wall friction

wall friction

[′wȯl ‚frik·shən]
(fluid mechanics)
The drag created in the flow of a liquid or gas because of contact with the wall surfaces of its conductor, such as the inside surfaces of a pipe.
References in periodicals archive ?
Physical characterization includes methods to measure particle density, bulk density, compressibility, elasticity, unconfined yield strength, effective angle of internal friction, wall friction angle, and permeability.
Measurements will be performed in a wind tunnel and in a water channel at the University of Southampton (UoS), using a force balance to directly measure the wall friction, particle image velocimetry to measure the local flow structure, and planar-laser-induced fluorescence to measure the local dispersion for a variety of different patch topologies.
In sections on functional and electronic materials, high-performance structural material, and materials processing technology, 28 papers discuss such topics as the controllable synthesis of mono-dispersed metal oxide nanostructures with a solvothermal route and their catalytic properties, hydration mechanisms of Portland cement with magnesium slag, the mesoscopic simulation analysis of the influence of die wall friction on the compression process of powder particles, and the effect of coiling temperature and cold rolling reduction on the planar anisotropy of low-carbon steel alloyed with titanium.
Shear cell technology provides the solution through the use of an annular shear cell and a wall friction lid.
Evaluation of the wall friction coefficient for a sinusoidal corrugated wall is determined as:
The FT4 Powder Rheometer from Freeman Technology is a universal powder tester--three instruments in one, combining the proprietary blade methodology for measuring flow energy with a range of shear cells, wall friction modules and other accessories for measuring bulk properties.
The FT4 Powder Rheometer offers dynamic, bulk, and shear property testing capabilities and incorporates well-defined methodologies and software for the measurement and interpretation of wall friction angles.
This article focuses on the known complications associated with uniaxial compression of powders in a cylinder due to sample-wall friction, and presents an instrument configuration and analysis technique that isolates effects of wall friction.
However, with the roughness reduced on the inner wall, the small convex parts are all completely submerged in the viscous sublayer and the gas pipeline becomes "hydraulic smooth pipe" That means even though the coating surface is smoothed further, the wall friction is difficult to further reduce.
This approach creates high wall friction, which generates fine resin dust that carries static charge, making it stick to pellets and silo walls and roofs, causing periodic "dust surges.
The Brookfield Powder Flow Tester features a variety of test options including: flow function, time consolidation, wall friction and bulk density.
During the expansion phase, reverse squish as the flow exits from the piston bowl and wall friction contribute to the sudden fall of the swirl velocity.