Solid Particle Demixing in a Suspension Flow of Viscous Gas

1975 ◽  
Vol 97 (1) ◽  
pp. 106-111 ◽  
Author(s):  
A. Hamed ◽  
W. Tabakoff

The motion of a medium consisting of an incompressible viscous fluid and suspended solid particles was analyzed from the standpoint of continuum mechanics. It was assumed that the particles’ translational and rotational velocities were different from those of the fluid. A numerical scheme was used to determine the non-equilibrium particulate flow properties as well as their equilibrium and frozen values. The results are presented for the case of particulate flow due to the impulsive motion of an infinite flat plate in a suspension. A demixed region, with no particles present, was found to develop near the plate due to particle migration away from the wall. Similar demixed particle regions were noticed in the experimental data of particulate flows in pipes and channels.

1986 ◽  
Vol 19 (6) ◽  
pp. 507-513 ◽  
Author(s):  
SHIGEHARU MOROOKA ◽  
TETSUYA MIZOGUCHI ◽  
TOKIHIRO KAGO ◽  
YASUO KATO ◽  
NOBUYUKI HIDAKA

2014 ◽  
Vol 8 (1) ◽  
pp. 1-11 ◽  
Author(s):  
M. Azimian ◽  
M. Lichti ◽  
H.-J. Bart

Hydroabrasion in particulate flows plays an important role in various industrial and natural processes. To predict the influence of it in a pipeline, channel or a fitting, it is essential to characterize the effects in a simple standardized geometry. An example to this is a pipe channel with a cylindrical obstacle adjusted inside the channel perpendicular to the flow direction. Results of flow field are generated by using the non-invasive Laser/Phase Doppler Anemometry (LDA/PDA) measurement technique. The velocity profiles of single phase and particulate flow from computational fluid dynamics (CFD) and discrete element method (DEM) simulations were validated by the LDA experimental data. The simulations were performed on the basis of Euler-Lagrange technique for both CFD and DEM. The measurements show that a Karman vortex field forms behind the obstacle and particles move inside this field with an average negative velocity of up to 25% of the fully developed velocity field. A comparison of CFD and DEM results with experimental data showed that in Karman velocity field, the CFD results fit better to the LDA measurements. In the fully developed flow region and also above and under the vortex field behind the obstacle, the DEM results match better with the LDA data.


2021 ◽  
Vol 3 (2) ◽  
pp. 36-42
Author(s):  
Theresia Evila Purwanti Sri Rahayu ◽  
Rosita Dwityaningsih ◽  
Murni Handayani ◽  
Khoeruddin Witriansyah ◽  
Ayu Pramita

Wastewater resulted from the batik dying process is known for its environmentally hazardous substances including hazardous natural and synthetic organic matter, suspended particles, and hazardous metal. But in the micro and medium scale batik textile business, wastewater treatment is mostly not carried because it does not give benefit for the owner. Economical wastewater treatment constructions can be an alternative for the business owner for their free operational cost. Batik wastewater treatment ought to be carried out to meet government standards but most importantly to decrease hazardous pollutant’s concentrations so it does not harm the environment. This society service project aims to provide alternatively economical wastewater treatment for batik business owners by applying simples and cheapest yet effective treatment methods to reduce pollutant concentrations in wastewater. Methods applied in this project including sedimentation, filtration, and landfill-bioremediation. The laboratorium analysis result shows that sedimentation and filtration are significantly reduced total suspended solid particles in wastewater from 2450 to 100 mg/L in line with wastewater decoloring from dark blue to clear yellow.


Author(s):  
P. Bhattacharya ◽  
S. Nara ◽  
P. Vijayan ◽  
T. Tang ◽  
W. Lai ◽  
...  

A nanofluid is a fluid containing suspended solid particles, with sizes of the order of nanometers. The nanofluids are better conductors of heat than the base fluid itself. Therefore it is of interest to measure the effective thermal conductivity of such a nanofluid. We use temperature oscillation technique to measure the thermal conductivity of the nanofluid. However, first we evaluate the temperature oscillation technique as a tool to measure thermal conductivity of water. Then we validate our experimental setup by measuring the thermal conductivity of the aluminum oxide-water nanofluid and comparing our results with previously published work. Finally, we do a systematic series of measurements of the thermal conductivities of aluminum oxide-water nanofluids at various temperatures and explain the reasons behind the dependence of the enhancement in thermal conductivity of the nanofluid on temperature.


2020 ◽  
Vol 198 ◽  
pp. 01030
Author(s):  
Wang Tieli

By analyzing the momentum transfer and velocity both of solid particles and water over the acceleration time of solid particles, as well as interaction mechanism between water and solid particals, a new model is proposed to predict friction loss for setting slurry flow in inclined pipe. The hydraulic gradient formula for inclined pipes summarized by the author is confirmed by a large amount of experimental data. The results show that the deviation between the theoretical value of the model proposed by the author and the measured value is not more than 13.33%, which is the smallest among all reports.


Author(s):  
Yu. A. Taran ◽  
A. V. Kozlov ◽  
A. L. Taran

The aim of the work is to consider the mechanism of clogging the pores of the filter unit by small particles from the flow of filtrate inside them. Theoretical ideas about the process of filtering with the deposition of small particles from the filtrate on the pore walls and attribution of its fundamentals to restructuring from the original structure to the final structure allow to describe the process of clogging the pores using well studied concepts of known processes with phase transformations (in particular, crystallization). Based on this analogy and the approach to the description of the transformation of the "old" structure into a "new" one in time, using experimental data and their processing we calculated the rate of nucleation of the sediment centers (ωnucl), the linear (υlin) and volumetric rates of sediment plaques growth in the pores of the filter unit at different values of the process driving force, at different pressure difference in the system, and at different concentrations of solid particles in the suspension. Interpolation and extrapolation dependences were obtained for analyzing the mechanisms of sediments formation and growth for determining and calculating these (ωnucl, υlin) rates. Using the concepts of nonequilibrium thermodynamics to assess the influence of the driving forces we studied their influence (changes in the concentration of solid particles in the filtrate suspension and pressure drop across the filtering layer) on the dynamics of the filtration process. Using the data obtained it is possible to find the degree of clogging of through pores, which determines the filtration conditions, the filter septum type, and the filter overall dimensions.


1975 ◽  
Vol 189 (1) ◽  
pp. 367-373
Author(s):  
B. N. Cole ◽  
M. R. Baum ◽  
F. R. Mobbs

Thermal and velocity lag prior to the gas discontinuity are shown to have a significant effect on the properties of the relaxation zone of a gas-solid flow shock wave. The results obtained by previous workers assuming equilibrium conditions are not therefore applicable to shock waves formed in gas-solid nozzle flows where considerable disequilibrium already exists. The variations of the relevant flow properties in the relaxation zone are interpreted physically in terms of the magnitude and sign of the heat, momentum and kinetic energy transfer between the solid particles and the gas.


1986 ◽  
Author(s):  
W. Tabakoff ◽  
A. Hamed

Gas turbine engines operating in dusty environments are exposed to erosion and performance deterioration. In order to provide the basis for calculating the erosion and performance deterioration of turbines using pulverized coal, an investigation is undertaken to determine the three dimensional particle trajectories in a two stage turbine. The solution takes into account the influence of the variation in the three dimensional flow field. The change in particle momentum due to their collision with the turbine blades and casings is modeled using empirical equations derived from experimental Laser Doppler Velocimetry (LDV) measurements. The results show the three dimensional trajectory characteristics of the solid particles relative to the turbine blades. The results also show that the particle distribution in the flow field are determined by particle-blade impacts. The results obtained from this study indicate the turbine blade locations which are subjected to more blade impacts and hence more erosion damage.


Author(s):  
Yanhong Li ◽  
Liquan Xie ◽  
Tsung-chow Su

Vegetation has already been acknowledged to have the ability to remove fine solid pollutants by retention and absorption, and is widely used in the biorestoration engineering of natural shallow water flow. Vegetation usually takes a long time to obtain the expected removal rate. Therefore, vegetation is not applicable for some urgent or pressing situations. In addition, in traditional biorestoration engineering, solid pollutants usually deposit in the soil of flow bed, which infiltrates into the far-field and accumulates in crops to threaten human health. Herein, we propose a new biotechnique of foliage capture by designing a cave on the top of a vegetation canopy, which is aimed to enhance the removal efficiency (i.e., achieve quick removal) and avoid the soil deposition of pollutants. The effectiveness and efficiency of this new design were validated by a set of indoor water flume experiments, with one flat canopy top configuration serving as the model of a traditional bioretention system and three cave configurations of differing aspect ratios. The results showed that compared with that of the flat canopy top, the total amount of foliage-captured solid particles for the three caved canopies increased by 3.8, 7.3, and 12.2 times. Further, we found that the foliage-capture efficiency depended on the aspect ratio of the canopy cave. The results revealed that the effectiveness of foliage capture and the enhanced efficiency were mainly from three hydrodynamic mechanisms: (i) as flow penetrated the cave boundary from the above-canopy region to the within-canopy region, it entrained solid pollutants to collide with the foliage and increased their fate of capture; (ii) the large eddy vortices of turbulence broke due to the increasing canopy resistance, which resulted in enhanced mixing dynamics for fine, suspended, solid pollutants to collide into foliage; and (iii) the flow shear along the cave boundary decreased, which provided a reduced lift force for solid pollutants to suspend or resuspend. Comparisons between the flat canopy and caved canopies of three aspect ratios showed that the design of the canopy cave is highly significant for capture efficiency.


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