Liquid Viscosity Research Articles

Rayleigh wave propagation in an initially stressed orthotropic elastic solid half-space lying under inviscid liquid and viscous liquid layers

PurposeThe purpose of this article is the propagation of Rayleigh waves in a homogeneous, isotropic, initially stressed orthotropic elastic solid half-space lying under a homogeneous, viscous, inviscid liquid layer of finite thickness.Design/methodology/approachIn the presence of both viscous and inviscid liquids, it derives the phase velocity, initial stress, and wave number-dependent frequency equation for an orthotropic elastic solid. With the help of the MATLAB program, the thickness effects of liquid layers, initial stress, and viscosity on the phase velocity and attenuation coefficient of the Rayleigh wave are explained for a particular model.FindingsThe phase velocity-dependent dispersion relation of Rayleigh waves at the interface of viscous liquid and solid half-space is a function of initial stress and wave number. Rayleigh waves along the free surface of an orthotropic elastic half-space are also derived as a particular case. The classical results of an inviscid liquid are achieved when the thickness of a viscous liquid approaches zero. Well-known classical results for initially stressed orthotropic elastic solids were also derived.Originality/valueSo far, many researchers have looked into the propagation of surface waves at the interfaces of solid–inviscid liquid, solid–solid, and multilayer interfaces. But in this article, the dispersion behavior of Rayleigh wave propagation in an initially stressed homogeneous orthotropic elastic solid half-space under a double layer of viscous liquid and inviscid liquid is studied.

Electromagnetic penetrometer for high viscosity measurement using a new displacement sensor

In this article, we present an effective device for measuring the high viscosity of Newtonian liquids using a cylindrical penetrometer. The technique relies on monitoring the temporal evolution of penetration depth. Penetration depth is accurately determined by employing a novel electromagnetic micrometric displacement sensor, which is recorded and processed via a National Instruments DAQ card and a custom LabVIEW® program. The introduction of this new electromagnetic displacement sensor, characterized by its high accuracy and its stability, is imperative to ensure reliable measurements of high viscosity. This sensor enables direct, precise, and dependable digital depth of penetration readings. We validated this device by measuring the viscosity of Maltitol as a function of temperature, and the results demonstrate reasonable agreement with values found in the literature.

OPTIMIZATION OF LIQUIDSOAP FORMULATION

The quality of liquid soap for washing hands depends on its chemical composition, and it is evaluated by the physicochemical and functional characteristics of that product. The aim of the work is to prepare different series of liquid soap formulations by varying the concentrations of anionic and amphoteric surfactantsand sodium chloride, and to optimize the formulation. The effects of the optimization were evaluated based on the results of the analysis of the physico-chemical parameters of the prepared formulations, such as density, viscosity, surface tension and critical concentration of micelles. As amphoteric and anionic surfactant concentrations in liquid soap increase, density and viscosity values increase. The value of the surface tension decreases with the increase in the concentration of the surfactants present, with the amphoteric surfactant making a greater contribution to the decrease. Regardless of certain advantages that the anionic surfactant shows in relation to the amphoteric one, the best characteristics of the liquid soap are shown by the formulation thatcontains a combination of both used surfactants. The addition of NaCl to the liquid soap formulation has multiple significance, but also a different effect on the physical and chemical characteristics at lower and higher concentrations. Functional and some physico-chemical characteristics of liquid hand washing soap depend on the pH value of the formulation. As the pH value increases, the surface tension and CMC increase to certain values, so pH=5.5 is taken as the optimal pH value of liquid soap, as a compromise between the values of the measured characteristics and the pH value of human skin. This research showed that the formulation containing 5.4w/w%anionic surfactant, 1w/w%amphoteric surfactant and 4w/w% NaCl represents the optimal liquid soap formulation. KEYWORDS:liquid soap; content of liquid soap; surfactants; electrolyte in liquid soap; characteristics of liquid soap; optimization of formulation

Interfacial and mass transport phenomena in the tri-ethylene glycol-methane system at process conditions of natural gas dehydration

AbstractUnderstanding the phase and interphase behavior at equilibrium and during the mass transfer between two adjacent fluid phases is relevant for optimizing and designing efficient separation processes. This study experimentally investigates the interfacial and transport behavior of systems comprising tri-ethylene glycol (TEG) and methane (CH4) under conditions relevant to the gas dehydration process. A comprehensive review of the interfacial tension (IFT) and diffusivity of systems involving non-polar and polar compounds at elevated pressures was studied. However, a research gap exists, particularly concerning the interfacial tension of systems involving TEG, TEG + water, and different types of gases as well as the diffusivity of CH4 in TEG. To address this gap, this study presents new data on mixture densities, interfacial tension, and drop volumes of TEG and TEG + water in CH4 and CH4 + CO2 mixtures at temperatures ranging from 20 to 50 °C and pressures up to 250 bar using the oscillating U-tube and pendant drop methods, respectively. Additionally, time-dependent fluid mixture densities and TEG droplet volumetric expansion, coupled with an analytical approach for the binary diffusion were applied to determine the CH4 solubility and diffusivity in TEG. The results show that IFT and drop volume of TEG and TEG + water in CH4 and CH4 + CO2 mixtures decrease with increasing pressure. The presence of water increases the IFT of TEG-CH4 up to $$\sim$$ ∼ 5mN/m, while CO2 reduces it by $$\sim$$ ∼ 2mN/m. Interestingly, the IFT and drop volume of TEG-CH4 show no significant change at elevated pressures when temperatures rise from 20 to 50 °C. IFT remains relatively constant over time at moderate pressures but decreases by $$\sim$$ ∼ 3mN/m at an elevated pressure of 150 bar, suggesting methane solubilization into TEG to have a significant influence which is confirmed by TEG drop volume expansion. The diffusivity of CH4 in TEG at 150 bar and 50 °C is determined to be in the range of 10–10 m2/s, which is in agreement with the diffusivity of CH4 in liquids of similar viscosity, i.e. according correlations may be applied as good engineering practice. To the best of our knowledge, there is no such comprehensive work on the properties of fluid mixtures relevant in gas dehydration processes published up to date.

Thermophysical Properties of the Hydrogen Carrier System Based on Aqueous Solutions of Isopropanol or Acetone

One concept for the safe storage and transport of molecular hydrogen (H2) is the use of hydrogen carrier systems which can bind and release hydrogen in repeating cycles. In this context, the liquid system based on isopropanol and its dehydrogenated counterpart acetone is particularly interesting for applications in direct isopropanol fuel cells that are operated with an excess of water. For a comprehensive characterization of diluted aqueous solutions of isopropanol or acetone with technically relevant solute amount fractions between 0.02 and 0.08, their liquid density, liquid viscosity, and interfacial tension were investigated using various light scattering and conventional techniques as well as equilibrium molecular dynamics (EMD) simulations between (283 and 403) K. Polarization-difference Raman spectroscopy (PDRS) was used to monitor the liquid-phase composition during surface light scattering (SLS) experiments on viscosity and interfacial tension. For comparison purposes and to expand the database, capillary viscometry and dynamic light scattering (DLS) from bulk fluids with dispersed particles were also applied to determine the viscosity while the pendant-drop (PD) method allowed access to the interfacial tension. By adding isopropanol or acetone to water, density and, in particular, interfacial tension decrease significantly, while viscosity shows a pronounced increase. The behavior of viscosity and interfacial tension is closely related to the strong hydrogen bonding between the unlike mixture components and the pronounced enrichment of both solutes at the vapor–liquid interface, as revealed by EMD simulations. For an aqueous solution with an isopropanol amount fraction of 0.04, minor variations in interfacial tension and viscosity were found in the presence of pressurized H2 up to 7.5 MPa. Overall, the results from this study contribute to an extended database for diluted aqueous solutions of isopropanol or acetone, especially at temperatures above 323 K.

Preparation and properties of lightweight aluminum silicate-based fibrous ceramic membranes with different binder contents for high-temperature dust removal

Fibrous ceramic membranes are widely regarded as ideal hot-gas filtration media due to their unique three-dimensional network structure. In this work, deionized water and sodium lignosulfonate (NaLS) were respectively introduced into the preparation of fibrous ceramic membranes, with aluminum silicate fibers used as the matrix skeleton and silica sol used as the high-temperature binder. Their effects on the binder content, morphology, structural parameters, and mechanical properties were investigated and compared, and then the application performance of the preferred sample was evaluated. The results indicated that the addition of both significantly reduced the binder content, resulting in decreased bulk density and increased apparent porosity. Notably, compared to the addition of water, the addition of NaLS effectively preserved the binder content at the junctions between fibers so that the flexural strength and stiffness were barely affected, which benefits from the decrease in the viscosity of the binder liquid under the action of electrostatic repulsion and steric hindrance. Moreover, the preferred prepared fibrous ceramic membrane exhibited high-performance characteristics, such as superior thermal shock resistance, low pressure drop, and high filtration efficiency and pulse-jet cleaning efficiency, thereby offering considerable prospects for practical applications.

Characteristics of Particle-Wet Wall Impact Damage: Effects of Liquid Film Parameters

Particle impact damage significantly affects the safe and stable operation of energy and chemical process equipment. During particle transportation, a liquid film may form on the wall, influencing the damage mechanism caused by particle effect. This study investigates the effects of liquid film parameters, specifically viscosity and thickness, on wall damage. Hydroxypropyl Methylcellulose (HPMC) solution was applied as a liquid film, and the effect of the liquid film's viscosity and thickness was examined through impact damage experiments using a particle (45 steel) and a wall (1060 aluminum alloy) with the liquid film. Results indicate that the presence of a liquid film can inhibit wall damage. Increased liquid film viscosity and thickness reduce wall damage, but they affect the turning points of damage characteristic parameters differently concerning impact angle and velocity. Finally, the study establishes correlation between dry and wet impact by introducing the effect coefficient of liquid film. This reveals the alteration rules of the influence coefficient and proposes a wet impact damage model, providing a reference for the damage prediction in process equipment.

Preparation of porous Si3N4 ceramics with excellent mechanical properties:effect of the grain growth mechanism on microstructure evolution

In recent years, porous Si3N4 ceramics have been recognized as the most promising materials for radomes. In this study, porous Si3N4 ceramics with excellent mechanical properties have been successfully prepared by adding 2 wt% Lu2O3, of which the effect of sintering temperature on the grain growth mechanism is investigated for microstructure tailoring. When sintered at 1720°C, the lower liquid viscosity allows the grain growth rate to match with dissolution-precipitation process. Through this process, the grains further grew together to form a more homogeneous rod-like structure, resulting in a more concentrated aspect ratio and particle size distribution. In addition, the grains along the c-axis grew faster due to the Lu3+ ions, resulting in a higher aspect ratio. However, when further increased to 1750°C, the viscosity of the liquid decreases significantly, leading to the precipitation of a large number of β-Si3N4 nuclei. Due to the combined effect of the steric hindrance and the liquid phase mainly distributed at the ends of the grains, a short and thick morphology with a thick center and fine ends is formed, which is unfavorable to the bending strength. Therefore, when the porosity of the sample at 1720°C is 64.5%, the bending strength can still reach 162 MPa with a structure factor of 2.82.

Investigating the Effect of the Yellow Chlorophyll on the Characteristics of Liquid Polyethylene Glycol for Liquid Electrolyte Solar Cells

In this study, polyethylene glycol (PEG) and natural dye were employed to make the liquid electrolyte media for solar cells. To prepare varied amounts of dye, the yellow dye of the flowers was extracted using diluted ethanol via ionized water. To produce a constant concentration of all polymer liquids, 10g of PEG dissolves in 1000 ml of solvents including: (di-water, dilute dye, and concentrated dye) individually. The viscosity of solutions was determined using an Ostwald viscometer at various temperatures. Optical parameters such as transmittance, absorbance, and indirect energy gap were investigated utilizing the ultraviolet spectrum. The results reveal that increasing the temperature causes the viscosity decreases and the solar cell efficiency increases. When the dye concentration is increased, the absorbance and absorption coefficient increase, while the transmittance decreases. After adding the concentrated dye, the energy gap of liquid PEG reduces from 1.4 eV to 0.6 eV. PEG with concentrated dye, on the other hand, is the best sample based on the energy gap value. As a result, four concentrations of PEG liquid were prepared: (0.02, 0.025, and 0.03) w/v concentrations, followed by the addition of the concentration dye in the same quantity for each concentration of PEG liquid. Four prepared liquids were tested for viscosity. The results showed that the viscosity of PEG + concentrated dye decreased as the PEG concentration was increased. When the concentration of PEG solution without dye is increased, the viscosity of PEG liquids increases.

Comprehensive Theoretical Formulation and Numerical Simulation of the Internal Flow in Pressure-Swirl Atomizers Type Screw-Conveyer

The present work shows the development of a comprehensive theoretical formulation for its application in the study of the internal flow of pressure-swirl atomizers with helical channels: “screw-conveyer”, which are characterized by presenting in their inlet channels, an angle of incidence or helix angle ψ. This angle originates a trigonometric factor (cosψ) that must be considered in the geometrical characteristics parameter of pressure-swirl atomizer (Ah), which consequently involves other geometric parameters, such as the annular section coefficient (φ), discharge coefficient (Cd), spray angle (2α), etc., being relevant in the internal flow study and design of the pressure-swirl atomizers type screw-conveyer. This theoretical formulation integrates an internal ideal flow model (Abramovich theory) with a model that considers the influence of the liquid viscosity (Kliachko theory) and hydraulic resistance of Idelchik. For the validation of this theoretical formulation, numerical simulation was used, considering the commercial software Ansys Fluent 2023 R2 furthermore, hexahedral meshes were generated with the ICEM CFD software 2023, for four cases of helix angle ψ (15°, 30°, 45° and 60°), with application of the RNG k-ε turbulence model and VOF multiphase model (volume of fluid) for the location of the liquid-gas interface and spray angle visualization.

Liquid Viscosity and Surface Tension of Cyclohexane Between 280 and 473 K by Surface Light Scattering

The present study provides experimental data for the liquid viscosity and surface tension of cyclohexane at or close to saturation conditions by surface light scattering between (280 and 473) K. By applying the hydrodynamic theory for surface fluctuations at the vapor–liquid phase boundary, which could be verified experimentally, the liquid viscosity and surface tension were determined simultaneously at macroscopic thermodynamic equilibrium with average relative expanded (k = 2) uncertainties of Ur(η′) = 0.020 and Ur(σ) = 0.012. For both properties, the present measurement results agree well with reference values in the literature which are restricted to a maximum temperature of 393 K for viscosity and 337 K for surface tension. The experimental results from this work contribute to an improved database for the viscosity and surface tension of cyclohexane over a wide temperature range from a temperature close to the melting point up to 473 K.

Coupling cubic equations of state with the concept of entropy scaling to model the viscosity of ionic liquids

This short paper investigates the applicability of our previously developed entropy scaling model to pure ionic liquids and concludes that it can be used without any modification and leads to very satisfactory results when coupled with the Peng-Robinson or Soave-Redlich-Kwong cubic equations of state. For the considered ionic liquids, the average deviations between calculated and experimental viscosities were found to be around 4.6 and 5.8% for the two cubic equations of state, respectively.

An Adaptive Parameter Optimization Deep Learning Model for Energetic Liquid Vision Recognition Based on Feedback Mechanism.

The precise detection of liquid flow and viscosity is a crucial challenge in industrial processes and environmental monitoring due to the variety of liquid samples and the complex reflective properties of energetic liquids. Traditional methods often struggle to maintain accuracy under such conditions. This study addresses the complexity arising from sample diversity and the reflective properties of energetic liquids by introducing a novel model based on computer vision and deep learning. We propose the DBN-AGS-FLSS, an integrated deep learning model for high-precision, real-time liquid surface pointer detection. The model combines Deep Belief Networks (DBN), Feedback Least-Squares SVM classifiers (FLSS), and Adaptive Genetic Selectors (AGS). Enhanced by bilateral filtering and adaptive contrast enhancement algorithms, the model significantly improves image clarity and detection accuracy. The use of a feedback mechanism for reverse judgment dynamically optimizes model parameters, enhancing system accuracy and robustness. The model achieved an accuracy, precision, F1 score, and recall of 99.37%, 99.36%, 99.16%, and 99.36%, respectively, with an inference speed of only 1.5 ms/frame. Experimental results demonstrate the model's superior performance across various complex detection scenarios, validating its practicality and reliability. This study opens new avenues for industrial applications, especially in real-time monitoring and automated systems, and provides valuable reference for future advancements in computer vision-based detection technologies.

Finite element simulations of quartz crystal microbalances (QCM): from Sauerbrey to fractional viscoelasticity under water

2D finite element simulations are performed on QCM working in the thickness-shear mode and loaded with different homogeneous films. They include a purely elastic film, a viscoelastic Maxwellian liquid, viscoelastic-Voigt solid, and the fractional viscoelastic (power-law) version of each case. Unlike single-relaxation kind models, fractional viscoelasticity considers the relaxation-time spectrum often found in polymeric materials. The films are tested in air or covered with liquids of different viscosities. Two substrate thicknesses are tested: 100 nm and 500 nm, the latter being close to the condition that promotes the resonance of the adsorbed film. In all cases the simulations are compared with small-load approximation theory (SLA). The 100 nm films follow the theory closely, although significant deviations of the SLA are observed as the overtone number n increases, even in purely elastic films. We also show that it is possible to identify the viscoelastic ‘fingerprint’ of the 100 nm films in air using raw data and Sauerbrey’s equivalent thickness obtained with the QCM in the 3 < n < 13 range. These numerical data are validated by experimental measurements of crosslinked polydimethylsiloxane films with thicknesses ∼150 nm. In contrast, the 500 nm films deviate notoriously from the SLA, for all viscoelastic models and overtones, with the largest deviation observed in the elastic film. When a liquid layer covers the QCM without an adsorbed film, the only overtone that numerically reproduces the theoretical value is the fundamental, n = 1. For n > 1, strong coupling between the solid and liquid is detected, and the original vibration modes of the crystal are altered by the presence of the liquid. Finally, the numerical simulations suggest that it is possible to detect whether a viscoelastic film is formed under a liquid layer using only the information from n = 1. In these film/liquid systems we also observe the so-called missing-mass effect, although the theory and simulations exhibit different levels of impact of such effect when the liquid viscosity is high.

Prediction and Simulation of Biodiesel Combustion in Diesel Engines: Evaluating Physicochemical Properties, Performance, and Emissions

Environmental and energy sustainability concerns have catalyzed a global transition toward renewable biofuel alternatives. Among these, biodiesel stands out as a promising substitute for conventional diesel in compression-ignition engines, providing compatibility without requiring modifications to engine design. A comprehensive understanding of biodiesel’s physical properties is crucial for accurately modeling fuel spray, atomization, combustion, and emissions in diesel engines. This study focuses on predicting the physical properties of PODL20 and EB100, including liquid viscosity, density, vapor pressure, latent heat of vaporization, thermal conductivity, gas diffusion coefficients, and surface tension, all integrated into the CONVERGE CFD fuel library for improved combustion simulations. Subsequently, numerical simulations were conducted using the predicted properties of the biodiesels, validated by experimental in-cylinder pressure data. The prediction models demonstrated excellent alignment with the experimental results, confirming their accuracy in simulating spray dynamics, combustion processes, turbulence, ignition, and emissions. Notably, significant improvements in key combustion parameters, such as cylinder pressure and heat release rate, were recorded with the use of biodiesels. Specifically, the heat release rates for PODL20 and EB100 reached 165.74 J/CA and 140.08 J/CA, respectively, compared to 60.2 J/CA for conventional diesel fuel. Furthermore, when evaluating both soot and NOx emissions, EB100 displayed a more balanced performance, achieving a significant reduction in soot emissions of 34.21% alongside a moderate increase in NOx emissions of 45.5% compared to diesel fuel. In comparison to PODL20, reductions of 20.4% in soot emissions and 3% in NOx emissions were also noted.

Shearing Liquids of Unequal Viscosity: Can Mixing be Independent of Stirring Rate at a Large Viscosity Ratio?

Mixing liquids with unequal viscosity involves complex flows and a nontrivial diffusive feedback. As an insightful reference case, we study the deformation of a spherical blob with viscosity λη, sheared in a miscible bath with viscosity η. Experiments resolve the transition from unbounded stretching, at low λ, to rollinglike motion, at large λ. In between the blob is transiently substretched before destabilizing into swirling structures. Exact solutions of the flow recover all three regimes and predict a transition ratio λ_{c}≃3.975. We discuss the dramatic impact of the flow transition on mixing and propose scaling laws for the blob mixing time in the limit of large Péclet numbers, suggesting mixing could be independent of shear rate at large λ.

The development of undercut and bulge on a solidified surface

Abstract This study numerically investigates the development of undercuts and bulges parallel to the scanning direction on the surface solidified from a thermocapillary molten pool. The analysis considers various parameters, including power-off time, active solute concentration, beam power and radius, surface tension, liquid thermal conductivity, viscosity, and density. The formation and shapes of undercuts and bulges directly impact the yield, fatigue, fracture strength, and stress concentration in the solidified region. Unsteady two-dimensional fluid flow and heat transfer, which drive surface deformation in metals containing surface-active solutes (e.g., iron with sulfur), are solved using COMSOL Multiphase version 5.6. The development of the undercut, bulge, and molten pool is identified in six stages, based on whether the peak temperature is below the melting temperature, between the melting and critical temperatures, or above the critical temperature during heating and power-off periods. The critical temperature, determined as a function of solute content and temperature, leads to inward surface flow in the undercut near the pool edge, while the bulge in the central region can form due to either inward or outward surface flow. The predicted undercut depth and bulge height align well with previous scaling analyses and experimental data from laser polishing. These findings are relevant to various processes, including welding, additive manufacturing, polishing, melting, and solidification.

Performance analysis of shear horizontal one port surface acoustic wave (SAW) resonator for optimal liquid sensing based on finite element method

This paper presents the numerical study using finite element method for optimal liquid sensing performance of one port surface acoustic wave (SAW) resonator. Simulation shows that the extend of IDT-reflector gap can be optimized to contain most of the piezoelectric displacement. Various settings of liquid placement on the mentioned region yield distinct resonant frequency responses of the SAW sensor. For concentrated liquid with higher order of viscosity, magnitude of S-Parameter and phase of the propagating SAW can be applied to sense the liquid solutions. Based on the results, optimal liquid sensing performance of the device can be achieved when liquid droplet sized about 10 % of the aperture is placed in the middle position of the IDT-reflector gap conditioned at 1.5 λ. Using the formulated strategy, the one port SAW device distinguishes well 0 % to 100 % glycerine concentrations compared to limited detection range reported in the previous study. The finding includes equation of liquid turnover viscosity before shift in direction of the changes in S-Parameter measurement. The derived parameters can be set as reference to design the microfludic cell or lab-on-chip based on the one port SAW configuration for optimized liquid sensing performance.

Dynamics of non-Newtonian droplets eccentrically impacting hydrophobic spherical surfaces

In this study, the dynamic behaviors of non-Newtonian fluid droplets with shear-thinning properties eccentrically impacting hydrophobic particle surfaces are investigated through a combination of numerical simulations and experiments. The simulation integrates the dynamic contact angle and a non-Newtonian fluid power-law model within the volume of fluid model framework. The effects of apparent viscosity (η), impact velocity (v0), and dimensionless eccentricity parameter (B) on the dynamic behaviors of non-Newtonian droplets are analyzed. Furthermore, the study offers insight into the progression of pressure distribution, kinetic energy, and liquid viscosity across droplets during the entire impact process. An energy balance analysis, which includes kinetic energy, surface energy, potential energy, and viscous dissipation, is employed to elucidate the fundamental physical mechanisms that govern the dynamics of eccentric impacts of non-Newtonian droplets. Finally, a model (Recr D* = −95.7 + 11 450.6e−B/0.18) is proposed to predict the adhesion or detachment of shear-thinning droplets eccentrically impacting hydrophobic particle surfaces.

Melt viscosity tracks the volcanic and magmatic evolution of the 2021 Tajogaite eruption, La Palma (Canary Islands)

After more than 50 years of repose, on September 19, 2021, a volcanic eruption began at the Cumbre Vieja ridge on La Palma, Canary Islands. The combined effusive and explosive activity generated a > 12 km2 lava flow field with a new cone nearly 200 m higher than pre-eruptive topography and a vast tephra blanket. The immediate impact was locally devastating, destroying nearly 2000 buildings, blocking two main and numerous secondary roads, and inundating high-value agricultural land.The hybrid nature of the eruption and the observed variations in eruption intensity motivated a thorough investigation of bulk liquid viscosity at high temporal resolution. Collection of 82 lava samples was achieved at a near daily resolution over the course of the 85-day-long event (through the end of the eruption on December 13, 2021). All the samples were remelted, and liquid viscosity was measured in a concentric cylinder viscometer from 1500 °C down to incipient crystallization temperatures. These data constitute the highest temporal resolution viscosity dataset obtained for an eruptive sequence to date.A tripartite viscosity pattern is identified at isothermal conditions: 1) during the fissure opening and establishing stage (days 1–20) a linear decrease in melt viscosity occurred; 2) during most of the eruption duration (days 21–70) viscosity was constant and 3) from day 70 until the end of the eruption viscosity increased again. We interpret this pattern as magma being extracted from different parts of the plumbing system over the course of the eruption. Accordingly, we show that viscosity time series can help shed light on some of the complexities of volcanic plumbing system. Additionally, the presented results highlight the monitoring potential of the viscosity assessment approach, specifically in regard to forecasting eruption behavior using direct information about magma mobility and detecting changes in magmatic plumbing system dynamics.