Use Of Viscosity Research Articles

Dimensionless argument: a narrow grain size range near 2 mm plays a special role in river sediment transport and morphodynamics

Abstract. The grain size 2 mm is the conventional border between sand and gravel. This size is used extensively, and generally without much physical justification, to discriminate between such features as sedimentary deposit type (clast-supported versus matrix-supported), river type (gravel bed versus sand bed), and sediment transport relation (gravel versus sand). Here we inquire as to whether this 2 mm boundary is simply a social construct upon which the research community has decided to agree or whether there is some underlying physics. We use dimensionless arguments to show the following for typical conditions on Earth, i.e., natural clasts (e.g., granitic or limestone) in 20 ∘C water. As grain size ranges from 1 to 5 mm (a narrow band including 2 mm), sediment suspension becomes vanishingly small at normal flood conditions in alluvial rivers. We refer to this range as pea gravel. We further show that bedload movement of a clast in the pea gravel range with, for example, a size of 4 mm moving over a bed of 0.4 mm particles has an enhanced relative mobility compared to a clast with a size of 40 mm moving over a bed of the same 4 mm particles. With this in mind, we use 2 mm here as shorthand for the narrow pea gravel range of 1–5 mm over which transport behavior is distinct from both coarser and finer material. The use of viscosity allows the delineation of a generalized dimensionless bed grain size discriminator between “sand-like” and “gravel-like” rivers. The discriminator is applicable to sediment transport on Titan (ice clasts in flowing methane/ethane liquid at reduced gravity) and Mars (mafic clasts in flowing water at reduced gravity), as well as Earth.

Kinematic viscosity of liquid media and providing metrological observability of experimental results

The subject of this study is to explore modern methods for control of dynamic and kinematic viscosity of liquid media, the state of its metrological support in the republic as well as to see findings from the experiments to ensure metrological control in the International System of Units. The results from this study are found relevant for wide use in agricultural and food products, biologically active additives in assessing quality and safety, metrology. It is also considered relevant in connection with the wide use of viscosity measuring tools in the oil- and fuel industry, medicine, cosmetology, geological and construction and other industries, to evaluate the quality and safety of products, control technological processes at production sites. Scientific and practical recommendations and decisions on improvement of scientific, technical, organizational and regulatory framework of metrological provision of viscometers in the field of ensuring uniformity of measurements and its practical solutions. The findings from the study can be applied with metrological services. Based on the results of the research, metrological examination of various scientific, theoretical and functional viscometers, final conclusions were developed.

SUYUQ MUHTATILARNING KINEMATIK YOQTISHLIGINI O‘LCHISHNING ZAMONAVIY USULLARI VA EXPERIMENTAL NATIJALARNING METROLOGIK KUSHABLIGINI TA’MINLASH.

The subject of this study is to explore modern methods for measuring viscosity of liquid media, the state of its metrological support in the republic as well as to see findings from the experiments to ensure metrological control in the International System of Units (SI). The results from this study are found relevant for assessing quality and safety in agricultural and ood products, biologically active additives, and wide use in metrology. It is also considered relevant in connection with the wide use of viscosity measuring tools in the oil- and fuel industry, medicine, cosmetology, geological and construction and other industries, to evaluate the quality and safety of products, control technological processes at production sites. Scientific and practical recommendations and decisions on improvement of scientific, technical, organizational and regulatory framework of metrological provision of viscometers in the field of ensuring uniformity of measurements and its practical solutions. The findings from the study can be applied with metrological services, accredited state and legal entities in the field of ensuring uniformity of measurements. Based on the results of the research, metrological examination of various scientific, theoretical and functional viscometers, conclusions were developed

Optimization of the production of neutral spirit from renewable yam and cassava starch substrates – A practical approach

The devastating impacts of climate change on our environment have led to increased research on mitigating these impacts, including fast-tracking original timeline for introduction and use of electric driven vehicles. Electric driven vehicles are considered the most promising and efficient way of securing the environment. However, research into partial or total replacement of energy derived from fossil fuels with renewable energy from plant materials such as neutral spirits (bioethanol) is ongoing. This study was carried out to further explore yam and cassava (tubers) starches as renewable raw materials for bioethanol production. The optimal processing conditions that will yield maximum neutral spirits from yam and cassava substrates were studied. Yam starch produced highest bioethanol in the range of 538–545 L of alcohol per tonne (LA/t) on a dry weight basis (dwb) than cassava starch that produced 508–513 LA/t when both substrates were processed at 142 °C. In contrast, cassava starch produced higher bioethanol in the range of 508–512 LA/t than yam starch that produced 409–416 LA/t when both substrates were processed at 85 °C. The reduced processing temperature of 85 °C caused huge loss of spirit yield (∼128 LA/t) for yam, but did not affect the spirit yield for cassava starch, thus saving cost (energy) for the industry. The use of viscosity reducing commercial enzymes such as β-glucanase (as practised in cereals processing) would be unnecessary in tuber starches processing to neutral spirits, and will further save costs for the industry.

A review of fresh properties of self-compacting concrete incorporating sugarcane bagasse ash

Self-compacting concrete (SCC) is a new generation concrete having high deformability in the fresh state and the ability to compact by itself without the use of vibrators, thus reducing time and labor. They are widely used nowadays in zones of congested reinforcements in concrete elements and structures. To achieve the necessary performance targets, SCC requires higher use of viscosity modifying agents and superplasticizers, which increase the cost of production significantly. Thereby, studies are being conducted for incorporating the use of agricultural wastes as partial substitutes for cement in SCC production to bring down the usage of the admixtures, along with lowering the cost. Agricultural wastes, such as sugarcane bagasse ash (SBA), a waste generated from the sugar industry, if used as a partial replacement to cement after suitable processing, improve the fresh properties of SCC. The effect of fresh properties of SCC by the addition of SBA, as investigated by different authors is reviewed in this study. Results of slump flow test, V-funnel test, T500, L-box and J-ring test, obtained from the different papers are compiled and optimum content of SBA that has to be used for the required performance is concluded. Slump flow was observed to decrease with increasing SBA content in SCC, due to higher water absorption of the SBA particles, resulting in a more viscous concrete mix. Similarly, V-funnel time increased due to the increased viscosity. An increase was observed in T500, the time required for the slump flow to reach a diameter of 500 mm, as well. Thus, from analysis of the changes in the fresh properties, this literature review has helped us identify that a replacement of 10–15% cement with sugarcane bagasse ash provides desirable results.

Influence of Sporasarcina pasteurii cells on rheological properties of cement paste

Nowadays with the developments in the concrete materials technology, researches started to focus on highly flowable mixes with improved rheological properties. These highly flowable mixes generally require use of viscosity modifying agents (VMAs) to reduce bleeding and segregation. VMAs are water-soluble polymers that can be produced from acrylic polymers and polysaccharide-based biopolymers obtained from cellulose, starch or bacterial fermentation. Through the literature, nopal mucilage, brown algae and bacterial cell walls were proposed as alternatives to these bio-based admixtures. However, these alternatives also require extra processing which results again with a higher unit cost. This paper summarizes the rheological properties of a cement paste including bacterial cells. The main goal of this study was to investigate the influence of Sporasarcina pasteurii (S. pasteurii) cells on viscosity and yield stress of cement-based materials. The bacterial cells were directly incorporated to the mix water and influence of cells on viscosity and yield strength was evaluated by rheological tests. In addition, the influence of bacteria dosage, water to cement ratio (w/c), use of superplasticizers and fly ash on performance of biological VMA were investigated. Our results showed that the apparent viscosity and yield stress of the cement-paste mix were increased with the addition of the microorganisms. Moreover, the provided biological VMA was found to be compatible with the use of fly ash and superplasticizers depending on the w/c of cement paste.

A temperature-history based model for the sticking probability of impacting pulverized coal ash particles

Several investigations have shown that the differences between deposits obtained in oxy-firing and air-firing of coal mainly are due to differences in the flame temperature. Consequently, deposit rate predictions not taking the in-flight history into account are unlikely to be successful. In this paper, a model for predicting the deposit formation propensity of pulverized coal in oxy-fuel and air combustion due to the inertial impaction mechanism is developed and tested. The model builds on the use of viscosity as an indicator of the sticking probability. The composition and amount of the amorphous slag phase in the coal ash are calculated assuming thermodynamic equilibrium. Further, it is assumed that the maximum temperature the ash particle has experienced will control the composition and amount of the amorphous slag phase. As the ash particle impacts the probability to stick is estimated using the viscosity of this melt composition, but with the temperature of particle temperature at the moment of impaction. In the equilibrium calculation no material exchange with the gas phase is assumed. This assumption is based on X-ray diffraction (XRD) investigations of coal ash samples produced in a lab-scale burner simulating oxy-fuel and air combustion. The XRD showed that there was no significant impact on the mineralogy of the coal ash caused by the gas atmosphere. The probability of an ash particle to stick as a function of maximum experienced temperature and impact temperature was evaluated for three coals. For one of the coals a CFD study on particle deposit is done for a 300kWth test facility.

Greener self-compacting concrete using stainless steel reducing slag

This paper presents the results of a study on self-compacting concrete (SCC) made with stainless steel reducing slag (SSRS). Two kinds of SSRS, being different in the surface area (e.g., 1766- and 7970cm2/g), were employed as filler and cement substitution, respectively. A series of six mixing proportions with a change of SSRS-cement ratio replacing ordinary Portland cement (OPC) from 0% to 50% (increment 10%) were developed for experimental work. The workability, observed via slump flow, slump-flow time (T500), V-funnel time, and Box-filling tests, and the setting time test were involved for freshly-mixed SCC. The hardening and durability parameters such as compressive strength, ultrasonic pulse velocity (UPV), rebound hammer (RH), water absorption, electrical resistivity, and sulfate resistance were estimated, accordingly. The testing results indicate that the workability and viscosity can be satisfactory without the use of viscosity modifying agent as usual. The slump flow increased when 20% or less SSRS substituted for OPC; both the T500 and V-funnel flow time are prolonged for SSRS-based mixtures. Moreover, compressive strength is reduced gradually as the SSRS ratio increases; and SCC made with 30% or less SSRS achieves the required strength of Grade 30 concrete. Also, a strength predictive model, modified from the existing one has been successfully proposed (error range of ±5%). In addition, relationships between compressive strength and UPV, RH number, and electrical resistivity have been successfully established with a high degree of correlation. Finally, a replacement ratio of 10% SSRS could provide the highest sulfate resistivity, evaluating by weight-loss test.

Comment on “History, Origins and Prediction of Elastohydrodynamic Friction” by Spikes and Jie

Progress in the classical field of EHL has for decades been paralyzed by the assumption that shear thinning should be indistinguishable from the shear dependence of the viscosity of a liquid heated by viscous dissipation and that the parameters of this simple shear dependence can be obtained from the shape of a friction curve. In the last few years, by abandoning this assumption and employing real viscosity measured with viscometers, there has been revolutionary progress in predicting film thickness and friction. Now, Spikes and Jie conclude that the previous assumption has as much merit as the use of viscosity measured in viscometers. This suggestion may be popular among those who wish to ignore viscometer measurements in favor of extracting properties from friction curves. However, within the subject article, there are numerous misstatements of fact and misrepresentations by omission, and the recent progress using real viscosity is not acknowledged. The debate has degenerated into a friction curve fitting competition which is not helpful. The great progress of the last few years would not have been possible using the concepts and methods espoused in this article.

Asphalt Binder Contribution to Mixture Workability and Application of Asphalt Lubricity Test to Estimate Compactability Temperatures for Warm-Mix Asphalt

The disconnect between estimated compaction temperatures on the basis of viscosity and behavior observed in laboratory- and field-compacted mixes indicates that the sole use of viscosity is insufficient to characterize the role of the asphalt binder in mixture compaction. The asphalt lubricity test was presented as a complement or replacement to viscosity on the basis of the concept that it was necessary to measure the properties of binders in thin films to relate better to compaction of mixes and to detect the effects of warm-mix asphalt (WMA) additives. To assess the value of the asphalt lubricity test, the relative contributions of lubricity, viscosity, and aggregate gradation on mixture workability at different levels of compactive effort were studied with statistical analysis. The mixes included fine and coarse gradations prepared with various conventional and WMA-modified binders, compacted at a range of temperatures representative of those used for WMA. Results indicated that gradation and binder lubricity contributed significantly to mixture workability at conditions of lower temperature, lower density, or both. The effects of viscosity were found to be insignificant. Aggregate gradation was found to be the most influential factor, which indicated that, for some mixes, use of WMA additives was not always necessary to improve laboratory compaction. To support selection of compaction temperatures on the basis of binder properties, a method was presented to apply the asphalt lubricity test to estimate minimum WMA compaction temperatures.

Use of Viscosity to Probe the Interaction of Anionic Surfactants with a Coagulant Protein from Moringa oleifera Seeds

The intrinsic viscosity of the coagulant protein was evaluated from the flow times of the protein solutions through a capillary viscometer, and the results suggested the coagulant protein to be globular. The interactions of the coagulant protein with anionic surfactant sodium dodecyl sulphate (SDS) and sodium dodecyl benzene sulfonate (SDBS) were also investigated by capillary viscometry. We conclude that there is strong protein‐surfactant interaction at very low surfactant concentrations, and the behavior of the anionic surfactants in solutions containing coagulant protein is very similar. The viscometry results of protein‐SDS system are compared with surface tension, fluorescence, and circular dichroism reported earlier. Combining the results of the four studies, the four approaches seem to confirm the same picture of the coagulant protein‐SDS interaction. All the physical quantities when studied as function of surfactant concentration for 0.05% (w/v) protein solution either exhibited a maximum or minimum at a critical SDS concentration.

Lightweight Shotcrete Canoe: Use of Viscosity Modifying Admixture and Acetone as Artificial Paste

This paper presents some of the most interesting steps followed by the Canadian team from Laval University in developing a high tensile strength, lightweight concrete for the construction of their canoe. This mixture was used in 2004 by the Laval University Concrete Canoe Team, which, year after year, participates in an engineering challenge. The objective is to develop a concrete mixture that can be pumped and shot on a male mold using a custom shotcrete technique. The 2004 mix contains acetone to enhance its fluidity and Welan gum to increase its viscosity, thus preventing segregation.

Kinetics and mechanisms of crystal growth and diffusion in a glass-forming liquid

Extensive data on the viscosity, covering 15 orders of magnitude, and crystal growth rate, covering seven orders of magnitude, of liquid diopside (CaO.MgO.2SiO(2)) were collected in a wide range of undercoolings from 1.10T(g) to 0.99T(m) (T(g) is the glass transition temperature and T(m) the melting point). The raw growth rate data were corrected for the increased interfacial temperature produced by the heat released during crystallization. A detailed analysis confirms that growth mediated by screw dislocations reasonably explain the experimental data in these wide ranges of temperatures and growth rates. Effective diffusion coefficients were calculated from crystal growth rates and from viscosity, and were then compared with measured self-diffusion coefficients of silicon and oxygen in diopside melt. The results show that oxygen and silicon control the diffusion dynamics involved in crystal growth and viscous flow. This study not only unveils the transport mechanism in this complex liquid, but also validates the use of viscosity (through the Stokes-Einstein or the Eyring equations) to account for the kinetic term of the crystal growth expression in a wide range of temperatures.

Centrate viscosity for continuous monitoring of polymer feed in dewatering applications

The researchers have previously documented that minimum centrate or filtrate viscosity using batch measurement indicates the optimum polymer dose as determined by capillary suction time (CST) and solids recovery. This paper describes research conducted to test the use of continuous centrate viscosity measurements for polymer dose monitoring in the biosolids dewatering process. Initial results indicate that liquid stream viscosity must be measured on-site since filtrate samples in the overdosing range decrease in viscosity over several hours following sampling. A sensitive viscometer is required for continuous monitoring since the observed viscosity range is from 1 to 3 centipoise (cP). An international search for viscometer vendors showed that two types of viscometers could be used for this purpose: rotational and vibrational. Only data from rotational type viscometers were obtained for this paper. The viscometer was installed to continuously sample centrate from the centrifugation of anaerobic digested biosolids. Full-scale dose response experiments showed that minimum viscosity correlates with maximum cake solids measurements, and thus such viscometers can be used in monitoring and controlling polymer feed during dewatering. However, several modifications are required for such viscometers to withstand the demanding conditions in wastewater treatment plants. Use of viscosity for control of polymer dose requires use of a minimum value, necessitating a complex control algorithm.

Use of Viscosity in Qualitative Analysis

There are many examples of undergraduate laboratory experiments that illustrate physical properties (i.e., melting point, boiling point, refractive index, density). There are relatively few examples of the use of viscometry in the freshman and sophomore laboratories. Moreover, the use of viscometry is usually treated in the same fashion as melting point determinations (comparison of the experimental viscosity to the literature value.)

Studies of mango processing

SummaryAn experimental thin layer drier is described for evaluating foam‐mat drying characteristics. Polyglyceryl stearate was found to be the most effective foaming agent for Alphonso mango puree. A stable mango foam could be prepared using this surfactant without prior concentration of the puree or the use of viscosity increasing additives. the dependence of the drying rate on temperature, foaming agent concentration and air flow rate is reported. A readily re‐hydrateable powder of 2% moisture content could be produced by drying at 70°C for 20 min. This drying rate compares favourably with earlier studies of the foam‐mat drying of citrus concentrate. the vitamin C content of the puree was decreased by 80% during foam‐mat drying, and this powder was less acceptable than a product obtained by spray‐drying.

Solvation effects and reactivity of free pyridine residues in macromolecules of poly-4-vinylpyridine derivatives

Water-soluble derivatives of poly-4-vinylpyridine (PVP) were prepared by means of quaternization of PVP with ethyl bromide, butyl bromide, hexyl-bromide and bromacetic acid. In addition, hydrolysis of p-nitrophenylacetate (NPA) and 3-nitro-4-acetoxybenzoic acid (NABA) catalyzed by these polymers and 4-ethylpyridine as analogue were studied spectrophotometrically both in water and alcohol-water mixtures at 25° and pH 7·8. The second-order rate of NPA hydrolysis ( K t ) was independent of the length of alkyl groups and the salt concentration. While an increase of the degree of quaternization (β) for PVP derivatives resulted in a reduction of the value of K i in water, in 37–50 vol per cent alcohol-water there was the opposite effect. At large values of β, K i did not depend on the content of ethanol. The bell-shaped dependence of K i on β was shown in the case of amionic NABA. The value of K i proved to be very sensitive to both the nature of salt and the salt concentration in aqueous solution. The use of viscosity, turbidimetry and potentiometry for studying these polymers allowed the role of the quaternized pyridine residue to be elucidated. The peculiarities of the kinetic behaviour of the free basic group were explained by the hydrophilic nature of the quaternized PVP changing as the degree of quaternization is increased so causing an exclusion of the substrate molecules from the polyion.

A viscometric technique for determining the layer thickness of polymer adsorbed on titanium dioxide

A simple viscometric method for measuring the adsorbed layer thickness of polymers on nonspherical particles is proposed. With the use of viscosities at infinite shear rate the effects of flocculation are eliminated and an empirical equation relating phase volume with viscosity is obtained. By use of this equation immobilized polymer thicknesses at the solid/liquid interface have been calculated and related to polymer structure.

Correlating Diffusion Coefficients in Binary Gas Systems. Use of Viscosities in a New Equation and Nomogram

Correlating Diffusion Coefficients in Binary Gas Systems. Use of Viscosities in a New Equation and Nomogram