Papers by Keyword: Control Volume Method

Abstract: Solidification and cooling processes proceeding in the metal domain can be described in different ways. One of them consists in the application of the Fourier-type equation in which the additional term (source function) controlling the solidification process is introduced. In this paper this type of energy equation is used, but for the phase change modeling the equation discussed is in some way transformed. Such a modification is possible if one considers the pure metal for which the solidification point is a constant value. The numerical model used at the stage of computations is based on the Control Volume Method. In the final part of the paper, examples of computations are shown.

Abstract: This paper presents the evaluation of residual stresses and stresses induced by external loads in a water drinker by numerical and experimental methods. The part, used in animal husbandry, is made of grey cast iron (EN GJL 200). Numerical simulations were based on the finite element method, using ANSYS Workbench software to determine the stresses produced by external loads and finite volume method, using NovaFlow software, to determine residual stresses. The results obtained by numerical methods, were validated by experimental methods. Applied experimental methods consist of electrical resistive strain gauge technique to determine the state of stress in various loading conditions and the blind hole method to determine residual stresses, respectively.

Abstract: The drying of porous media is studied in this paper by means of the continuous approach and the control volume method. Both transport phenomena inside the porous medium and overall drying kinetics are analyzed. The model utilized in this study requires a lot of physical properties. All of them have been established experimentally. The capillary pressure, which depends on the moisture content, is obtained by a mercury intrusion curve.

Abstract: In order to protect the slider and disk from excessive wear, a numerical scheme is proposed for transient dynamics at slider/disk interface with the emphasis on the slider wear mechanism and the surface topology optimization of sub-ambient pressure slider. For each transient flying height and slider attitude, the modified Reynolds lubrication equation is solved by the control volume method to obtain the simultaneous pressure distribution in the slider surface. Then the dynamic flying attitude of the slider subject to the calculated pressure distribution can be solved by the Quasi-Newton iteration method at each time step. On the basis of above work, the optimization of the slider surface topology is implemented, and it’s concluded that slider crown has the most significant impact on the dynamic flying attitude and stability. Finally, a sub-ambient pressure slider is designed, which can effectively avoid the slider wear and severe fault of hard disk drive.

Abstract: The objective of the literature is to investigate the influence of micro-arc grooves on the surfaces of the sliding tribopairs by plain pads to hydrodynamic lubrication. This is accomplished by the CFD-approach (computational fluid dynamic approach) where the momentum and continuity equations are solved separately, laminar model and SIMPLE algorithm in theory of Control Volume Method are adopted, and the rheology is assumed to be Newtonian. For various widths and depths of micro arc-grooves, the load supporting capacity of oil-film is calculated in the form of a net total force and static pressure, the friction is compared by the stress of smooth wall, and the dynamical pressure of the upper walls is shown. It will be found that width has more influences than depths to hydrodynamic lubrication, and relative parameters change monotonously with the depth of arc groove. Moreover, given primary film thickness as 6μm, within physically reasonable range of the parameters (depth and width of groove), i.e. in addition to w=40μm, hp=5μm~15μm, the effect of texturing arc-grooves on improvement of tribological properties will be conspicuous.

Abstract: The effect of various micro isosceles-trapezoid grooves on improvement of tribological performance is discussed. It is accomplished through the CFD-approach where the momentum and continuity equations are solved separately, one of low Reynolds turbulence models-Abid index and SIMPLE algorithm in theory of Control Volume Method are adopted. For different width and depth of micro isosceles-trapezoid grooves, the load supporting capacity of oil-film are compared. The results show that the widths has more influence than the depths on hydrodynamic lubrication, and relative parameters change monotonously with the depth of micro-groove. The effect of texturing arc-grooves on improvement of tribological properties is conspicuous if w₁ = 40μm, w₂ = 10μm and h_p = 10μm for micro isosceles-trapezoid grooves.

Abstract: A continuum model of the evolution of air ingestion and entrainment for open-ended squeeze film dampers is proposed in this paper. Hydrodynamic lubrication theory is extended to lubrication with mixture of a Newtonian liquid and an ideal gas. The solution to the universal Reynolds equation is determined numerically using a control volume method (Elrod algorithm) and the forth-order Range-Kutta method. This method conserves mass throughout the computational domain including air ingestion and entrainment. Excellent agreement is found with the experimental works of Diaz and San Andrès for the squeeze film damper [1, 2].