The skin friction on a surface is a major concern by engineers. It is widely accepted that turbulent flow has higher friction than laminar flow due to the higher mixing in boundary layer. However, our new high order DNS found that the high friction is generated in a laminar zone in a transitional flow. Whenever the small length scales are generated, the velocity shear becomes very large in the ...

in all engineering applications where solid surfaces slide on each other, friction plays an important role. it becomes even more important, particularly in metal forming processes where the two sliding materials are metallic. among forming processes, forging is an important process, because of improving material structure, mechanical properties and reducing production time. an inverse analysis ...

Finite Element Analysis (FEA) based techniques have become increasingly available to simulate metal cutting process and offer several advantages including prediction of tool forces, distribution of stresses and temperatures, estimation of tool wear, optimization of cutting conditions, tool edge geometry and coatings, and determination of residual stresses on machined surfaces. However, accuracy...

Fluid flow in microchannels or microtubes may differ in terms of wall frictional effects, and hence flow rates, when compared to macrochannels. Focusing on steady laminar fully developed flow of a liquid in different micro-conduits, relative surface roughness is captured in terms of a porous medium layer (PML) model. The new approach allows the evaluation of microfluidics variables as a functio...

This paper describes a numerical investigation of seismicity induced during injection into a single, isolated fracture. A model was developed and used that couples (1) fluid flow and (2) rate and state friction. Rate and state friction theory describes how friction on a fault depends on both sliding velocity and past sliding history. Rate and state friction is used widely in earthquake modeling...

Pressure ulcers, also referred to as pressure sores, decubitus ulcers or bedsores, are defined as an area of localised damage to the skin and underlying tissue caused by pressure, shear force, friction, moisture, and/or a combination of these factors 2. They develop from continuous pressure that affects cellular metabolism and impedes or obstructs capillary blood flow to the skin and underlying...

Isothermal gas flows in microchannels is studied using the lattice Boltzmann method. A novel equation relating Knudsen number with relaxation time is derived. The slipvelocity on the solid boundaries is reasonably realized by combining the bounce-back reflection with specular reflection in a certain proportion. Predicted characteristics in a two-dimensional microchannel flow, including slip-vel...

Although Darcy-Weisbach (D-W) equation has been accepted as a standard resistance equation in pressurized flow, some researchers and engineers still prefer to utilize Hazen-Williams (H-W) equation for analyzing water distribution networks (WDNs) in practice. The main difference between roughness coefficients of these two resistance equations is that D-W friction factor varies with Reynolds numb...

The present paper reports the laminar fluid flow and heat transfer of a heated array of circular-perforated and solid fins mounted over a flat surface using the finite-volume method. One to four circular cross-sectional perforations are made along the length of the fins. The SIMPLE algorithm is used for pressure-velocity coupling and the second order upwind technique is employed to discreti...