scholarly journals Discussion: “Squeeze Film Theory for Micropolar Fluids” (Prakash, J., and Sinha, P., 1976, ASME J. Lubr. Technol., 98, pp. 139–144)

1976 ◽  
Vol 98 (1) ◽  
pp. 144-144
Author(s):  
S. K. Vij
Keyword(s):  
Film Theory ◽  
Squeeze Film ◽  
Micropolar Fluids

Squeeze Film Theory for Micropolar Fluids

1976 ◽  
Vol 98 (1) ◽  
pp. 139-144 ◽  
Author(s):  
J. Prakash ◽  
P. Sinha
Keyword(s):  
Thin Films ◽  
Flow Behavior ◽  
Film Theory ◽  
Continuum Theory ◽  
Squeeze Film ◽  
Micropolar Fluids ◽  
Fluid Theory ◽  
Film Characteristics ◽  
Analytical Expressions ◽  
Circular Disks

Needs’ experimental results on thin films deviate considerably from those predicted by the classical theory when the film thickness is less than 0.00127 mm. In recent years there has been a tendency to attribute this deviation to the inadequacy of the classical continuum theory to describe the fluid flow behavior when confined to narrow passages. In this paper the micropolar fluid theory is applied to the squeeze films for circular disks to explain Needs’ findings. An excellent qualitative agreement is found to exist between the results based on this analysis and Needs’ results. Analytical expressions are obtained for various squeeze film characteristics and effect of microstructure elaborated through graphs.

Stochastic Reynolds equation for the combined effects of piezo-viscous dependency and squeeze-film lubrication of micropolar fluids on rough porous circular stepped plates

2021 ◽  
pp. 135065012110224
Author(s):  
Hanumagowda Bannihalli Naganagowda ◽  
Sreekala Cherkkarathandayan Karappan
Keyword(s):  
Carrying Capacity ◽  
Stochastic Approach ◽  
Squeeze Film ◽  
Closed Form Expression ◽  
Load Carrying Capacity ◽  
Micropolar Fluids ◽  
Pressure Dependent Viscosity ◽  
Load Carrying ◽  
Dependent Viscosity ◽  
Film Characteristics

The aim of this paper is to presents a theoretical analysis on squeeze-film characteristics of a rough porous circular stepped plate in the vicinity of pressure-dependent viscosity and lubrication by micropolar fluids. A closed-form expression for non-dimensional pressure, load, and squeezing time is derived based on Eringen’s theory, Darcy’s equation, and Christensen’s stochastic approach. Results indicate that the effects of pressure-dependent viscosity, surface roughness, and micropolar fluids play an important role in increasing the load-carrying capacity and squeezing time, whereas the presence of porous media decreases the load-carrying capacity and squeezing time of the rough porous circular stepped plates.

A comparison of squeeze-film theory with measurements on a microstructure

1993 ◽  
Vol 36 (1) ◽  
pp. 79-87 ◽  
Author(s):  
M. Andrews ◽  
I. Harris ◽  
G. Turner
Keyword(s):  
Film Theory ◽  
Squeeze Film

Non-Newtonian Micropolar Fluid Squeeze Film Between Conical Plates

2012 ◽  
Vol 67 (6-7) ◽  
pp. 333-337 ◽  
Author(s):  
Jaw-Ren Lin ◽  
Chia-Chuan Kuo ◽  
Won-Hsion Liao ◽  
Ching-Been Yang
Keyword(s):  
Micropolar Fluid ◽  
Reynolds Equation ◽  
Fluid Model ◽  
Load Capacity ◽  
Numerical Results ◽  
Squeeze Film ◽  
Micropolar Fluids ◽  
Newtonian Case ◽  
Film Characteristics ◽  
Film Lubrication

By applying the micropolar fluid model of Eringen (J. Math. Mech. 16, 1 (1966) and Int. J. Mech. Sci. 31, 605 (1993)), the squeeze film lubrication problems between conical plates are extended in the present paper. A non-Newtonian modified Reynolds equation is derived and applied to obtain the solution of squeeze film characteristics. Comparing with the traditional Newtonian case, the non-Newtonian effects of micropolar fluids are found to enhance the load capacity and lengthen the approaching time of conical plates. Some numerical results are also provided in tables for engineer applications

scholarly journals The Performance Effects of Squeeze Film Stiffness on Non-Resonate Interferometric Inertial Sensors

2007 ◽  
Author(s):  
Maximillian A. Perez ◽  
Andrei M. Shkel
Keyword(s):  
Inertial Sensors ◽  
Inertial Sensor ◽  
Film Theory ◽  
Nonlinear Effects ◽  
Squeeze Film ◽  
Nonlinear Frequency ◽  
Reduced Pressure ◽  
Performance Effects ◽  
Film Stiffness ◽  
Kinetic Gas Theory

This paper studies the nonlinear effects of squeeze film stiffening on the performance of a high resolution MEMS nonresonant inertial sensor. It is shown that these effects introduce a surprising dynamic response that extends the operational frequency range of the devices by retarding the resonate response. In addition, this performance advantage will occur without the traditional gain trade-off associated with linear systems of this type. A method is introduced to experimentally characterize the squeeze film stiffness of a passive inertial sensor through the resonant characterization of a Fabry-Pe´rot interferometric accelerometer under reduced pressure. Such passive devices are uniquely suited for the study of squeeze films and, due to the dependence of both the sensitivity and bandwidth on the device structural stiffness, variation of the stiffness with frequency must be considered to accurately predict sensor performance. The characterization confirms established analytical squeeze film stiffness theory in the continuous gas regime for conditions of Knudsen numbers less then one. As the Knudsen number equal to one is approached, it is shown that ideal kinetic gas theory and continuous squeeze film theory converge yielding a simplified stiffness estimate under the resonant response under reduced pressure. These analytical results are used to predict the performance gains due to the nonlinear, frequency dependent total stiffness of the sensor during non-resonant operation.

Numerical Modeling and Simulation of a Condenser Microphone

2010 ◽  
Author(s):  
M. T. Mehrabani ◽  
A. Ranjbar ◽  
F. Torkaman
Keyword(s):  
Dynamic Analysis ◽  
Film Theory ◽  
Measuring Transducer ◽  
Squeeze Film ◽  
Induced Voltage ◽  
The Past ◽  
Condenser Microphone ◽  
Forward Difference ◽  
Cylindrical Coordinate ◽  
Electric Field Force

Non-uniform deflection of a pressure condenser microphone diaphragm causes a nonlinear relationship between the deflection of the diaphragm and the induced voltage. This paper describes how the numerical dynamic analysis carried out with the second order finite difference method in space and forward difference in time domain to determine more accurately this nonlinearity and moreover, to determine the influence of the nonlinear electric field force on the mechanical system of the microphone with respect to time. For this purpose unsteady one dimensional equation of diaphragm vibration has been considered in the cylindrical coordinate. The damping and stiffness coefficients have been calculated using the squeeze film theory. Unlike the past analytical solutions, in this article the dependence of damping coefficient on the number of holes and rings, holes radius and relative angle is studied in detail. The dependence of the microphone capacitance on the diaphragm deflection can be well calculated by solving the Laplace equation using a numerical mapping. The numerical frequency response obtained for a condenser microphone has been compared with analytical solution exists in the literature. The numerical results obtained indicate a very good accuracy of the code. Such a dynamic analysis unlike the past numerical static simulation gives a deeper view into the reasons of the nonlinearity of this important measuring transducer.

Sign in / Sign up

Export Citation Format

Share Document