Thermal Stability of Two Fluid Layers Separated by a Solid Interlayer of Finite Thickness and Thermal Conductivity

1984 ◽  
Vol 106 (3) ◽  
pp. 605-612 ◽  
Author(s):  
I. Catton ◽  
J. H. Lienhard
Keyword(s):  
Thermal Conductivity ◽  
Fluid Layer ◽  
Heated Surface ◽  
Finite Thickness ◽  
Fluid Layers ◽  
The Stability ◽  
Stability Limits ◽  
Range Of Values ◽  
Two Fluid ◽  
Thermal Stability Of

Stability limits of two horizontal fluid layers separated by an interlayer of finite thermal conductivity are determined. The upper cooled surface and the lower heated surface are taken to be perfectly conducting. The stability limits are found to depend on the ratio of fluid layer thicknesses, the ratio of interlayer thickness to total fluid layer thickness, and the ratio of fluid thermal conductivity to interlayer thermal conductivity. Results are given for a range of values of each of the governing parameters.

Stability of gravitating fluid layer of infinite extent but finite thickness including Hall effect

1968 ◽  
Vol 46 (19) ◽  
pp. 2201-2205 ◽  
Author(s):  
K. P. Das
Keyword(s):  
Hall Effect ◽  
Hall Current ◽  
Fluid Layer ◽  
Finite Thickness ◽  
Perturbation Parameter ◽  
Displacement Current ◽  
Plane Symmetric ◽  
Infinite Extent ◽  
Mode Method ◽  
The Stability

The stability of a gravitating, homogeneous, incompressible fluid layer of infinite extent but finite thickness is considered, including Hall effect, by the use of the normal mode method. A uniform magnetic field is assumed to be present throughout parallel to its boundary. The displacement current is neglected. An asymptotic analysis for small nonzero Hall current shows a destabilizing effect of order ε where ε is the perturbation parameter. The stability analysis is restricted to plane-symmetric modes.

Capillary Instability of Viscoelastic Liquid Film With Heat and Mass Transfer

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Mukesh Kumar Awasthi
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Viscoelastic Liquid ◽  
Capillary Instability ◽  
Viscous Potential Flow ◽  
Viscous Gas ◽  
Coaxial Cylinders ◽  
Fluid Layers ◽  
The Stability ◽  
Two Fluid

Abstract This paper examines the effect of transfer of heat and mass on the capillary instability between a viscoelastic liquid and a viscous gas. The viscoelastic liquid obeys the Oldroyd B-model. These two fluid layers considered in coaxial cylinders and viscoelastic–viscous potential flow theory are used for investigation. To study the stability of the interface, the normal-mode procedure is employed and a cubic dispersion equation in terms of growth rate has been obtained. We observe that the viscoelastic liquid–viscous gas interface is more unstable than the viscous liquid–viscous gas interface. Additionally, we show that the unstable axisymmetric wave modes are stabilized by allowing heat transfer at the interface.

scholarly journals Onset of Convection in Fluid Layers with Non-uniform Volumetric Energy Sources

1979 ◽  
Vol 101 (4) ◽  
pp. 666-671 ◽  
Author(s):  
A. Yu¨cel ◽  
Y. Bayazitog˘lu
Keyword(s):  
Fluid Layer ◽  
Linear Stability Theory ◽  
Energy Sources ◽  
Convective Boundary ◽  
Onset Of Convection ◽  
Fluid Layers ◽  
Convective Motions ◽  
Fluid Body ◽  
Bounding Surfaces ◽  
Thermal Stability Of

The thermal stability of a fluid layer with non-uniform distribution of the volumetric energy sources is studied. The conditions leading to the onset of convective motions in the fluid are determined analytically by linear stability theory. The system considered consists of a fluid layer of infinite horizontal extent which is confined between two rigid parallel boundaries and subjected to general convective boundary conditions. The fluid is heated internally by way of absorption of the external radiation penetrating in the fluid body. The effects of the stabilizing and destabilizing temperature differences at the boundaries and the properties of the bounding surfaces are investigated. Optically thicker layers are found to be more stable.

scholarly journals An Analysis of Two Fluid Layers Enclosed Between Two Non-Porous Surfaces

2022 ◽  
Vol 17 ◽  
pp. 29-33
Author(s):  
Asad Salem
Keyword(s):  
Thin Sheet ◽  
Phase Interface ◽  
Complete Analysis ◽  
Hydrodynamic Models ◽  
Two Phase ◽  
Linearized Stability ◽  
Fluid Layers ◽  
The Stability ◽  
Droplet Size Distributions ◽  
Two Fluid

The stability of a two-phase interface is a crucial occurrence that involves the design of many engineering applications. It correlates the spatial and droplet size-distributions of many fluid spraying applications and has a great effect on the estimations of the critical heat flux of systems that involves phase change or evaporation. However, the existing hydrodynamic models are only able to predict the stability of a plane fluid sheet, surrounded by an infinite pool of liquid. The case of a thin sheet of liquid surrounding a vapor sheet and enclosed between two walls has not been studied yet. The present paper solves this problem using a linearized stability analysis. Velocity potentials satisfying these conditions are introduced and a complete analysis is presented.

The Effect of Suction on the Stability of Fluid between Horizontal Plates at Differing Temperatures

1985 ◽  
Vol 199 (2) ◽  
pp. 145-151 ◽  
Author(s):  
M M Sorour ◽  
M A Hassab ◽  
F A Elewa
Keyword(s):  
Rayleigh Number ◽  
Fluid Layer ◽  
Critical Rayleigh Number ◽  
Linear Stability Theory ◽  
Stability Criteria ◽  
Thermal Boundary Conditions ◽  
Wide Range ◽  
Fluid Layers ◽  
The Stability ◽  
Horizontal Fluid Layer

The linear stability theory is applied to study the effect of suction on the stability criteria of a horizontal fluid layer confined between two thin porous surfaces heated from below. This investigation covers a wide range of Reynolds number 0 ≥ Re ≥ 30, and Prandtl number 0.72 ≥ Pr ≥ 100. The results show that the critical Rayleigh number increases with Peclet number, and is independent of Pr as far as Re < 3. However, for Re > 3 the critical Rayleigh number is function of both Pr and Pe. In addition, the analysis is extended to study the effect of suction on the stability of two special superimposed fluid layers. The results in the latter case indicate a more stabilizing effect. Furthermore, the effect of thermal boundary conditions is also investigated.

Thermal Instability in Differentially Heated Inclined Fluid Layers

1972 ◽  
Vol 39 (1) ◽  
pp. 41-46 ◽  
Author(s):  
T. E. Unny
Keyword(s):  
Prandtl Number ◽  
Fluid Layer ◽  
Critical Rayleigh Number ◽  
Base Flow ◽  
Fluid Layers ◽  
Heated Fluid ◽  
The Stability ◽  
Horizontal Fluid Layer ◽  
Small Inclination

In an inclined adversely heated fluid layer confined between two rigid boundaries in a slot of large aspect ratio it is found that the unicellular base flow in the conduction regime becomes unstable with the formation of stationary secondary rolls with their axes along the line of inclination (x-rolls) for large Prandtl number fluids and axes perpendicular to the line of inclination (y-rolls) for small Prandtl number fluids. However, for angles near the vertical, the curve of the critical Rayleigh number versus inclination for x-rolls rises above that for y-rolls even for large Prandtl number fluids so that in a vertical fluid layer only cross rolls (y-rolls) could develop. The stability equations, as well as the results, reduce to those available for the horizontal fluid layer for which x-rolls are as likely to occur as y-rolls. It is seen that even a small inclination to the horizontal is enough to assign a definite direction for these two-dimensional cells, this direction depending on the Prandtl number. It is hoped that this basic information will be of help in the determination of the magnitude of the secondary cells in the postinstability regime and the heat transfer characteristics of the thin fluid layer.

An Improved Approach to Conductive Boundary Conditions for the Rayleigh-Be´nard Instability

1987 ◽  
Vol 109 (2) ◽  
pp. 378-387 ◽  
Author(s):  
J. H. Lienhard
Keyword(s):  
Thermal Conductivity ◽  
Boundary Conditions ◽  
Exact Solutions ◽  
Stability Problem ◽  
Stability Limit ◽  
Fluid Layers ◽  
The Stability ◽  
Rayleigh Numbers ◽  
Layer Problem

A technique is developed for predicting the stability limit of conductively coupled horizontal fluid layers heated from below and cooled above. The approach presented gives exact solutions of the stability problem and is numerically much simpler than previous multilayer solutions. Critical Rayleigh numbers are obtained for the case of three and four fluid layers separated by equally spaced identical midlayers of various thicknesses and conductivities with isothermal outer walls and for the symmetric two-layer problem with outer walls of finite thermal conductivity. Other configurations are considered briefly.

scholarly journals THEORETICAL STUDY OF THE STABILITY OF TWO-FLUID LAYERS

1974 ◽  
Vol 7 (2) ◽  
pp. 81-87 ◽  
Author(s):  
NOBUYUKI IMAISHI ◽  
KATSUHIKO FUJIKAWA
Keyword(s):  
Theoretical Study ◽  
Fluid Layers ◽  
The Stability ◽  
Two Fluid

An Experimental Investigation on Thermal Conductivity and Viscosity of Graphene doped CNTs /TiO2 Nanofluid

2020 ◽  
Vol 17 (3) ◽  
Author(s):  
A.M. Zetty Akhtar ◽  
M.M. Rahman ◽  
K. Kadirgama ◽  
M.A. Maleque
Keyword(s):  
Thermal Conductivity ◽  
Zeta Potential ◽  
Base Fluid ◽  
Minimum Quantity Lubrication ◽  
Cutting Fluid ◽  
Cutting Zone ◽  
Observation Method ◽  
The Stability ◽  
The Relationship ◽  
Zeta Potential Analysis

This paper presents the findings of the stability, thermal conductivity and viscosity of CNTs (doped with 10 wt% graphene)- TiO2 hybrid nanofluids under various concentrations. While the usage of cutting fluid in machining operation is necessary for removing the heat generated at the cutting zone, the excessive use of it could lead to environmental and health issue to the operators. Therefore, the minimum quantity lubrication (MQL) to replace the conventional flooding was introduced. The MQL method minimises the usage of cutting fluid as a step to achieve a cleaner environment and sustainable machining. However, the low thermal conductivity of the base fluid in the MQL system caused the insufficient removal of heat generated in the cutting zone. Addition of nanoparticles to the base fluid was then introduced to enhance the performance of cutting fluids. The ethylene glycol used as the base fluid, titanium dioxide (TiO2) and carbon nanotubes (CNTs) nanoparticle mixed to produce nanofluids with concentrations of 0.02 to 0.1 wt.% with an interval of 0.02 wt%. The mixing ratio of TiO2: CNTs was 90:10 and ratio of SDBS (surfactant): CNTs was 10:1. The stability of nanofluid checked using observation method and zeta potential analysis. The thermal conductivity and viscosity of suspension were measured at a temperature range between 30˚C to 70˚C (with increment of 10˚C) to determine the relationship between concentration and temperature on nanofluid’s thermal physical properties. Based on the results obtained, zeta potential value for nanofluid range from -50 to -70 mV indicates a good stability of the suspension. Thermal conductivity of nanofluid increases as an increase of temperature and enhancement ratio is within the range of 1.51 to 4.53 compared to the base fluid. Meanwhile, the viscosity of nanofluid shows decrements with an increase of the temperature remarks significant advantage in pumping power. The developed nanofluid in this study found to be stable with enhanced thermal conductivity and decrease in viscosity, which at once make it possible to be use as nanolubricant in machining operation.

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