scholarly journals Gravity Flow of Granular Materials in Conical Hoppers

1979 ◽  
Vol 46 (3) ◽  
pp. 529-535 ◽  
Author(s):  
T. V. Nguyen ◽  
C. Brennen ◽  
R. H. Sabersky
Keyword(s):  
Experimental Data ◽  
Approximate Solution ◽  
Granular Material ◽  
Granular Materials ◽  
Flow Rate ◽  
Yield Condition ◽  
Wall Stress ◽  
Perfectly Plastic ◽  
Analytical Expressions ◽  
Conical Hopper

An approximate solution to the flow of a cohesionless granular material in a conical hopper is presented. The material is modeled as a perfectly plastic continuum which satisfies the Mohr-Coulomb yield condition. Analytical expressions of the mass flow rate and the wall stress are derived and compared to some experimental data and other analyses.

Discharge of Granular Materials From Hoppers With Various Exit Geometries

2007 ◽  
Author(s):  
Hojin Ahn ◽  
Erkan Yilmaz ◽  
Mustafa Yilmaz ◽  
Abdulcelil Bugutekin
Keyword(s):  
Experimental Data ◽  
Velocity Profile ◽  
Granular Materials ◽  
Coming Out ◽  
Discharge Coefficient ◽  
Preliminary Investigation ◽  
Visual Observation ◽  
Glass Beads ◽  
The Other ◽  
Conical Hopper

The discharge of glass beads from axisymmetric hoppers was experimentally investigated. Two types of hoppers were employed: one was of conical hoppers with different angles and the other was nozzle-shaped. The result showed that, for a conical hopper with a hopper angle greater than 45°, the hopper angle had little effect on the discharge coefficient. On the other hand, for a hopper angle less than 45°, the discharge coefficient rapidly increased with decreasing hopper angle. The present data agreed well with other experimental data available in the literature. The discharge coefficient of the nozzle-shaped hopper was measured to be as considerably high as that of a conical hopper with the hopper angle of 10°. Preliminary investigation on velocity profiles at hopper exits was conducted by examining the traces of particles in digital photographs. Visual observation on the degree of spread of the jets of particles coming out of hoppers with different hopper angles indicated that the velocity profile at the exit for a narrow hopper was more uniform than that for a wide hopper.

Some axially symmetric flows of Mohr–Coulomb compressible granular materials

1992 ◽  
Vol 438 (1902) ◽  
pp. 67-93 ◽  
Keyword(s):  
Granular Material ◽  
Granular Materials ◽  
Yield Condition ◽  
Polar Coordinates ◽  
Flow Rule ◽  
Physical Parameters ◽  
Alternative Theory ◽  
Axially Symmetric ◽  
Special Cases ◽  
Associated Flow Rule

In this paper we consider a number of axially symmetric flows of compressible granular materials obeying the Coulomb–Mohr yield condition and the associated flow rule. We pay particular attention to those plastic régimes and flows not included in the seminal work of Cox, Eason & Hopkins (1961). For certain plastic régimes, the velocity equations uncouple from the stress equations and the flow is said to be kinematically determined. We present a number of kinematically determined flows and the development given follows the known solutions applicable to the so-called ‘double-shearing’ model of granular materials which assumes incompressibility and for which the governing equations are almost the same. Similarly, for certain other plastic régimes the stresses may be completely determined without reference to the velocity equations and these are referred to as statically determined flows. In the latter sections of the paper we examine statically determined flows arising from the assumption that the shear stress in either cylindrical or spherical polar coordinates is zero. In the final section we present a numerical solution, which incorporates gravitational effects, for the flow of a granular material in a converging hopper. In addition, we examine the Butterfield & Harkness (1972) modification of the double-shearing model of granular materials which formally includes both the double-shearing theory and the Coulomb–Mohr flow rule theory as special cases. Moreover, for kinematically determined régimes, the velocity equations are the same apart from a different constant, while for statically determined régimes the governing velocity equations are slightly more complicated, involving another constant which is a different combination of the basic physical parameters. Thus some of the solutions presented here can be immediately extended to this alternative theory of granular material behaviour and therefore the prospect arises of devising experiments which might validate or otherwise one theory or the other.

An Approximate Solution for the Thermal Performance of a Stirling-Engine Regenerator

1969 ◽  
Vol 91 (2) ◽  
pp. 109-112 ◽  
Author(s):  
E. B. Qvale ◽  
J. L. Smith
Keyword(s):  
Experimental Data ◽  
Approximate Solution ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Performance ◽  
Closed Form Solution ◽  
Form Solution ◽  
Pressure Variation ◽  
Stirling Engine ◽  
The One

An approximate closed-form solution for the thermal performance of a Stirling-engine regenerator is derived. The solution is for sinusoidal mass flow rate and sinusoidal pressure variation with a phase angle relative to the mass flow. The solution provides the net enthalpy flux along the regenerator and the change of phase between the mass flow and the pressure. The method is similar to the one developed by Rea [1], and the results agree well with his experimental data.

Utilization of Waste of Enzymes Biomass as Biosorbent for the Removal of Dyes from Aqueous Solution in Batch and Fluidized Bed Column

2020 ◽  
Vol 71 (1) ◽  
pp. 1-12
Author(s):  
Salman H. Abbas ◽  
Younis M. Younis ◽  
Mohammed K. Hussain ◽  
Firas Hashim Kamar ◽  
Gheorghe Nechifor ◽  
...  
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Particle Size ◽  
Adsorption Capacity ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Fungal Biomass ◽  
Solution Flow Rate ◽  
Maximum Adsorption Capacity ◽  
Solution Flow

The biosorption performance of both batch and liquid-solid fluidized bed operations of dead fungal biomass type (Agaricusbisporus ) for removal of methylene blue from aqueous solution was investigated. In batch system, the adsorption capacity and removal efficiency of dead fungal biomass were evaluated. In fluidized bed system, the experiments were conducted to study the effects of important parameters such as particle size (701-1400�m), initial dye concentration(10-100 mg/L), bed depth (5-15 cm) and solution flow rate (5-20 ml/min) on breakthrough curves. In batch method, the experimental data was modeled using several models (Langmuir,Freundlich, Temkin and Dubinin-Radushkviechmodels) to study equilibrium isotherms, the experimental data followed Langmuir model and the results showed that the maximum adsorption capacity obtained was (28.90, 24.15, 21.23 mg/g) at mean particle size (0.786, 0.935, 1.280 mm) respectively. In Fluidized-bed method, the results show that the total ion uptake and the overall capacity will be decreased with increasing flow rate and increased with increasing initial concentrations, bed depth and decreasing particle size.

scholarly journals Quantitative Monitoring of Dynamic Blood Flows Using Coflowing Laminar Streams in a Sensorless Approach

2021 ◽  
Vol 11 (16) ◽  
pp. 7260
Author(s):  
Yang Jun Kang
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Blood Viscosity ◽  
Measurement Errors ◽  
Present Method ◽  
Test Fluid ◽  
Constant Flow Rate ◽  
Rbc Aggregation ◽  
Sinusoidal Flow ◽  
Analytical Expressions

Determination of blood viscosity requires consistent measurement of blood flow rates, which leads to measurement errors and presents several issues when there are continuous changes in hematocrit changes. Instead of blood viscosity, a coflowing channel as a pressure sensor is adopted to quantify the dynamic flow of blood. Information on blood (i.e., hematocrit, flow rate, and viscosity) is not provided in advance. Using a discrete circuit model for the coflowing streams, the analytical expressions for four properties (i.e., pressure, shear stress, and two types of work) are then derived to quantify the flow of the test fluid. The analytical expressions are validated through numerical simulations. To demonstrate the method, the four properties are obtained using the present method by varying the flow patterns (i.e., constant flow rate or sinusoidal flow rate) as well as test fluids (i.e., glycerin solutions and blood). Thereafter, the present method is applied to quantify the dynamic flows of RBC aggregation-enhanced blood with a peristaltic pump, where any information regarding the blood is not specific. The experimental results indicate that the present method can quantify dynamic blood flow consistently, where hematocrit changes continuously over time.

A Technique for the Laboratory Determination of Recirculation in Single Needle Dialysis

1993 ◽  
Vol 16 (2) ◽  
pp. 63-70 ◽  
Author(s):  
N.A. Hoenich ◽  
P.T. Smirthwaite ◽  
C. Woffindin ◽  
P. Lancaster ◽  
T.H. Frost ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Experimental Results ◽  
New Technique ◽  
Treatment Efficiency ◽  
Single Lumen ◽  
Theoretical Predictions ◽  
Lumen Catheter ◽  
A New Technique

Recirculation is an important factor in single needle dialysis and, if high, can compromise treatment efficiency. To provide information regarding recirculation characteristics of access devices used in single needle dialysis, we have developed a new technique to characterise recirculation and have used this to measure the recirculation of a Terumo 15G fistula needle and a VasCath SC2300 single lumen catheter. The experimentally obtained results agreed well with those established clinically (8.5 ± 2.4% and 18.4 ± 3.4%). The experimental results have also demonstrated a dependence on access type, pump speeds and fistula flow rate. A comparison of experimental data with theoretical predictions showed that the latter exceeded those measured with the largest contribution being due to the experimental fistula.

scholarly journals A mesoscopic model for compression of granular materials

2018 ◽  
Vol 183 ◽  
pp. 01054
Author(s):  
Elisha Rejovitzky
Keyword(s):  
Experimental Data ◽  
Wave Propagation ◽  
Granular Materials ◽  
Mechanical Model ◽  
Sound Speed ◽  
Bulk Material ◽  
High Sensitivity ◽  
Water Fraction ◽  
Protective Structures ◽  
Solid Spheres

The design of protective structures often requires numerical modeling of shock-wave propagation in the surrounding soils. Properties of the soil such as grain-grading and water-fraction may vary spatially around a structure and among different sites. To better understand how these properties affect wave propagation we study how the meso-structure of soils affects their equation of state (EOS). In this work we present a meso-mechanical model for granular materials based on a simple representation of the grains as solid spheres. Grain-grading is prescribed, and a packing algorithm is used to obtain periodic grain morphologies of tightly packed randomly distributed spheres. The model is calibrated by using experimental data of sand compaction and sound-speed measurements from the literature. We study the effects of graingrading and show that the pressures at low strains exhibit high sensitivity to the level of connectivity between grains. At high strains, the EOS of the bulk material of the grains dominates the behavior of the EOS of the granular material.

Investigation of Quench-16 Experiment With MELCOR Computer Code

2014 ◽  
Author(s):  
Petya Vryashkova ◽  
Pavlin Groudev ◽  
Antoaneta Stefanova
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Initial Temperature ◽  
Computer Code ◽  
Air Flow Rate ◽  
Fuel Rod ◽  
Fuel Bundle ◽  
Oxygen Starvation ◽  
Air Ingress ◽  
Good Agreement

This paper presents a comparison of MELCOR calculated results with experimental data for the QUENCH-16 experiment. The analysis for the air ingress experiment QUENCH-16 has been performed by INRNE. The calculations have been performed with MELCOR code. The QUENCH-16 experiment has been performed on 27-th of July 2011 in the frame of the EC-supported LACOMECO program. The experiments have focused on air ingress investigation into an overheated core following earlier partial oxidation in steam. QUENCH-16 has been performed with limited pre-oxidation and low air flow rate. One of the main objectives of QUENCH-16 was to examine the interaction between nitrogen and oxidized cladding during a prolonged period of oxygen starvation. The bundle is made from 20 heated fuel rod simulators arranged in two concentric rings and one unheated central fuel rod simulator, each about 2.5 m long. The tungsten heaters were surrounded by annular ZrO2 pellets to simulate the UO2 fuel. The geometry and most other bundle components are prototypical for Western-type PWRs. To improve the obtained results it has been made a series of calculations to select an appropriate initial temperature of the oxidation of the fuel bundle and modified correlation oxidation of Zircaloy with MELCOR computer code. The compared results have shown good agreement of calculated hydrogen and oxygen starvation in comparison with test data.

scholarly journals A frictional Cosserat model for the slow shearing of granular materials

2002 ◽  
Vol 457 ◽  
pp. 377-409 ◽  
Author(s):  
L. SRINIVASA MOHAN ◽  
K. KESAVA RAO ◽  
PRABHU R. NOTT
Keyword(s):  
Angular Velocity ◽  
Granular Material ◽  
Shear Layer ◽  
Granular Materials ◽  
Layer Thickness ◽  
Couette Flow ◽  
Velocity Fields ◽  
Cosserat Continuum ◽  
Cosserat Model ◽  
Cylindrical Couette Flow

A rigid-plastic Cosserat model for slow frictional flow of granular materials, proposed by us in an earlier paper, has been used to analyse plane and cylindrical Couette flow. In this model, the hydrodynamic fields of a classical continuum are supplemented by the couple stress and the intrinsic angular velocity fields. The balance of angular momentum, which is satisfied implicitly in a classical continuum, must be enforced in a Cosserat continuum. As a result, the stress tensor could be asymmetric, and the angular velocity of a material point may differ from half the local vorticity. An important consequence of treating the granular medium as a Cosserat continuum is that it incorporates a material length scale in the model, which is absent in frictional models based on a classical continuum. Further, the Cosserat model allows determination of the velocity fields uniquely in viscometric flows, in contrast to classical frictional models. Experiments on viscometric flows of dense, slowly deforming granular materials indicate that shear is confined to a narrow region, usually a few grain diameters thick, while the remaining material is largely undeformed. This feature is captured by the present model, and the velocity profile predicted for cylindrical Couette flow is in good agreement with reported data. When the walls of the Couette cell are smoother than the granular material, the model predicts that the shear layer thickness is independent of the Couette gap H when the latter is large compared to the grain diameter dp. When the walls are of the same roughness as the granular material, the model predicts that the shear layer thickness varies as (H/dp)1/3 (in the limit H/dp [Gt ] 1) for plane shear under gravity and cylindrical Couette flow.

Thermal Analysis of the Hot Dip-Coating Process

1993 ◽  
Vol 115 (2) ◽  
pp. 453-460 ◽  
Author(s):  
Hui Zhang ◽  
M. Karim Moallemi ◽  
Sunil Kumar
Keyword(s):  
Experimental Data ◽  
Thermal Analysis ◽  
Approximate Solution ◽  
Dip Coating ◽  
Solution Procedure ◽  
Heat Diffusion ◽  
Coating Process ◽  
Parametric Effects ◽  
Simplifying Assumptions ◽  
Axial Heat

In this study a thermal analysis is performed on the hot dip-coating process where solidification of metal occurs on a bar moving through a finite molten bath. A continuum model is considered that accounts for important transport mechanisms such as axial heat diffusion, buoyancy, and shear-induced melt motion in the bath. A numerical solution procedure is developed, and its predictions are compared with those of an analytical approximate solution, as well as available experimental data. The predictions of the numerical scheme are in good agreement with the experimental data. The results of the approximate solution, however, exhibit significant disagreement with the data, which is attributed to the simplifying assumptions used in its development. Parametric effects of the bath geometry, and initial and boundary temperatures and solid velocity, as characterized by the Reynolds number, Grashof number, and Stefan numbers, are presented.

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