):

Shear Stress ◽

Coupling Theory ◽

Longitudinal Stress ◽

Longitudinal Flow ◽

Stress Gradients ◽

Flow Coupling ◽

Flow Response ◽

Longitudinal Variations ◽

Local Shear ◽

Local Shear Stress

AbstractThe “T term” in the longitudinal stress-equilibrium equation for glacier mechanics, a double y-integral of ∂2τxy/∂x2 where x is a longitudinal coordinate and y is roughly normal to the ice surface, can be evaluated within the framework of longitudinal flow-coupling theory by linking the local shear stress τxy at any depth to the local shear stress τB at the base, which is determined by the theory. This approach leads to a modified longitudinal flow-coupling equation, in which the modifications deriving from the T term are as follows: 1. The longitudinal coupling length is increased by about 5%. 2. The asymmetry parameter σ is altered by a variable but small amount depending on longitudinal gradients in ice thickness h and surface slope α. 3. There is a significant direct modification of the influence of local h and α on flow, which represents a distinct “driving force” in glacier mechanics, whose origin is in pressure gradients linked to stress gradients of the type ∂τxy/∂x. For longitudinal variations in h, the “T force” varies as d2h/dx2 and results in an in-phase enhancement of the flow response to the variations in h, describable (for sinusoidal variations) by a wavelength-dependent enhancement factor. For longitudinal variations in α, the “force” varies as dα/dx and gives a phase-shifted flow response. Although the “T force” is not negligible, its actual effect on τB and on ice flow proves to be small, because it is attenuated by longitudinal stress coupling. The greatest effect is at shortest wavelengths (λ 2.5h), where the flow response to variations in h does not tend to zero as it would otherwise do because of longitudinal coupling, but instead, because of the effect of the “T force”, tends to a response about 4% of what would occur in the absence of longitudinal coupling. If an effect of this small size can be considered negligible, then the influence of the T term can be disregarded. It is then unnecessary to distinguish in glacier mechanics between two length scales for longitudinal averaging of τb, one over which the T term is negligible and one over which it is not.Longitudinal flow-coupling theory also provides a basis for evaluating the additional datum-state effects of the T term on the flow perturbations Δu that result from perturbations Δh and Δα from a datum state with longitudinal stress gradients. Although there are many small effects at the ~1% level, none of them seems to stand out significantly, and at the 10% level all can be neglected.The foregoing conclusions apply for long wavelengths λh. For short wavelengths (λ h), effects of the T term become important in longitudinal coupling, as will be shown in a later paper in this series.

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