Scientists examine the flow of liquid at the contact between randomly rough surfaces

Oct 19, 2011

A team of scientists from Italy and Germany has recently developed a model to predict the friction occurring when a rough surface in wet conditions (such as a road on a rainy day) is in sliding contact with a rubber material (such as a car tire tread block) in an article to be published shortly in the European Physical Journal E.

In their study, B.N.J. Persson from the Jülich Research Center in Germany and M. Scaraggi from the Polytechnic of Bari in Italy examined the flow of liquid at the contact between randomly rough surfaces. The contact interface looks like a labyrinth with vertically narrow void channels intersecting randomly. This causes channels to be either filled with water or not when in .

For the first time, the authors applied a statistical analytical method to determine the average fluid flow at the interface of rough surfaces. Understanding this flow is important because it is inherently linked to the phenomenon of at the contact between the two surfaces.

Previous attempts to understand friction in such conditions used numerical approaches that required large computing power. They were based on calculating real roughness contacts by singling out each individual portion of the overall rough surface under study. Often, heavy approximations in the description of the simulated surface were applied to decrease the computational time.

The model presented in this paper provides theoretical predictions of friction as a function of the surface sliding velocity. It confirms previous experimental friction measurements made with a smooth steel ball sliding on a rough rubbery surface patterned with parallel grooves. The authors' model confirmed the experimental observation of a changing friction level related to a change in the angle between the direction of movement of the ball and the parallel to the grooves.

Potential applications would require that such a model be used to help create surfaces, such as microstructured tyres, which do not lower their grip when it rains.

Explore further: Controlling core switching in Pac-man disks

More information: Persson BNJ, Scaraggi M (2011). Lubricated sliding dynamics: flow factors and Stribeck curve. European Physical Journal E. 34: 113, DOI 10.1140/epje/i2011-11113-9

add to favorites email to friend print save as pdf

Related Stories

Fingerprints do not improve grip friction

Jun 12, 2009

Fingerprints mark us out as individuals and leave telltale signs of our presence on every object that we touch, but what are fingerprints really for? According to Roland Ennos, from the University of Manchester, ...

'Heftier' atoms reduce friction at the nanoscale

Nov 01, 2007

A research team led by a University of Pennsylvania mechanical engineer has discovered that friction between two sliding bodies can be reduced at the molecular, or nanoscale, level by changing the mass of the atoms at the ...

Shaking Reduces Friction

Jul 08, 2005

Lateral vibrations can control friction at the nanoscale, researchers reported in the 1 July 2005 issue of Physical Review Letters.

Recommended for you

Controlling core switching in Pac-man disks

14 hours ago

Magnetic vortices in thin films can encode information in the perpendicular magnetization pointing up or down relative to the vortex core. These binary states could be useful for non-volatile data storage ...

Atoms queue up for quantum computer networks

14 hours ago

In order to develop future quantum computer networks, it is necessary to hold a known number of atoms and read them without them disappearing. To do this, researchers from the Niels Bohr Institute have developed ...

New video supports radiation dosimetry audits

Dec 23, 2014

The National Physical Laboratory (NPL), working with the National Radiotherapy Trials Quality Assurance Group, has produced a video guide to support physicists participating in radiation dosimetry audits.

Acoustic tweezers manipulate cell-to-cell contact

Dec 22, 2014

Sound waves can precisely position groups of cells for study without the danger of changing or damaging the cells, according to a team of Penn State researchers who are using surface acoustic waves to manipulate ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.