Aim of this study is to evaluate a new three-equation turbulence model applied to flow and heat transfer through a pipe. Uncertainty is approximated by comparing with published direct numerical simulation results for fully-developed flow. Error in the mean axial velocity, temperature, friction, and heat transfer is found to be negligible. Keywords—Heat Transfer, Nusselt number, Skin friction, T...

* Current address – Department of Industrial Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI 53201 † Corresponding author – [email protected] Tel: +91-80-22932301 Fax: +91-80-23600648 ABSTRACT Surface texture influences friction and transfer layer formation during sliding. In the present investigation, three well-defined surface textures namely unidirectional, 8-ground, ...

We studied the ability of surfactants to reduce friction by boundary lubrication for a bulk hydrogel sliding on a solid surface in an aqueous solution. A piece of negatively charged polyelectrolyte hydrogel was slid across solid surfaces with various levels of hydrophobicity, using a strain-controlled parallel-plate rheometer in water. A dramatic reduction in the sliding friction, especially in...

Quasistatic mechanical systems are those in which mass or acceleration are sufficientlysmall that the inertial term mu in F = mu is negligible compared to dissipative forces. In roboticsquasistatic mechanics may be used for systems with friction when motions are sufficiently slow. Here weconsider a general quasistatic system with constraints and both dissipative and conservative for...

We derive an effective boundary condition for dense granular flow taking into account the effect of the heterogeneity of the force network on sliding friction dynamics. This yields an intermediate boundary condition which lies in the limit between no slip and Coulomb friction; two simple functions relating wall stress, velocity, and velocity variance are found from numerical simulations. Moreov...

This paper addresses the coefficient of kinetic friction of relatively warm ice (-50 °C) sliding slowly (<1 m s) over itself and presents physical models to account for two characteristics: velocity-strengthening at lower speeds and velocity-weakening at higher speeds. The models are based upon a combination of creep deformation within a near-surface zone and frictional heating cum localized me...

We present results from molecular dynamics simulations of a sphere moving down an inclined plane made rough by glueing other spheres to it. The moving sphere experiences an eeective friction force due to collisions with the balls on the plane, and can maintain a steady state with a constant mean velocity for a certain range of inclination angles of the plane. Although the friction force is due ...

An upper bound method for the process of plane strain extrusion through a wedge-shaped die is derived. A technique for constructing a kinematically admissible velocity field satisfying the exact asymptotic singular behavior of real velocity fields in the vicinity of maximum friction surfaces (the friction stress at sliding is equal to the shear yield stress on such surfaces) is described. Two s...

The dynamics of Vestfonna ice cap (Svalbard) are dominated by fast-flowing outlet glaciers. Its mass balance is poorly known and affected dynamically by these fast-flowing outlet glaciers. Hence, it is a challenging target for ice flow modeling. Precise knowledge of the basal conditions and implementation of a good sliding law are crucial for the modeling of this ice cap. Here we use the full-S...