A study on curved circular plates with micropolar fluids

2014

In high pressure fluid flows applications such as fluid film lubrication, microfluidics and geophysics, the piezoviscous effect i.e. viscosity-pressure dependence plays an important role. In the present theoretical investigation, the combined effects of piezo-viscous dependency and non-Newtonian couple stresses on the performance of circular plate squeeze film bearings have been investigated using Stokes Micro-continuum theory of couple stress fluids together with the exponential variation of viscosity with pressure. Analytic solution for film pressure is obtained using small perturbation analysis. The numerical results for pressure and load capacity with different values of viscosity-pressure parameter are calculated and compared with iso-viscous couple stress and Newtonian lubricants. Due to piezo-viscous effect, enhanced pressure, increased load capacity and longer response time is observed in the analysis.

American Journal of Mechanics and Applications, 2019

The present theoretical work investigates the combined impacts of non-Newtonian (pseudoplastic and dilatant) lubricants and surface roughness on the performance of squeeze films lubrication between two rough circular plates. The modified Reynolds equation has been derived on the basis of Christensen's stochastic theory of hydrodynamic lubrication for rough surfaces. The lubricant model adopted for the analysis is Rabinowitsch fluid model-an experimentally verified fluid model for lubricated bearing systems. Two types of one-dimensional roughness patterns (radial and azimuthal) have been considered in the analysis. An asymptotic solution for squeeze film pressure, load carrying capacity and squeeze film time are obtained. The numerical results for dimensionless film pressure, load carrying capacity and film squeezing time have been calculated for various values of fluid and operating parameters. The results for dimensionless film pressure, load capacity and squeezing time of the lubricant film have been discussed with clear graphical presentation for different values of parameters of pseudoplasticity and roughness. It was observed that the radial roughness decreases the film pressure, load capacity and squeezing time of lubricant, while increased values of these properties were observed for azimuthal roughness. It was also observed that the pseudoplastic lubricants decrease the film pressure and load capacity, while the dilatant lubricants increase these properties. Also, the variations in these results are highly significant.

Tribology International, 2014

In this paper, a theoretical analysis on the squeeze film characteristics between circular stepped plates lubricated with Rabinowitsch fluid is presented. By using Rabinowitsch fluid model, the modified Reynolds type equation is derived to study the dilatant and pseudoplastic nature of the fluid in comparison with Newtonian fluid. The closed form solution is obtained by using perturbation method. According to the results obtained, the load-carrying capacity and squeeze film time increases for dilatant fluids as compared to the corresponding Newtonian fluids whereas the reverse trend is observed for pseudoplastic fluids. Further, it is observed that the response time decreases as the step height increases.

Flow Turbulence and Combustion, 1982

In this paper, the lubrication theory for squeezing with micropolar fluids in smooth surfaces has been advanced to analyze the effects arising from roughness considerations using the stochastic approach. This theory is subsequently applied to the problem of squeezing between rough rectangular plates. It is observed that the roughness effects are more pronounced for micropolar fluids as compared to the Newtonian fluids.

Thermal Science

This paper presents the theoretical analysis of comparison of porous structures on the performance of a slider bearing with surface roughness in micropolar fluid film lubrication. The globular sphere model and Irmay's capillary fissures model have been subject to investigations. The general Reynolds equation which incorporates randomized roughness structure with Stokes micropolar fluid is solved with suitable boundary conditions to get the pressure distribution, which is then used to obtain the load carrying capacity. The graphical representations suggest that the globular sphere model scores over the Irmay's capillary fissures model for an overall improved performance. The numerical computations of the results show that, the act of the porous structures on the performance of a slider bearing is improved for the micropolar lubricants as compared to the corresponding Newtonian lubricants.

Indian journal of science and technology, 2022

Objectives: The primary goal of this paper is to study the influence of MHD and micropolar fluid on the squeeze film lubrication between stepped porous parallel plates. Method: The non-Newtonian micropolar fluid MHD Reynolds type equation is derived by considering the flow of micropolar fluid in the porous matrix as described by Darcy's law, as well as microstructure additives and magnetic effects associated with the magnetization of the fluid. The numerical solutions are presented graphically for the MHD squeeze film characteristics for various values of coupling number parameter, characteristic material length, and magnetic Hartmann number. Findings: According to the results, the micropolar fluid and the magnetic effects significantly influence the squeeze film characteristics. Comparing the MHD micropolar fluid impact on the squeeze film lubrication with the corresponding Newtonian and non-magnetic cases, we observe that there is a significant increase in the approaching time and the load-carrying capability. The increase in the step height decreases the squeezing film time. Novelty: The original research was conducted on the magneto-hydrodynamic micropolar fluid squeeze film lubrication between stepped porous parallel plates which has not been studied so far. The effect of applied magnetic field is to enhance the load carrying capacity and delayed time of approach which are the most desirable characteristics for improving the bearing performance.

Journal of Plastic Film & Sheeting, 2018

The theoretical model of roll coating onto a moving sheet is developed based on micropolar fluid constitutive equations and lubrication approximation. Closed form expressions for velocity, microrotation and pressure gradient are obtained. Runge-Kutta method is used to calculate the engineering quantities of interest such as, pressure, roll-separating (load-carrying) force and power input. The separation point is numerically calculated using Newton’s iterative method together with generalized Leibniz rule. The effects of involved parameters on the pressure gradient, velocity, pressure and other mechanical quantities are displayed through various graphs. Extreme pressure is observed in the nip region for larger coupling numbers and microrotation parameters. This leads to increased load-carrying force and power input for micropolar fluid when compared to a Newtonian fluid. Moreover, the separation point decreases from its Newtonian value with increasing [Formula: see text]

The purpose of this paper is to look into the theoretical effects of a ferrofluid lubricated with couple stress fluid on a curved circular plate in the presence of a magnetic field. Using the Shliomis model to account for magnetic particle rotation, their magnetic moments, and the volume concentration in the fluid and Stokes model for couple stress fluid, the modified Reynolds equation is obtained and the results for squeeze film performance is presented. It is observed, the result is more prominent for non-Newtonian ferro fluid as compared to Newtonian non-ferro fluid, also effect volumetric concentration of particles and Langevin parameter enhances the squeeze film characteristics. Further, it is found that the squeeze film pressure, load carrying capacity and response time is more pronounced for concave plate   * 0

European Journal of Mechanics - B/Fluids, 2018

The lubrication theory is mostly concerned with the behavior of a lubricant flowing through a narrow gap. Motivated by the experimental findings from the tribology literature, we take the lubricant to be micropolar fluid and study its behavior in a thin domain with rough boundary. Instead of considering (commonly used) simple zero boundary condition, we impose physically relevant (nonzero) boundary condition for microrotation and perform asymptotic analysis of the corresponding 3D boundary value problem. We formally derive a simplified mathematical model acknowledging the roughness-induced effects and the effects of the nonzero boundary conditions on the macroscopic flow. Using the obtained asymptotic model, we study numerically the influence of the specific rugosity profile on the performance of a linear slider bearing. The numerical results clearly indicate that the use of the rough surfaces may contribute to enhance the mechanical performance of such device.

2018

Load Slip Pressure Micropolar fluid Hydrodynamic In this paper, the modified Reynolds equation of finite slider bearing lubricated with micropolar fluid is numerically solved for the computational aspects of the bearings. The finite difference scheme has been employed to solve the governing equations. The effect of micropolar parameter and slip parameter is investigated on slider bearing. For investigating the effect of slip boundary on the pressure distribution in sliding surface is numerically presented in the Reynolds model. The two-dimensional modified Reynolds equation can predict the performance of lubrication process with boundary slip in sliding contact which can be seen by the obtained results. The pressure and load capacity are displayed graphically. The pressure and load carrying capacity is lesser for slip case as compared to no slip case.