scholarly journals Study of Slip Effects in Reverse Roll Coating Process Using Non-Isothermal Couple Stress Fluid

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1249
Author(s):  
Hasan Shahzad ◽  
Xinhua Wang ◽  
Muhammad Bilal Hafeez ◽  
Zahir Shah ◽  
Ahmed Mohammed Alshehri
Keyword(s):  
Pressure Gradient ◽  
Flow Rate ◽  
Couple Stress ◽  
Velocity Ratio ◽  
Closed Form Solution ◽  
Couple Stress Fluid ◽  
Slip Parameter ◽  
Roll Coating ◽  
Stress Parameter ◽  
The Impact

The non-isothermal couple stress fluid inside a reverse roll coating geometry is considered. The slip condition is considered at the surfaces of the rolls. To develop the flow equations, the mathematical modelling is performed using conservation of momentum, mass, and energy. The LAT (lubrication approximation theory) is employed to simplify the equations. The closed form solution for velocity, temperature, and pressure gradient is obtained. While the pressure and flow rate are obtained numerically. The impact of involved parameters on important physical quantities such as temperature, pressure, and pressure gradient are elaborated through graphs and in tabular form. The pressure and pressure gradient decreases for variation of the couple stress parameter and velocity ratio parameter K. While the variation of the slip parameter increases the pressure and pressure gradient inside the flow geometry. Additionally, flow rate decreases for the variation of the slip parameter as fluid starts moving rapidly along the roller surface. The most important physical quantity which is responsible for maintaining the quality of the coating and thickness is flow rate. For variation of both the couple stress parameter and the slip parameter, the flow rate decreases compared to the Newtonian case, consequently the coating thickness decreases for the variation of the discussed parameter.

scholarly journals Performance Characteristics of a Long Porous Partial Journal Bearing using Couple Stress Fluid

2019 ◽  
Vol 8 (4) ◽  
pp. 4235-4240
Keyword(s):  
Flow Rate ◽  
Couple Stress ◽  
Journal Bearing ◽  
Fluid Model ◽  
Performance Characteristics ◽  
Fluid Film ◽  
Couple Stress Fluid ◽  
Squeeze Film ◽  
Stress Parameter ◽  
Matlab Programming

After effects of studies led on a long porous partial journal bearing for couple stress fluid are thus displayed. Performance characteristics presently determined incorporate the time-height relationship, Fluid film force, Flow rate, frictional force alongside the coefficient of friction. Plan/Technique/Approach -The paper shows a solution for the squeeze film lubrication of a thick, porous, with couple stress fluid model. It is determined that the changed Reynolds condition inferred the fluid film pressures. The modified state of Reynolds equation is analytically solved and closed form expressions are shown for the time-height, the flow rate and friction force with frictional coefficient numerically with the given starting condition using MATLAB programming, the first non-linear equation in the time-height relationship is resolved. The effects on the squeeze film characteristics of couple stresses and permeability are discussed. Findings – It can be seen that the couple stress parameter enhances the bearing characteristics. The bearing performance can be improved with the increase of couple stress parameter ( l  ), eccentricity ratio (ϵ), permeability parameter (ψ). Additional study may be performed using the couple stress fluid model, including the magnetic effect with heat and mass transfer. This model can be used to compare further with other models such as micropolar fluid, rabinowitsch fluid and for comparative study, which models are the most suitable for improving bearing system performance.

scholarly journals Peristaltic Transport of Couple Stress fluids In a Uniform and Non-Uniform Annulus

2016 ◽  
Vol 12 (1) ◽  
pp. 5832-5841
Author(s):  
Abbas Kasaeipoor ◽  
Asha S.K
Keyword(s):  
Pressure Gradient ◽  
Numerical Solution ◽  
Friction Force ◽  
Flow Rate ◽  
Couple Stress ◽  
Outer Tube ◽  
Peristaltic Transport ◽  
Stress Parameter ◽  
Theoretical Results ◽  
Couple Stress Fluids

The aim of the present investigation is to study the peristaltic transport through the gap between coaxial tubes, where the outer tube is non uniform and the inner tube is rigid. The necessary theoretical results such as viscosity, pressure gradient and friction force on the inner and outer tubes have been obtained in terms of couple stress parameter. Out of these theoretical results the numerical solution of pressure gradient, outer friction, inert friction and flow rate are shown graphically for the better understanding of the problem.

scholarly journals Impact of partial slip and lateral walls on peristaltic transport of a couple stress fluid in a rectangular duct

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110136
Author(s):  
Safia Akram ◽  
Najma Saleem ◽  
Mir Yasir Umair ◽  
Sufian Munawar
Keyword(s):  
Couple Stress ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Partial Slip ◽  
Couple Stress Fluid ◽  
Rectangular Duct ◽  
Peristaltic Pumping ◽  
Current Article ◽  
The Impact ◽  
Lateral Walls

The impact of lateral walls and partial slip with different waveforms on peristaltic pumping of couple stress fluid in a rectangular duct with different waveforms has been discussed in the current article. By means of a wave frame of reference the flow is explored travelling away from a fixed frame with velocity c. Peristaltic waves generated on horizontal surface walls of rectangular duct are considered using lubrication technique. Mathematical modelling of couple fluid for three-dimensional flow are first discussed in detail. Lubrication approaches are used to simplify the proposed problem. Exact solutions of pressure gradient, pressure rise, velocity and stream function have been calculated. Numerical and graphical descriptions are displayed to look at the behaviour of diverse emerging parameters.

Unsteady Flow of Couple Stress Fluid Sandwiched Between Newtonian Fluids Through a Channel

2018 ◽  
Vol 73 (7) ◽  
pp. 629-637
Author(s):  
M. Devakar ◽  
Ankush Raje ◽  
Shubham Hande
Keyword(s):  
Unsteady Flow ◽  
Flow Rate ◽  
Couple Stress ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Newtonian Fluids ◽  
Couple Stress Fluid ◽  
Shear Stresses ◽  
Fluid Velocities ◽  
Fluid Parameters

AbstractThe aim of this article is to study the unsteady flow of immiscible couple stress fluid sandwiched between Newtonian fluids through a horizontal channel. The fluids and plates are initially at rest. At an instant of time, a constant pressure gradient is applied along the horizontal direction to generate the flow. The time-dependent partial differential equations are solved numerically using the finite difference method. The continuity of velocities and shear stresses at the fluid-fluid interfaces has been considered. The obtained results are displayed through graphs and are discussed for various fluid parameters pertaining the flow. The volume flow rate is also obtained numerically for diverse fluid parameters and is presented through a table. It is noticed that fluid velocities increased with time and reached a steady state after a certain time level. Also, the presence of couple stresses reduced the fluid velocities. Volume flow rate increased with Reynolds number and is reduced by increase of ratio of viscosities.

scholarly journals Transport of MHD Couple Stress Fluid Through Peristalsis in a Porous Medium Under the Influence of Heat Transfer and Slip Effects

2017 ◽  
Vol 22 (2) ◽  
pp. 403-414 ◽  
Author(s):  
G.C. Sankad ◽  
P.S. Nagathan
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Couple Stress ◽  
Hartmann Number ◽  
Peristaltic Flow ◽  
Couple Stress Fluid ◽  
Brinkman Number ◽  
Slip Effects ◽  
Adaptability Parameters ◽  
The Impact

AbstractAn attempt has been made to examine the effects of magnetohydrodynamic couple stress fluid in peristaltic flow with porous medium under the impact of slip, heat transfer and wall properties. The expressions are obtained for temperature, coefficient of heat transfer and velocity. Influences of different parameters, the Hartmann number, Brinkman number and adaptability parameters on the temperature and warmth trade coefficient are discussed through outlines.

Squeeze film behavior in porous transversely circular stepped plates with a couple stress fluid

2016 ◽  
Vol 33 (2) ◽  
Author(s):  
Santhana Krishnan Narayanan ◽  
A Chamkha ◽  
Sundarammal Kesavan
Keyword(s):  
Surface Roughness ◽  
Couple Stress ◽  
Design Methodology ◽  
Reynolds Equation ◽  
Closed Form Solution ◽  
Stochastic Theory ◽  
Classical Case ◽  
Form Solution ◽  
Couple Stress Fluid ◽  
Squeeze Film

Purpose The purpose of this work is to carry our a study of the effect of surface roughness on squeeze film behavior between two transversely circular stepped plates with couple stress lubricant when the upper circular stepped plate has porous facing which approaches the lower plate with uniform velocity. Design/methodology/approach The modified Stochastic Reynolds equation is derived for Christensen Stochastic theory for the rough surfaces. Closed form solution of the Stochastic Reynolds equation is obtained in terms of Fourier-Bessel series. Findings It is found that the effect of couple stress fluid and surface roughness is more pronounced compared to classical case. Originality/value The problem is original that it consider a couple stress fluid in this type of applications.

Mathematical Analysis of Roll Coating Process by Using Couple Stress Fluid

2019 ◽  
Vol 8 (8) ◽  
pp. 1683-1691 ◽  
Author(s):  
M. Zafar ◽  
M.A. Rana ◽  
M. Zahid ◽  
M.A. Malik ◽  
M.S. Lodhi
Keyword(s):  
Coating Thickness ◽  
Couple Stress ◽  
Flow Parameter ◽  
Couple Stress Fluid ◽  
Lubrication Approximation ◽  
Isothermal Model ◽  
Roll Coating ◽  
Flow Equations ◽  
Pressure Profiles ◽  
Controlling Parameter

In this article, an incompressible isothermal model of a couple stress fluid between two rotating rolls is developed. Lubrication approximation theory is applied to simplify the flow equations. Exact solutions for velocity and pressure profiles are derived. Parameters of an industrial interest like pressure, separating force, coating thickness, detachment point and power transmitted by the rolls to the fluid are computed numerically. It is observed that the flow parameter is a controlling parameter for an exiting coating thickness. As the problem is symmetric, only one half of the geometry is considered.

Coanda Effect on the Impact of Distribution Characteristics of Oil-Air Annular Flow

2014 ◽  
Vol 620 ◽  
pp. 166-170
Author(s):  
Qi Guo Sun ◽  
Dong Xu Chen ◽  
Xiong Shi Wang ◽  
Zheng Hui Zhou
Keyword(s):  
Pressure Gradient ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Annular Flow ◽  
Branch Pipe ◽  
Coanda Effect ◽  
Distribution Characteristics ◽  
Coandǎ Effect ◽  
The Impact

The T-junction model is simulated in Fluent by changing the curvature of branch pipe, and then the distribution characteristics of the annular flow was studied in T-junction distributor. The mass flow and pressure of the annular flow in this T-junction are studied, and the impact of Coanda Effect on the annular flow distribution characteristic is analyzed in oil-air two phases flow. The results show that, Coanda Effect affects the distribution of oil-air annular flow unevenly. The mass flow rate of air phase and the air velocity of outlet increase with decreasing the curvature, while the mass flow rate of liquid decrease with decreasing the curvature of the branch pipe connection; T-shaped junction inlet pressure is high, but the pressure gradient is small, the pressure gradient in the small curvature manifold is larger than that in the large curvature manifold.

Dynamic stability analysis of noncircular two-lobe journal bearings with couple stress lubricant regime

2020 ◽  
pp. 135065012094551
Author(s):  
Mahdi Zare Mehrjardi
Keyword(s):  
Steady State ◽  
Carrying Capacity ◽  
Couple Stress ◽  
Journal Bearings ◽  
Lubricating Oil ◽  
Couple Stress Fluid ◽  
Load Carrying Capacity ◽  
Stress Parameter ◽  
Attitude Angle ◽  
Load Carrying

In this research, the steady state and dynamic performances of two-lobe noncircular journal bearings with couple stress lubricant are presented. The lubricating oil, containing additives and contaminants, is modeled as the couple stress fluid. The modified Reynolds equation is obtained using the couple stress lubrication theory and is then solved by finite element method as an efficient numerical technique. The steady-state characteristics of bearings, including the load carrying capacity and attitude angle, are determined for various values of the couple stress parameter. The results show that applying the couple stress fluid improves the efficiency of two-lobe bearings in terms of an increased load carrying capacity and reduced attitude angle. Also, the stability performance of the investigated bearings is studied using rotor motion equations based on linear and nonlinear dynamic methods. The results indicate that any increase in the lubricant couple stress parameter enhances the bearing ability to damp the rotor perturbations. In other words, by varying the lubricant from Newtonian oil to the couple stress type and upgrading its properties, the curves of the critical mass parameter and whirl frequency ratio have an increasing and decreasing trend, respectively. Based on the fourth-order Runge–Kutta method results, the dynamic trajectory of the rotor center in the bearing space changes with increasing the couple stress parameter from diverging disturbances and limits the cycle perturbations around the bearing center to converging oscillations to the static equilibrium point. Moreover, the effect of changing lubricant properties on the two-lobe bearing’s performance is more pronounced at higher values of the couple stress parameter, especially with an increase in the noncircularity of bearings’ geometry.

Non-isothermal analysis of calendering using couple stress fluid

2017 ◽  
Vol 34 (4) ◽  
pp. 358-381 ◽  
Author(s):  
Nasir Ali ◽  
Muhammad Asif Javed ◽  
Hafiz Muhammad Atif
Keyword(s):  
Pressure Gradient ◽  
Couple Stress ◽  
Sheet Thickness ◽  
Power Input ◽  
Momentum Equation ◽  
Exact Expression ◽  
Couple Stress Fluid ◽  
Flow Equations ◽  
Stress Effects ◽  
Order Of Magnitude

The non-isothermal flow inside a calender is modeled and analyzed for a couple stress fluid. The governing flow equations are developed using conservation laws of mass, momentum and energy. An order of magnitude analysis is performed and leading terms in momentum and energy equations are retained. The reduced momentum equation is solved to obtain the exact expression for velocity and pressure gradient. The reduced energy equation is solved numerically using a hybrid numerical method. The significant effects of the involved parameters on the pressure, pressure gradient velocity profile, roll-separating force, power input, exiting sheet thickness and temperature are examined through various plots. The pressure inside the calender significantly increases with increased couple stress effects. For larger couple stress parameters, the power function and roll-separating function show steady state behavior. The two maxima are distinctly observed in temperature distribution near the roll surfaces for small couple stress effects [Formula: see text]. In contrast, the temperature achieves maximum at center for strong couple stress effects [Formula: see text]

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