Multiple-relaxation-time lattice Boltzmann method of hydrodynamic lubrication in lemon-bore bearing

Author(s):  
Alireza Arab Solghar

The lattice Boltzmann method has superiority over conventional computational fluid dynamics methods, particularly for the flow simulations in complex geometries. In the present work, the performance of hydrodynamic lemon-bore (elliptical) journal bearings was investigated with the implementation of the lattice Boltzmann method. The steady-state laminar flow of a homogeneous oil was considered in the computations. A linear interpolation method was exploited to obtain the surface curvatures. The comparison of the results obtained from the proposed methodology with available literature data showed a satisfactory agreement. The effect of geometrical parameters on the hydrodynamic lubrication in an elliptical journal bearing was analyzed. It was found that the ellipticity ratio has profound effects on the bearing load capacity, oil flow rate and bearing power loss.

Author(s):  
Chunxiao Jiao ◽  
Zijun Leng ◽  
Donglin Zou ◽  
Na Ta ◽  
Zhushi Rao

A new computational fluid dynamics method, the incompressible lattice Boltzmann method (LBM) is utilized to simulate fluid flow of the infinitely wide wedge in this paper. Compared with the traditional method, LBM is a mesoscopic scale method and some characteristics can be described more clearly with LBM. In this article, three kinds of model .i.e. linear type, parabolic type and harmonic type wedge models are built. The streamline and velocity contour in the fluid field are described. The pressure distribution of different types wedge is studied in LBM. The results manifest that, for the same bottom boundary velocity, the parabolic type and harmonic type wedges are easy to form a vortex, and the load capacity in the harmonic type wedge model is the largest. This paper is ready to investigate the microscopic lubrication mechanism of journal bearing in the future.


2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Kaushik Mondal ◽  
Anandaroop Bhattacharya

Abstract This paper reports our numerical studies on pool boiling heat transfer from a plane and with protruding surface using single component pseudo-potential phase change model of lattice Boltzmann method. The surface protrusions are assumed to be rectangular in shape with a given height and width. The surface protrusions are seen to promote nucleation of bubbles from the heated surface resulting in significantly higher heat transfer rates compared to the plane surface. Spatial and temporal averaged heat fluxes from all these protruding surfaces are found to be 3–4 times higher than that of a plane surface. The effects of the protrusion height, width, spacing, and associated geometrical parameters on surface heat flux have been investigated in order to arrive at an optimal design for maximum heat transfer.


Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 896
Author(s):  
Dian-Ji Lin ◽  
Ling-Zhe Zhang ◽  
Meng-Chao Yi ◽  
Xin Wang ◽  
Shu-Rong Gao ◽  
...  

The contact time of droplets on superhydrophobic surfaces is an especially important parameter in many applications, such as self-cleaning, anti-icing, and spray cooling. In this study, we investigate the contact time of two identical droplets simultaneously impacting superhydrophobic surfaces decorated with three different macrotextures, i.e., bathtub-like groove (S1), vertical wall (S2), and rectangular ridge (S3), via lattice Boltzmann method (LBM) simulations. We explore influences of the geometrical parameters of the macrotextures, as well as the center-to-center distance of the two droplets, on the contact time. We found a new rebounding regime with significantly reduced contact times. We demonstrate that, as compared with impacting a smooth superhydrophobic surface, the contact time can be decreased by 41% for macrotexture S1 because of the asymmetric spreading and retraction of droplets motivated by the macrotexture. We also demonstrate that the new regime depends on the center-to-center distance and geometrical parameters of the macrotextures.


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