Structure of particle-laden turbulent water jets in still water

Abstract

Abstract--The structure of turbulent, dilute, particle-laden water jets, submerged in still water, was studied both experimentally and theoretically. Nonintrusive measurements were made of mean and fluctuating phase velocities and particle number fluxes. Analysis was used to help interpret the measurements, considering three limiting cases, as follows: (1) locally-homogeneous flow, where relative velocities between the phases are ignored; (2) deterministic separated flow, where relative velocities are considered, but panicle/turbulence interactions are ignored; and (3) stochastic separated flow, where both phenomena are considered using random-walk methods. The locally-homogeneous flow approximation was more effective than for past work involving larger density ratios between the phases; however, stochastic analysis yielded best agreement with measurements. Effects of enhanced drag (due to high relative turbulent intensities of particle motion) and effects of particles on liquid turbulence properties (turbulence modulation), were observed. Several recent proposals for treating these phenomena were examined; however, none appears to be adequate for reliable general use.

Two-phase modeling of turbulence in dilute sediment-laden, open-channel flows

“…For the constants involved in the K-ε model, Squires and Eaton [64] concluded that for dilute flows with mass loadings below 0.2, the modification in the values of the constants are small (although some caution should be taken in cases of preferential concentration of particles). Therefore, we have used the unmodified values of the constants in the turbulence models, following customary approaches in most papers (see, for instance, [2,14,23,32,55,73]). In the case of the K-ω model, [43,74] have used the same constants that were suggested by Wilcox [72].…”

Inter-phase interaction in a turbulent, vertical channel flow laden with heavy particles. Part II: Two-phase velocity statistical properties

“…Ferrante and Elghobashi [10] analyzed the mechanism of particle modification of low-wavenumber energy transfer. In experimental studies on jet two-phase turbulence, large particles enhanced gas-phase turbulence intensity, while small particles attenuated turbulence intensity [2,[11][12][13][14][15]. The two-phase inter-phase interaction in a turbulent channel flow laden with heavy particles has not been sufficiently investigated.…”

“…Large particles can augment turbulence intensity due to unsteady particle wakes or the superposition of many randomly positioned laminar or laminar-like wakes [2][3][4]. However, extra dissipation of turbulence by particles can cause turbulence attenuation.…”

Numerical Simulation of Sediment-Laden Jets in Static Uniform Environment using Eulerian Model

“…Brush (1962) investigated the spreading rate of the velocity of the solid phase and fluid phase in the vertically downward jet as a function of particle size which was also obtained from photographic measurements of sand jets by Mazurek et al (2002). The velocity and turbulence characteristics of a vertically downward jet of glass spheres and water were studied by Parthasarathy and Faeth (1987), with initial particle concentrations up to 4.8%, using a laser Doppler anemometer. Jiang et al (2005) measured the velocities of both lower-density fluorescent hollow glass beads and polyamide particles as a two-phase vertically downward jet through particle image velocimetry, and theoretically derived an equation for vertically upward jet that compared well with experimental measurements for a ground deposit made by Neves and Fernando (1995).…”