Slip velocity and slip layer thickness in flow of concentrated suspensions

Abstract

ABSTRACT:The rheological characterization of highly filled suspensions consisting of a Newtonian matrix (hydroxyl-terminated polybutadiene), mixed with two different sizes of aluminum powder (30% and above by volume) and two different sizes of glass beads (50% and above by volume), was performed using a parallel disk rheometer with emphasis on the wall slip phenomenon. The effects of the solid content, particle size, type of solid particle material, and temperature on slip velocity and slip layer thickness were investigated. Suspensions of small particles of aluminum (mean diameter of 5.03 m) did not show slip at any concentration up to the maximum packing fraction. However, suspensions of the other particles exhibited slip at the wall, at concentrations close to their maximum packing fraction. In these suspensions, the slip velocity increased linearly with the shear stress, and at constant shear stress, the slip velocity increased with increasing temperature. The slip layer thickness increased proportionally with increasing size of the particles for the glass beads. Up to a certain value of (filler content/maximum packing fraction), / m , the slip layer thickness divided by the particle diameter, ␦/D P , was 0, but it suddenly increased and reached a value that was independent of / m and the temperature. On average, the ratio of ␦/D P was 0.071 for aluminum and 0.037 for glass beads.

Rheological measurements of large particles in high shear rate flows

“…39 While these depletion layers may be smaller than a particle diameter, they can significantly change the apparent viscosity. 3 In addition, the radial force in a cylindrical geometry due to differences in fluid and particle densities may accentuate the depletion layer on the inner or outer cylinder surfaces.…”

Rheological Characterization of Powder Mixture Including a Space Holder and Its Application to Metal Injection Molding

“…Without considering the slip phenomenon, the viscosity is eventually underestimated and a filling simulation based on viscosity without slip considerations results in misleading results. One of the models can describe the slip phenomenon as a slip velocity model, and the velocity profile of the fluid can change at the wall, as shown in Figure 5 [14]. …”

“…Without considering the slip phenomenon, the viscosity is eventually underestimated and a filling simulation based on viscosity without slip considerations results in misleading results. One of the models can describe the slip phenomenon as a slip velocity model, and the velocity profile of the fluid can change at the wall, as shown in Figure 5 [14]. Metals 2017, 7, x FOR PEER REVIEW 7 of 17 As shown in Figure 5, if there is a slip velocity (Vs) at the wall, it can be measured using Mooney's method and related equations can be written as follows [15]:…”

Slip Velocity Distribution on MHD Oscillatory Heat and Mass Transfer Flow of a Viscous Fluid in a Parallel Plate Channel

“…Also, wall slip can occur in the working fluid contains concentrated suspensions. Soltani and Yilmazer [23] discussed on slip velocity and slip layer thickness in flow of concentrated suspensions. However, the literature lacks studies that take into account the possibility of fluid slippage at the wall under vibrating conditions.…”