Slow motion of a sphere away from a wall: Effect of surface roughness on the viscous force

2002 ◽  
Vol 112 (4) ◽  
pp. 641-654 ◽  
Author(s):  
Sunil Datta ◽  
Manju Shukla
Keyword(s):  
Surface Roughness ◽  
Slow Motion ◽  
Wall Effect ◽  
Viscous Force ◽  
Effect Of Surface

Investigation on Effect of Surface Roughness Pattern to Drag Force Reduction Using Rotary Rheometer

2005 ◽  
Vol 128 (1) ◽  
pp. 131-138 ◽  
Author(s):  
Chen Haosheng ◽  
Chen Darong ◽  
Li Yongjian
Keyword(s):  
Surface Roughness ◽  
Drag Force ◽  
Smooth Surface ◽  
Side Wall ◽  
Viscous Force ◽  
Longitudinal Groove ◽  
Pressure Drag ◽  
Side Walls ◽  
Force Reduction ◽  
Effect Of Surface

A drag force reduction experiment is performed on polyoxyethylene (PEO) water solution using a rotary rheometer. Longitudinal, transverse, and isotropic grooves are notched on the rotor’s surface to investigate the effect of surface roughness patterns. The experiment results show that higher drag force is generated on the surface with transverse grooves compared with the drag force on a smooth surface, while lower drag force is generated on the surface with longitudinal grooves. The drag force on the surface with isotropic grooves is between them. Forces on the side wall of the grooves play important roles in drag force reduction. They are numerically analyzed based on the Navier-Stokes equation using the finite volume method. The viscous force on the groove’s bottom plane is far less than the force on the corresponding plane of the smooth surface, but the drag force on the groove’s surface is compensated either by the pressure drag on the side walls of the transverse groove or by the viscous force on the side walls of the longitudinal groove. The pressure drag on side wall of transverse groove is always higher than the viscous force on side wall of longitudinal groove. The numerical results cope with the experiment results that only the surface with longitudinal grooves can reduce the drag force.

The effect of surface roughness on AES depth profile.

Shinku ◽  
1987 ◽  
Vol 30 (10) ◽  
pp. 793-798 ◽  
Author(s):  
Masao HIRASAKA ◽  
Masao HASHIBA ◽  
Toshiroh YAMASHINA
Keyword(s):  
Surface Roughness ◽  
Depth Profile ◽  
Effect Of Surface

Effect of surface sealant on surface roughness and bacterial adhesion of bulk-fill composites

2021 ◽  
pp. 096739112110055
Author(s):  
Gunce Ozan ◽  
Meltem Mert Eren ◽  
Cansu Vatansever ◽  
Ugur Erdemir
Keyword(s):  
Surface Roughness ◽  
Bacterial Adhesion ◽  
Confocal Laser ◽  
High Caries Risk ◽  
Two Samples ◽  
Significant Difference ◽  
Restorative Materials ◽  
Surface Sealants ◽  
Surface Sealant ◽  
Effect Of Surface

Surface sealants are reported to ensure surface smoothness and improve the surface quality of composite restorations. These sealants should also reduce the bacterial adhesion on composite surfaces however, there is not much information regarding their performance on bulk-fill composite materials. The aim of this study was to evaluate the effect of surface sealant application on surface roughness and bacterial adhesion of various restorative materials. Disc-shaped samples were prepared from a compomer, a conventional composite and three bulk-fill composites. Specimens of each group were divided into two groups (n = 9): with/without surface sealant (Biscover LV, [BLV]). Surface roughness values were examined by profilometry and two samples of each group were examined for bacterial adhesion on a confocal laser scanning microscope (CLSM). Bacterial counts were calculated by both broth cultivation and microscopic images. Results were analyzed with one-way ANOVA and Bonferroni/Dunn tests. Following the BLV application, there was a decrease in the surface roughness values of all groups however, only Tetric N-Ceram Bulk and Beautifil-Bulk groups showed significantly smoother surfaces (p < 0.001). There were no significant differences among material groups without BLV application. Evaluating bacterial adhesion after BLV application, conventional composite had the lowest values among all followed by the compomer group. Beautifil-Bulk had significantly the highest bacterial adhesion (p < 0.05), followed by Tetric N-Ceram Bulk group. Without BLV application, there was no significant difference among bacterial adhesion values of groups (p > 0.05). CLSM images showed cell viability in groups. Bulk-fill composites showed higher bacterial adhesion than conventional composite and compomer materials. The surface sealant was found to be highly effective in lowering bacterial adhesion, but not so superior in smoothing the surfaces of restorative materials. So, surface sealants could be used on the restorations of patients with high caries risk.

Effect of surface roughness on couple stress squeeze film lubrication of long porous partial journal bearings

2006 ◽  
Vol 58 (4) ◽  
pp. 176-186 ◽  
Author(s):  
N.M. Bujurke ◽  
N.B. Naduvinamani ◽  
Syeda Tasneem Fathima ◽  
S.S. Benchalli
Keyword(s):  
Surface Roughness ◽  
Couple Stress ◽  
Journal Bearings ◽  
Squeeze Film ◽  
Film Lubrication ◽  
Effect Of Surface

Effect of Surface Roughness on Pool Boiling Heat Transfer of Water on a Superhydrophilic Aluminum Surface

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Jinsub Kim ◽  
Seongchul Jun ◽  
Jungho Lee ◽  
Juan Godinez ◽  
Seung M. You
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Boiling Heat Transfer ◽  
Aluminum Surface ◽  
Transfer Coefficients ◽  
Copper Surfaces ◽  
Heat Transfer Coefficients ◽  
Superhydrophilic Surface ◽  
Aluminum Surfaces ◽  
Effect Of Surface

The effect of surface roughness on the pool boiling heat transfer of water was investigated on superhydrophilic aluminum surfaces. The formation of nanoscale protrusions on the aluminum surface was confirmed after immersing it in boiling water, which modified surface wettability to form a superhydrophilic surface. The effect of surface roughness was examined at different average roughness (Ra) values ranging from 0.11 to 2.93 μm. The boiling heat transfer coefficients increased with an increase in roughness owing to the increased number of cavities. However, the superhydrophilic aluminum surfaces exhibited degradation of the heat transfer coefficients when compared with copper surfaces owing to the flooding of promising cavities. The superhydrophilic aluminum surfaces exhibited a higher critical heat flux (CHF) than the copper surfaces. The CHF was 1650 kW/m2 for Ra = 0.11 μm, and it increased to 2150 kW/m2 for Ra = 0.35 μm. Surface roughness is considered to affect CHF as it improves the capillary wicking on the superhydrophilic surface. However, further increase in surface roughness above 0.35 μm did not augment the CHF, even at Ra = 2.93 μm. This upper limit of the CHF appears to result from the hydrodynamic limit on the superhydrophilic surface, because the roughest surface with Ra = 2.93 μm still showed a faster liquid spreading speed.

Effect of Surface Roughness on Slip Resistance of Rubber

2011 ◽  
Vol 189-193 ◽  
pp. 1538-1542
Author(s):  
Li Xiao Jia ◽  
Yong Zhen Zhang ◽  
Yong Ping Niu ◽  
San Ming Du ◽  
Jian Li
Keyword(s):  
Surface Roughness ◽  
Correlation Coefficient ◽  
Correlation Coefficients ◽  
Roughness Parameters ◽  
Test Conditions ◽  
Slip Resistance ◽  
Materials Used ◽  
Almost All ◽  
Effect Of Surface

In order to decrease accidents of slips and falls, COFs of rubber samples with different surface roughness were measured by Brungraber Mark II. And the correlation coefficients between roughness parameters and COF were calculated. The rusults have shown that the COF increases with surface roughness and the correlation coefficient between Sq and COF is highest. In general, almost all the roughness parameters used in the study have high correlation with COF. Parameters had the highest correlation with COF depends on the materials used and test conditions.

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