The Navier-Stokes and compressible Reynolds equations are solved for gas lubricated textured parallel slider bearings under hydrodynamic lubrication for a range of realistic texture geometry parameters and operating conditions. The simplifying assumptions inherent in the Reynolds equation are validated by comparing simulation results to the solution of the Navier-Stokes equations. Using the Reynolds equation to describe shear driven gas flow in textured parallel slider bearings is justified for the range of parameters considered.

The Rayleigh step bearing is considered in one dimensional geometry. It is a well established fact that the roughness has a significant effect on the performance of the hydrodynamic lubrication of a slider bearing. An attempt has been made to study and analyze the effect of transverse roughness in the presence of a magnetic fluid for a Rayleigh step bearing. The bearing surfaces are assumed to be transversely rough. The roughness of the surfaces has been characterized by a random variable with non-zero mean, variance and skewness. The stochastically averaged Reynolds equation is solved with suitable boundary conditions to obtain the pressure distribution in turn, which is used to get the load carrying capacity. The results presented in graphical form indicate that the effect of transverse roughness is significantly adverse. However, this article establishes that there exist sufficient scopes for improving the performance of the bearing system in the case of negatively skewed roughness especially, when negative variance is involved, in spite of the fact that the standard deviation introduces a negative effect. Besides, the performance of the bearing system improves significantly owing to the presence of the magnetic fluid lubricant. The adverse effect of roughness can be minimized by the positive effect of magnetization at least in the case of negatively skewed roughness. Therefore, this investigation offers some measures even from bearing’s life period point of view.

The tribological performance of different microtexture shapes is evaluated for the case of gas lubricated textured parallel slider bearings. The geometry of each shape is optimized in terms of load carrying capacity, after which the performance of different shapes is compared relative to each other. The ellipsoidal shape is found to generate the largest load carrying capacity.

The combined effects of surface roughness and lubricant rheology on the performance characteristics of a hydrodynamic inclined slider bearing are investigated by means of the homogenized method. The pad surface is rough and stationary while the lower surface is assumed to be smooth and moving. The V. K. Stokes couple stress fluid model is adopted to describe the rheological behavior of the lubricant flowing between the two surfaces. The numerical simulations are performed by considering three roughness patterns (transverse, longitudinal and anisotropic), and various values of the couple stress parameter. It is found that the homogenization method is rigorous and efficient for the three roughness patterns considered. It is also found that the combined effects of the surface roughness as well as the couple stress due to the presence of polymer additives on the hydrodynamic performance characteristics such as load carrying capacity, friction factor are significant.

This study focuses on the thermohydrodynamic lubrication analysis of fluid film bearings with step on the surface such as a Rayleigh step bearing. In general, the Reynolds equation does not satisfy the continuity of the fluid velocity components at steps. This discontinuity results in the difficulty to solve the energy equation for the lubricants, because the energy equation needs the velocity components explicitly. The author has solved this problem by introducing the equivalent clearance height and the equivalent gradient of clearance height at steps. These parameters remove the discontinuity of velocity components and the energy equation as well, so that one can solve these equations on all of the bearing surfaces including the step region by finite differential method (FDM). The numerical results of pressure and temperature distributions by the proposed method for a Rayleigh step bearing were compared with the results obtained by a commercial CFD package. These results showed good agreement with each other. This method is extended to 2D unequal grid problems.

There has recently been much interest in the micro-texturing of slider bearings, where many tiny micro-pockets are incorporated into one of the bearing surfaces. Proponents of this technology have reported that the application of micro-texture to sliding bearing surfaces can result in up to 40% reduction in friction, when the two bearing surfaces have low or zero convergence ratio, i.e. are near parallel [1]. The authors have shown previously, through a series of one dimensional analyses, that the ability of such bearings to generate load support can be explained by a lubrication mechanism termed “Inlet Suction” [2, 3]. In the current paper, these one dimensional analyses are extended to two dimensions with the inclusion of a mass-conserving cavitation algorithm based on Elrod [4]. This allows for a more complete understanding of “Inlet Suction” in real bearing geometries.

This paper analyses the thermal and roughness effects on different characteristics of an infinitely long tilted pad slider bearing considering heat conduction through both the pad and slider. The roughness is assumed to be stochastic, Gaussian randomly distributed. Density and viscosity are assumed to be temperature dependent. The irregular domain of the fluid due to roughness is mapped to a regular domain so that the numerical method can be easily applied. The modified Reynolds equation, momentum equation, continuity equation, energy equation and the heat conduction equations on the pad and slider are coupled and solved using finite difference method to yield various bearing characteristics. The solutions with respect to different pad and slider boundary conditions are elaborated through tables and figures.

This work is a thermal simulation extension to the modeling of the fluid flow inside a reservoir-extended porous slider bearing [1]. The bearing system consists of a lubricating film, porous medium, and a reservoir. The velocity flow field generated by the modeling of the fluid flow is used as an input to solve the heat transfer problem. The small parameter used in the asymptotic expansion is the ratio of the reservoir depth to the length of the slider. The thermal effects upon the operation of this system are discussed.

Surface texturing has been shown to have friction reducing / load capacity increasing effects in parallel sliders, as well as in cylinder-liner contacts and in hydrodynamic seals. However, if texture is to be regarded as the sole mean of hydrodynamic lift in parallel sliders, or as a way of improving hydrodynamic performance in slider, thrust and journal bearings, several issues have to be addressed, such as optimal texturing parameters and corresponding performance gains. This paper deals with these issues in the case of a plane inclined textured slider. Parametric studies are conducted to determine optimal texturing extents, dimple depth and texturing density, as well as the influence of the operating conditions on these optimal texturing parameters.

This work considers a porous slider bearing above an external reservoir. The bearing system consists of a lubricating film, porous medium, and a reservoir. The Darcy model is used for flow inside the porous medium. The moving slider bearing establishes a pressure profile that circulates fluid between the lubricating region and the reservoir. Simplifications are made to allow for a semi-analytical solution to be constructed that can be easily solved using a standard computational package. It is shown that the fluid is circulated inside the bearing to allow for a load-carrying capability as well as for no external lubricant supply.

The film height distribution which yields the maximum load carrying capacity for the rectangular slider is determined using a PDE-constrained optimization solver. The gradient of the objective function, i.e. the load, with respect to the design variable, i.e. the film height distribution, is calculated using a discrete adjoint approach. It is shown that, in contrast to the linear slider, the load carrying capacity per unit length and at constant width of the optimized slider steadily increases with increasing length over width ratio.

The direct simulation Monte Carlo method (DSMC) is used to study rarefied gas flow between an inclined plane slider bearing and a nano channel representing one groove in a discrete track recording head/disk interface. The forces acting on the slider are investigated as a function of slider pitch angle, disk velocity, track pitch, groove width, and groove depth. The influence of the absolute groove size on the slider forces is found to be small.

A new method for the optimization of slider bearings in magnetic recording disk drives is described. The new approach subdivides the chosen design area of the slider to be optimized in a number of small rectangular subregions. Each subregion is allowed to be at one of two height levels, one level corresponding to the air bearing surface and the other to the intermediate level between recess level and air bearing level. The pressure distribution over the slider and the flying height of the slider are calculated for all possible combinations of height levels of the subregions and the solution is determined that minimizes a chosen objective function. After determining an optimum solution with an initial coarse subdivision, a refinement of the solution is obtained by further subdivision of the individual subregions, and repeating the evaluation of the objective function to determine the optimum solution. The subregion approach does not require an a priory knowledge of a good initial design and results in novel air bearing contours.