Influence of Micro Trapezoidal-Groove on Behavior of Sliding Tribopairs

2010 ◽  
Vol 37-38 ◽  
pp. 544-549 ◽  
Author(s):  
Pei Yun Zhang ◽  
Yan Hu Zhang ◽  
Xiao Li Wang ◽  
Xi Jun Hua ◽  
Yong Hong Fu
Keyword(s):  
Hydrodynamic Lubrication ◽  
Control Volume ◽  
Turbulence Models ◽  
Simple Algorithm ◽  
Tribological Performance ◽  
Control Volume Method ◽  
Supporting Capacity ◽  
Continuity Equations ◽  
Isosceles Trapezoid ◽  
Volume Method

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 hp= 10μm for micro isosceles-trapezoid grooves.

2D CFD Analysis of Micro Arc-Groove on the Surface of Tribopairs

2011 ◽  
Vol 464 ◽  
pp. 614-618
Author(s):  
Pei Yun Zhang ◽  
Yan Hu Zhang ◽  
Xi Jun Hua ◽  
X.K. Liu ◽  
Bi Feng Yin ◽  
...  
Keyword(s):  
Static Pressure ◽  
Hydrodynamic Lubrication ◽  
Control Volume ◽  
Fluid Dynamic ◽  
Simple Algorithm ◽  
Total Force ◽  
Dynamic Approach ◽  
Continuity Equations ◽  
Reasonable Range ◽  
Volume Method

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.

Turbulent Flow and Heat Transfer in a Porous Chamber

2003 ◽  
Author(s):  
Marcelo Assato ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Turbulent Flow ◽  
Control Volume ◽  
Numerical Technique ◽  
Turbulence Models ◽  
Simple Algorithm ◽  
Macroscopic Models ◽  
Flow And Heat Transfer ◽  
Non Linear ◽  
Porosity And Permeability ◽  
Volume Method

This work presents a numerical investigation of turbulent flow past a porous structure in a channel using linear and non-linear eddy viscosity macroscopic models. Parameters such as porosity and permeability of the porous material are varied in order to analyze their effects on the flow pattern, particularly on the damping of the recirculating bubble after the entrance and exit regions. The numerical technique employed for discretizing the governing equations is the control-volume method. The SIMPLE algorithm is used to correct the pressure field. The classical wall function is utilized in order to handle flow calculation near the wall. A discussion on the use of this technique for simulating the flow in question is presented. Comparisons of results simulated with both linear and non-linear turbulence models are shown.

A New Implicit Numerical Treatment for Non-Linear Turbulence Models and Its Application to Channels With Spatially Periodic Corrugated Walls

2002 ◽  
Author(s):  
Marcelo Assato ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Control Volume ◽  
Turbulence Models ◽  
Simple Algorithm ◽  
Numerical Treatment ◽  
Linear Diffusion ◽  
Viscosity Models ◽  
Non Linear ◽  
Diverging Channel ◽  
Spatially Periodic ◽  
Volume Method

This work examines the performance of linear and nonlinear eddy-viscosity models when used to predict the turbulent flow in periodically sinusoidal-wave channels. Two geometries are investigated, namely a converging-diverging channel and a channel with concave-convex walls. The numerical method employed for the discretization of the equations is the control-volume method in a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm is used for correcting the pressure field. The classical wall function and a low Reynolds model are used to describe the flow near the wall. Comparisons between those two approaches using linear and non-linear turbulence models are done. Here, an implicit numerical treatment was proposed for the non-linear diffusion terms of the momentum equations in order to increase the robustness of the solution method.

Effect of Thermal Conductivity Ratio on Laminar Double-Diffusive Free Convection in a Porous Cavity

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Paulo H. S. Carvalho ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Free Convection ◽  
Thermal Equilibrium ◽  
Control Volume ◽  
Simple Algorithm ◽  
Thermal Conductivity Ratio ◽  
Control Volume Method ◽  
Algebraic Equations ◽  
Square Cavity ◽  
Volume Method ◽  
Double Diffusive

This work presents a study on double-diffusive free convection in a porous square cavity using the thermal equilibrium model. Transport equations are discretized using the control-volume method, and the system of algebraic equations is relaxed via the SIMPLE algorithm. The effect of ks/kf on average Nusselt and Sherwood values was investigated. Results show that increasing ks/kf affects Nuw and Shw boosting mass transfer at the expense of reducing overall heat transport across the enclosure.

The Structure of Turbulence in a Moving Bed as a Function of Flow and Medium Properties

2014 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Reynolds Number ◽  
Turbulent Flows ◽  
Control Volume ◽  
Mechanical Energy ◽  
Simple Algorithm ◽  
Darcy Number ◽  
Control Volume Method ◽  
Governing Equations ◽  
Bed Porosity ◽  
Volume Method

This article presents simulations for turbulent flows in a moving permeable bed making use of a macroscopic turbulence model. Intra-pore turbulence is considered by means of a two-equation closure. Governing equations for mean and turbulent flows are volume-averaged. The resulting set of transport equations is discretized using the control-volume method and the obtained algebraic equation set is relaxed via the SIMPLE algorithm. Results indicate that for larger values of Reynolds number, a greater amount of available mechanical energy is converted into turbulence. Simulations further indicate that for lower values of Darcy number and bed porosity, higher levels of turbulence kinetic energy are calculated.

scholarly journals A New Formulation of Maxwell’s Equations

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 868
Author(s):  
Simona Fialová ◽  
František Pochylý
Keyword(s):  
Numerical Methods ◽  
Maxwell’S Equations ◽  
Maxwell's Equations ◽  
Control Volume ◽  
Control Volume Method ◽  
Integral Forms ◽  
New Formulation ◽  
Electrical Induction ◽  
Volume Method ◽  
Integral Identities

In this paper, new forms of Maxwell’s equations in vector and scalar variants are presented. The new forms are based on the use of Gauss’s theorem for magnetic induction and electrical induction. The equations are formulated in both differential and integral forms. In particular, the new forms of the equations relate to the non-stationary expressions and their integral identities. The indicated methodology enables a thorough analysis of non-stationary boundary conditions on the behavior of electromagnetic fields in multiple continuous regions. It can be used both for qualitative analysis and in numerical methods (control volume method) and optimization. The last Section introduces an application to equations of magnetic fluid in both differential and integral forms.

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