https://nova.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:44647 Wed 19 Oct 2022 08:46:30 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:47153 i^/) were determined in a solid-liquid fluidised bed comprising glass particles (d_S = 8 mm, ρ_S = 2230 kg m⁻³) and water as a fluidising medium. Both inter-particle and particle-wall collisions were determined from the time varying jerk data. The particle mean-free path (λ) was then estimated as a distance between two successive peaks in the jerk profile. Finally, dispersion efficient D was computed based on the product of λ and V. Estimated dispersion coefficients were compared with the available correlations and reasonable agreement was obtained.]]> Wed 14 Dec 2022 15:34:32 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:17143 Wed 11 Apr 2018 15:39:34 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:24590 Eo (=ΔρgD²/σ)≤641 and Re≤151. Additionally, results published in the literature encompassing bubbles with lower values of Eo numbers were also considered, such that the overall dependencies of bubble shape, wake characteristics, and drag coefficient over a large range of Eo and Re values can be identified. While it was found that the deformation of the bubbles as predicted through the numerical study can generally replicate experimental observations presented, several limitations were identified, such as in the representation of skirt formation behind a skirted bubble and the formation of satellite bubbles behind a bubble rising at high Reynolds numbers. The dependency of the bubble aspect ratio on the Weber and Morton numbers was confirmed for cases of spherical and ellipsoidal bubbles; whilst for spherical cap and skirted bubbles the aspect ratio was found to depend largely on the Reynolds and Capillary numbers, respectively. Finally, the expansion and formation of closed/open laminar wakes behind the rising bubble were analysed and was found to correlate well with the bubble Re and Eo numbers.]]> Thu 21 Oct 2021 12:53:06 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32959 Thu 16 Aug 2018 13:36:14 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32957 -5 to 5 × 10^-4 m2 s^-1 when energy dissipation rate increased from ~ 0.005-0.01 m² s^-3. Different dispersion correlations were then utilized to describe the intermixing and segregation behaviour for the binary particle species differing in density in terms of axial particle concentration profile using a one-dimensional convection-diffusion model which agreed well with the experimental data. Additionally, a two-dimensional (2D) Eulerian-Eulerian (E-E) model based on kinetic theory of granular flow (KTGF) was used to simulate axial variation of the binary solids concentration which showed good agreement (~ 10% deviation) with the published experimental data. Axial profile of dispersion coefficient predicted by the various correlations exhibited a sharp variation in the intermixing zone formed in between the lower (higher density) and upper particle bed (low density). In this region, CFD model predicted energy dissipation rate increased significantly with liquid superficial velocity which reflected strong phase interactions in the intermixing zone.]]> Thu 16 Aug 2018 13:36:10 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32954 f₁, has been proposed (see for example Joshi et al. (2001)). Briefly, the LSA analysis utilises the velocity fluctuations of both the dispersed and continuous phases associated with the specific energy dissipation rate of the two phase mixture. Typically, the specific energy dissipation rate is correlated with the density of the bed. The previous analysis, however, does not consider the energy input which associated with the turbulence intensity (velocity fluctuations) of the incoming liquid stream. Usually, this component can be ignored in sparged bubble columns because its magnitude is relatively small and it also decays in the axial direction. In plunging liquid jet bubble columns the liquid is introduced as a high speed jet that entrains gas which is then broken into fine bubbles in the Mixing Zone. The bubby mixture then passes into the Two Phase Flow Zone where instabilities can be generated. The Mixing Zone is a region of high energy dissipation resulting in relatively large liquid velocity fluctuations, which can directly influence the instability of the Two Phase Flow Zone. In this study the existing linear stability analysis is modified to include the influence of inlet liquid velocity fluctuations on the stability parameter, f₁. The modified theory is applied to the previous work of Evans (1990) for a plunging liquid jet bubble column to determine the critical gas volume fraction at which transition takes place in the Two Phase Flow Zone. In order to apply the model, drift-flux analysis has been used to obtain bubble diameter as a function of gas and liquid superficial velocities, and computational fluid dynamics has been utilised to quantify the velocity fluctuations of the liquid exiting the Mixing Zone.]]> Thu 16 Aug 2018 13:36:04 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32955 Thu 16 Aug 2018 13:35:45 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32956 -3) spherical glass beads particles of diameter 3, 5 and 8 mm and water as fluidising medium with different particle mass ratios varying from 0.17 to 6.0. In the expanded bed, both segregated and intermixed zones were observed depending on the different particle diameter combinations. In a completely segregated SLFB, the bottom monosized layer exhibited a negative deviation ~23% whereas a positive deviation ~25% was found in the top monosized layer when compared with the corresponding pure monosized system. A small mixing zone spanning approximately two particle diameters thick was observed to exist even in a completely segregated SLFB for higher diameter ratio cases. A slight decrease in the mixing zone height was noted with increasing liquid superficial velocity. For lower diameter ratio cases, a relatively lager mixing zone height was observed which increased with increasing liquid superficial velocity. The bed expansion ratio was noted to decrease with increasing solid mass ratio however it increased with increase in the fluidising velocity ratio following a reasonable power law trend. The expanded bed height of the binary mixture was not entirely additive of its corresponding mono-component bed heights and both positive and negative deviations were observed. Finally, a two-dimensional (2D) Eulerian-Eulerian (E-E) model incorporating the kinetic theory of granular flow (KTGF) was used to quantify the binary system hydrodynamics. The model predicted expanded bed height agreed with experimental measurements within ±6% deviation. Presence of a mixing zone was also confirmed by the CFD model and simulated particle phase volume fraction distribution qualitatively agreed with the experimental visualisations.]]> Thu 16 Aug 2018 13:31:39 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:43290 Thu 15 Sep 2022 12:44:32 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:46070 1). Fast Fourier Transform (FFT) analysis characterized the presence of a bimodal frequency similar to that exhibited by flow past an isolated stationary bluff body.]]> Thu 10 Nov 2022 15:12:01 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:13556 Sat 24 Mar 2018 08:17:06 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:20915 Sat 24 Mar 2018 08:06:12 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:20600 P2/d_P1) and became independent of the foreign particle size for high solid fractions when the fluidised particle size was kept constant. The magnitude of collision force was 10-50 times greater than that of gravitational force and maximally 9 times greater than that of drag force. A correlation describing the collision force as a function of bed voidage was developed for St_p>65 and d_P2/d_P1≤2. A maximum deviation of less than 20% was obtained when the correlation was used for the prediction of particle collision force.]]> Sat 24 Mar 2018 07:55:33 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:27090 Sat 24 Mar 2018 07:40:35 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:28747 d_PD=5–12 mm) and single air bubbles (d_B=1–4 mm) has been measured in a solid–liquid fluidized bed of uniform size borosilicate glass beads (d_P=5 and 8 mm) as a function of liquid superficial velocity. The homogeneity and intensity of the turbulence within the fluidized bed has been quantified and directly related to the slip velocity of the foreign (steel or bubble) particle. It was found that the turbulence resulted in an increase in the computed drag coefficient for all of the experimental conditions investigated.]]> Sat 24 Mar 2018 07:37:35 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:29668 p≤40, ∈_L, _ave≤0.74), particle collisions acted as the main mechanism that drove the dispersion of particles. However, after the system became heterogeneous, the magnitude of the vertical collision force decreased towards zero and correspondingly, the magnitude of the vertical fluid drag force was approaching that of the particle net weight force as the superficial liquid velocity increased. Therefore, in the heterogeneous flow regime (Re_p>40, ∈_L, _ave>0.74), the local turbulence of the fluid flow and particle collisions (if there were any) were found to be the main mechanisms that drove the dispersion of particles in all directions. The dispersion coefficient of individual particles varied significantly throughout the system in the heterogeneous flow regime. The simulation results reasonably agreed with the experimental data and the prediction results by existing correlations.]]> Sat 24 Mar 2018 07:32:22 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26431 Sat 24 Mar 2018 07:27:29 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:30864 Sat 24 Mar 2018 07:26:37 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26045 Sat 24 Mar 2018 07:26:27 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26046 Sat 24 Mar 2018 07:26:26 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26571 Sat 24 Mar 2018 07:26:11 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:25528 -3) were used as fluidised particles. Three different combinations of particle size pairs of both equal and unequal mass ratios were used using a constant liquid (water) superficial velocity of 0.17 ms^-1 in all the cases. Numerically, a two dimensional Eulerian-Eulerian (E-E) CFD model incorporating kinetic theory of granular flow (KTGF) was developed to predict the bed expansion behaviour. It was observed that complete bed segregation occurred when the difference between the solid particle diameters was higher while lower difference in particle diameters led to partial bed segregation. The CFD model also predicted these behaviours which were in good agreement with the experimental data.]]> Sat 24 Mar 2018 07:26:07 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:25529 -3 were fluidised in water. Binary experiments were carried out considering both equal and unequal solid mass ratios ranging from 0.16 to 6.0. The overall bed expansions including segregated and intermixed zones were monitored. The effect of loading pattern on bed expansion was found insignificant in a binary SLFB. In a completely segregated SLFB, bottom mono-component layer displayed a negative deviation up to 30% whereas a positive deviation up to 22% was found in top mono-component layer when compared to respective individual monocomponent SLFBs. The total bed height of binary mixture was found to be unequal to sum of expanded bed height in individual mono-component SLFB, showing either positive or negative deviations. The experimentally observed criterion of the bed independency has been tabulated. Eulerian-Eulerian (E-E) CFD simulations with kinetic theory of granular flow (KTGF) have been performed and compared with the experimental data. The CFD predictions were found to be in good agreement (within ±6 per cent deviation) when compared to experimental results.]]> Sat 24 Mar 2018 07:26:07 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:23747 Sat 24 Mar 2018 07:16:57 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:24402 Sat 24 Mar 2018 07:14:27 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:25003 Sat 24 Mar 2018 07:09:54 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:24063 Sat 24 Mar 2018 07:09:41 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:35930 b = 2.70 and 3.52 mm) rise using the non-intrusive two-dimensional (2D) particle image velocimetry (PIV) at the low Taylor-Reynolds number (Re_λ) ranging from 12 to 60. Using the measured PIV velocity data, the instantaneous pressure fluctuations were estimated by integrating the full viscous form of the Navier-Stokes (N-S) equation and compared with three dimensional (3D) computational fluid dynamics (CFD) simulations. A spectral slope of -7/3 was found in the inertial subrange of the single-phase pressure spectrum. In contrast, the two-phase pressure spectrum exhibited a slope less steep than -7/3 in the inertial subrange because of the extra production of turbulence in the presence of bubble. For single-phase flow, the ratio of pressure integral length scale to the velocity integral length scale (L_p/L) was found to be a constant of about 0.67, and the pressure Taylor microscale (λ_p) was approximately 0.79 ± 0.03 of the velocity Taylor microscale (λ) for a low Reynolds number. The scaling ratio based on the single-phase experimental results were compared with existing theory and DNS results and found to accord well; however, these ratios deviate from theoretical values for two-phase flow. Also, the energy dissipation rate was evaluated based on the pressure spectrum and found the over-predicted (~ 31%) values relative to those calculated from the velocity spectrum.]]> Fri 19 Jun 2020 14:48:42 AEST ]]>