Relationships between velocity profiles and drag reduction in turbulent fiber suspension flow

Abstract

Equilibrium data for the sorption of oxygen, nitrogen, carbon monoxide, and methane in 5A molecular sieve are analyzed in terms of a simple theoretical model isotherm. The model provides an excellent correlation of the single-component isotherms over the entire concentration range, and it is shown that equilibrium data for sorption of binary mixtures of these gases are correcdy predicted by the model using the parameters (Henry constants and molecular volumes) derived from analysis of the singlecomponent isotherms. The model predicts that mixtures of two sorbates with euual molecular volumes should show amroximatelv ideal solution behavilr in the adsorbed phase. The experim&h data df Lederman for the sorption of nitrogen-methane mixtures show the expected behavior over a wide range of pressures. SCOPEIndustrial adsorption separation processes generally involve the sorption of multicomponent mixtures, and a reliable predictive method of estimating mixture equilibria from single-component isotherm data is required for the proper design and modeling of such processes. Of the available methods which have so far been suggested, the method of Myers and Prausnitz (1965), which is based on the assumption of ideal behavior in the adsorbed phase,

Turbophoresis attenuation in a turbulent channel flow with polymer additives

“…These trends are consistent with available literature for channel flow with polymer additives (e.g. De Angelis et al 2002) and are common also to other drag reducing flows (Virk 1975;Lee & Duffy 1976;Tsinober 1990;De Angelis et al 2003;Van Den Berg et al 2005). Figure 2 shows instantaneous snapshots of a wall-parallel plane in the buffer region (5 < y + < 30).…”

“…Hence, we argue that the turbophoretic drift is lower in all turbulent flows when drag is reduced, e.g. fibre and bubble suspensions and magnetohydrodynamics (MHD) (see Lee & Duffy 1976;Tsinober 1990;Van Den Berg et al 2005, among others). A simple predictive model is derived in the limit of small-particle inertia to quantify the reduction of turbophoresis.…”

In‐line jet mixing of liquid‐pulp‐fiber suspensions: Effect of fiber properties, flow regime, and jet penetration

“…It is generally believed that drag reduction is due to the suppression of turbulent eddies by fibers or other particles. Several studies have suggested that drag reduction in fiber suspensions is especially due to dampening of radial velocity fluctuations in the turbulent core, in contrast to drag reduction in polymer solutions, in which drag reduction is due to dampening near the wall . This implies less turbulent dispersion and reduced lateral mixing, which appears to contradict the experimental results of improved mixing for the hardwood fibers.…”

Reviews on drag reducing polymers

“…On the other hand, Lee and Duffy [122] discovered that the near-wall flow behavior was unaffected by the presence of fibers, and they proposed that the DR by fibers was due to the turbulence suppression in the turbulent core region.…”