Range dependence of underwater echo from random rough surfaces

1976 ◽  
Vol 60 (S1) ◽  
pp. S56-S56
Author(s):  
E. E. Mikeska ◽  
C. M. McKinney
Keyword(s):  
Rough Surfaces ◽  
Random Rough Surfaces

scholarly journals A Static Friction Model for Unlubricated Contact of Random Rough Surfaces at Micro/Nano Scale

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 368
Author(s):  
Shengguang Zhu ◽  
Liyong Ni
Keyword(s):  
Rough Surfaces ◽  
Static Friction ◽  
Friction Model ◽  
Elastic Contact ◽  
Nano Scale ◽  
Random Rough Surfaces ◽  
Proposed Model ◽  
Dissipation Mechanism ◽  
Rigid Plane ◽  
Contact Situation

A novel static friction model for the unlubricated contact of random rough surfaces at micro/nano scale is presented. This model is based on the energy dissipation mechanism that states that changes in the potential of the surfaces in contact lead to friction. Furthermore, it employs the statistical theory of two nominally flat rough surfaces in contact, which assumes that the contact between the equivalent rough peaks and the rigid flat plane satisfies the condition of interfacial friction. Additionally, it proposes a statistical coefficient of positional correlation that represents the contact situation between the equivalent rough surface and the rigid plane. Finally, this model is compared with the static friction model established by Kogut and Etsion (KE model). The results of the proposed model agree well with those of the KE model in the fully elastic contact zone. For the calculation of dry static friction of rough surfaces in contact, previous models have mainly been based on classical contact mechanics; however, this model introduces the potential barrier theory and statistics to address this and provides a new way to calculate unlubricated friction for rough surfaces in contact.

Measurement and Prediction of the Effects of Nonuniform Surface Roughness on Turbulent Flow Friction Coefficients

1988 ◽  
Vol 110 (4) ◽  
pp. 380-384 ◽  
Author(s):  
R. P. Taylor ◽  
W. F. Scaggs ◽  
H. W. Coleman
Keyword(s):  
Turbulent Flows ◽  
Rough Surfaces ◽  
Reynolds Numbers ◽  
Base Diameter ◽  
Friction Coefficients ◽  
Friction Factors ◽  
Random Rough Surfaces ◽  
The Status ◽  
Uniform Array ◽  
Prediction Approach

The status of prediction methods for friction coefficients in turbulent flows over nonuniform or random rough surfaces is reviewed. Experimental data for friction factors in fully developed pipe flows with Reynolds numbers between 10,000 and 600,000 are presented for two nonuniform rough surfaces. One surface was roughened with a mixture of cones and hemispheres which had the same height and base diameter and were arranged in a uniform array. The other surface was roughened with a mixture of two sizes of cones and two sizes of hemispheres. These data are compared with predictions made using the previously published discrete element prediction approach of Taylor, Coleman, and Hodge. The agreement between the data and the predictions is excellent.

Distribution of zero crossings for the profile of random rough surfaces

1992 ◽  
Vol 31 (22) ◽  
pp. 4534 ◽  
Author(s):  
Fatima Abdellani ◽  
Georges Rasigni ◽  
Monique Rasigni ◽  
Antoine Llebaria
Keyword(s):  
Rough Surfaces ◽  
Zero Crossings ◽  
Random Rough Surfaces
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