scholarly journals Tunable viscosity modification with diluted particles: when particles decrease the viscosity of complex fluids

2019 ◽  
Vol 297 (11-12) ◽  
pp. 1507-1517 ◽  
Author(s):  
Manuchar Gvaramia ◽  
Gaetano Mangiapia ◽  
Vitaliy Pipich ◽  
Marie-Sousai Appavou ◽  
Sebastian Jaksch ◽  
...  
Keyword(s):  
Complex Fluids ◽  
Stage Structure ◽  
Solid Particles ◽  
Viscosity Reduction ◽  
Spherical Particles ◽  
Steady Increase ◽  
Two Stage ◽  
Apparent Contradiction ◽  
Domain Structures ◽  
Lubrication Effect

Abstract While spherical particles are the most studied viscosity modifiers, they are well known only to increase viscosities, in particular at low concentrations of approx. 1%. Extended studies and theories on non-spherical particles in simple fluids find a more complicated behavior, but still a steady increase with increasing concentration. Involving platelets in combination with complex fluids—in our case, a bicontinuous microemulsion—displays an even more complex scenario that we analyze experimentally and theoretically as a function of platelet diameter using small angle neutron scattering, rheology, and the theory of the lubrication effect, to find the underlying concepts. The clay particles effectively form membranes in the medium that itself may have lamellar aligned domains and surfactant films in the case of the microemulsion. The two-stage structure of clay and surfactant membranes explains the findings using the theory of the lubrication effect. This confirms that layered domain structures serve for lowest viscosities. Starting from these findings and transferring the condition for low viscosities to other complex fluids, namely crude oils, even lowered viscosities with respect to the pure crude oil were observed. This strengthens our belief that also here layered domains are formed as well. This apparent contradiction of a viscosity reduction by solid particles could lead to a wider range of applications where low viscosities are desired. The same concepts of two-stage layered structures also explain the observed conditions for extremely enhanced viscosities at particle concentrations of 1% that may be interesting for the food industry.

Comparative Study on Compositions of Oil-Water Transition Layer before and after ClO2-Treatment Process

2013 ◽  
Vol 652-654 ◽  
pp. 749-752
Author(s):  
Dan Dan Yuan ◽  
Hong Jun Wu ◽  
Hai Xia Sheng ◽  
Xin Sui ◽  
Bao Hui Wang
Keyword(s):  
Chemical Composition ◽  
Transition Layer ◽  
Solid Phase ◽  
Settling Tank ◽  
Physical Structure ◽  
Solid Particles ◽  
Viscosity Reduction ◽  
Insoluble Residue ◽  
Before And After ◽  
Oil Water

In order to meet the need of separating oil from water in the settling tank of the oilfield, ClO2 treatment for oil-water transition layer in settling tank is introduced. The field test displayed that the technique was achieved by a good performance. For understanding the oxidation and mechanism, compositions of oil-water transition layer were comparatively studied for before/after ClO2-treatment in this paper.The experimental results show that the compositions before and after ClO2-treatment, including physical structure and chemical composition, were varied in the great extension. The physical structure, consisting of water, oil and solid phase, was reduced to less than 5% of water and 0.5% of solid particle and increased to 95% of oil in layer compared with before-treatment, easily leading to clearly separating water from oil. The chemical composition of iron sulfide and acid insoluble substance in solid phase was decreased to more than 90% while the carbonate was reduced more than 70% . After the treatment, the viscosity reduction of the water phase in the layer was reached to 50% after oxidation demulsification with ClO2. The chemistry was discussed based on the principles and experiments. Due to ClO2 destroying (oxidizing) the rigid interface membrane structure which is supported by natural surfactant, polymer and solid particles with interface-active materials, the action accelerates the separating of water and oil and sedimentation of insoluble residue of acid in the layer. By demonstrating the experimental data and discussion, we can effectively control the oxidation performance of chlorine dioxide, which is very meaningful for oilfield on the aspect of stable production of petroleum.

Raman-Microsampling Technique Applying Optical Levitation by Radiation Pressure

1984 ◽  
Vol 38 (1) ◽  
pp. 78-83 ◽  
Author(s):  
R. Thurn ◽  
W. Kiefer
Keyword(s):  
Radiation Pressure ◽  
Optical Potential ◽  
Solid Particles ◽  
Spherical Particles ◽  
Exciting Light ◽  
Potential Wells ◽  
Ion Laser ◽  
Optical Levitation ◽  
Argon Ion ◽  
Microprobe Technique

We report on a new Raman microprobe technique where micron-sized solid particles are trapped in stable optical potential wells using only the force of radiation pressure from a continuous gas laser. We demonstrate this technique with Raman spectra from spherical and non-spherical particles of sizes ranging between 10–30 μm. The particles are stably supported by a vertical directed focused TEM00-mode cw argon ion laser of ∼500 mW. The latter simultaneously serves as the exciting light source. Several suggestions for improvements of this technique are made.

scholarly journals The Dynamics of Suspended Solid Particles in a Two Stage Gas Turbine

1986 ◽  
Author(s):  
W. Tabakoff ◽  
A. Hamed
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Suspended Solid ◽  
Solid Particles ◽  
Two Stage ◽  
Particle Momentum ◽  
Performance Deterioration ◽  
And Performance

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.

scholarly journals Surface and subsurface contributions to the build-up of forces on bed particles

2018 ◽  
Vol 851 ◽  
pp. 558-572 ◽  
Author(s):  
Alessandro Leonardi ◽  
D. Pokrajac ◽  
F. Roman ◽  
F. Zanello ◽  
V. Armenio
Keyword(s):  
Mutual Influence ◽  
Subsurface Flow ◽  
Porous Wall ◽  
Industrial Applications ◽  
Solid Particles ◽  
Free Flow ◽  
Spherical Particles ◽  
Large Eddy ◽  
Lift Forces ◽  
Surface And Subsurface Flow

In nature and in many industrial applications, the boundary of a channel flow is made of solid particles which form a porous wall, so that there is a mutual influence between the free flow and the subsurface flow developing inside the pores. While the influence of the porous wall on the free flow has been well studied, less well characterized is the subsurface flow, due to the practical difficulties in gathering information in the small spaces given by the pores. It is also not clear whether the subsurface flow can host turbulent events able to contribute significantly to the build-up of forces on the particles, potentially leading to their dislodgement. Through large eddy simulations, we investigate the interface between a free flow and a bed composed of spherical particles in a cubic arrangement. The communication between surface and subsurface flow is in this case enhanced, with relatively strong turbulent events happening also inside the pores. After comparing the simulation results with a previous experimental work from a similar setting, the forces experienced by the boundary particles are analysed. While it remains true that the lift forces are largely dependent on the structure of the free flow, turbulence inside the pores can also give a significant contribution. Pressure inside the pores is weakly correlated to the pressure in the free flow, and strong peaks above and below a particle can happen independently. Ignoring the porous layer below the particle from the computations leads then in this case to an underestimation of the lift forces.

Effect of Stress Wave Scattering at the Liquid-Particle Interface on Viscosity Calculation of Nanocolloidal Dispersions

2008 ◽  
Author(s):  
Tao Wang ◽  
Xinwei Wang ◽  
Haiping Hong ◽  
Zhongyang Luo ◽  
Kefa Cen
Keyword(s):  
Particle Size ◽  
Autocorrelation Function ◽  
Stress Wave ◽  
Wave Scattering ◽  
Volume Fraction ◽  
Solid Particles ◽  
Spherical Particles ◽  
Computational Domain ◽  
Liquid Particle ◽  
Pressure Tensor

In this work, extensive equilibrium molecular dynamics simulations are conducted to study the shear viscosity of nanocolloidal dispersion. Strong oscillation of the pressure tensor autocorrelation function is observed. The computational domain contains solvent of liquid argon at 143.4 K and spherical particles with volume fraction of 3%. By studying the effect of the particle size, particle density, and acoustic impedance, it is found for the first time that the stress wave scattering/reflecting at the liquid-particle interface due to acoustic mismatch plays a critical important role in the oscillation of pressure tensor autocorrelation function. The Brownian motion/vibration of solid particles is considered to have little effect on the oscillation of pressure tensor autocorrelation function curve except the frequency. And when the particle size is comparable with the wavelength of stress wave, the diffraction of stress wave happens at the interface that will also weaken the oscillation of pressure tensor autocorrelation function.

Design of Low Power Track and Hold Circuit Based on Two Stage Structure

2008 ◽  
Vol E91-C (6) ◽  
pp. 894-902
Author(s):  
T. SATO ◽  
I. MATSUMOTO ◽  
S. TAKAGI ◽  
N. FUJII
Keyword(s):  
Low Power ◽  
Stage Structure ◽  
Two Stage

Non-Spheric Colloidal Suspensions in Three-Dimensional Space

1997 ◽  
Vol 08 (04) ◽  
pp. 985-997 ◽  
Author(s):  
Dewei Qi
Keyword(s):  
Reynolds Number ◽  
Dimensional Space ◽  
Low Reynolds Number ◽  
Paper Industry ◽  
Three Dimensional ◽  
Colloidal Suspensions ◽  
Solid Particles ◽  
Spherical Particles ◽  
Dynamic Simulations ◽  
Low Reynolds

The translation and rotation of non-spherical particles, such as ellipsoidal, cylindric or disk-like pigment particles, in a Couette flow system similar to a blade coating system in the paper industry6 have been successfully simulated by using the lattice-Boltzmann method combined with Newtonian dynamic simulations. Hydrodynamic forces and torques are obtained by the use of boundary conditions which match the moving surface of solid particles. Then Euler equations have been integrated to include three-dimensional rotations of the suspensions by using four quaternion parameters as generalized coordinates. The three-dimensional rotations have been clearly observed. Consequently, the motion of the particles suspended in fluids of both low-Reynolds-number and finite-Reynolds-number, up to several hundreds, has been studied. It appears that the 3D translation and rotation of the non-spherical particles are more clearly observed in a high-Reynolds-number fluid than in a low-Reynolds-number fluid.

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