High Viscous Fluid Research Articles

Effects of fluid saturation and viscosity on seismic dispersion characteristics in Berea sandstone

Despite additional availability of laboratory data from water-saturated sandstone at seismic frequencies, measurements of rock samples saturated with high viscous fluids, particularly at partial saturation, are still rare. To quantify the effects of fluid viscosity and saturation levels on seismic dispersion and attenuation characteristics, we conducted two comparative forced-oscillation measurements in partially saturated sandstone with varying fluid viscosity (e.g., water, glycerin) at seismic frequencies (2–400 Hz). The results demonstrate that fluid viscosity and saturation levels substantially influence the dispersion and attenuation characteristics at the measured frequencies. Significant dispersion and attenuation are observed in the presence of a relatively small amount of gas (approximately 6%–8%) for glycerin and water saturation cases but vary in their magnitudes and characteristic frequencies. Specifically, the maximum extensional attenuation (approximately 0.024) occurs at approximately 200 Hz for water-saturated rock at 94% saturation, whereas at approximately 30 Hz with a peak of 0.032 for glycerin-saturated rock at 92% saturation. Based on theoretical modeling analysis, we suggest that mesoscopic fluid flow might be a dominant mechanism accounting for the observed attenuation in partial water or glycerin saturation, while the microscopic (squirt) flow mechanism possibly dominates the fully saturated cases.

Devolatilization of high viscous fluids with high gravity technology

Volatile organic compounds (VOCs) are generally toxic and harmful substances that can cause health and environmental problems. The removal of VOCs from polymers has become a key problem. The effective devolatilization to remove VOCs from high viscous fluids such as polymer is necessary and is of great importance. In this study, the devolatilization effect of a rotating packed bed (RPB) was studied by using polydimethylsiloxane as the viscous fluid and acetone as the VOC. The devolatilization rate and liquid phase volume (KLa) have been evaluated. The results indicated that the optimum conditions were the high-gravity factor of 60, liquid flow rate of 10 L·h−1, and vacuum degree of 0.077 MPa. The dimensionless correlation of KLa was established, and the deviations between predicted and experimental values were less than ±28%. The high-gravity technology will result in lower mass transfer resistance in the devolatilization process, enhance the mass transfer process of acetone, and improve the removal effect of acetone. This work provides a promising path for the removal of volatiles from polymers in combination with high-gravity technology. It can provide the basis for the application of RPB in viscous fluids.

Motion Behaviors of Two Ascending Bubbles in a Wide Range of Viscous Liquid

Foaming devolatilization is a common phenomenon in a process of viscous solution. Bubble growth and motion behaviors depends on the flow conditions and the properties of liquid phase and that is closely related to heat and mass transfer efficiency in devolatilization process. Herein, experimental study of two ascending bubbles in a wide range of viscous fluid were conducted to achieve an understanding of the formation, coalescence and escape. As a supplement and verification, the motion behaviors rising bubbles were also investigated numerically. Results showed that the first bubble generated a tail vortex to affect the next bubble entering the region. The escape time also increased from 0.3 s to 65 s as the fluid viscosity charged from 0.05.Pa · s to 447 Pa · s, and the bubble broke and it could not formed completely with a high viscous fluid in large rate. It was expected the experimental escape time of bubble in different flow rate was in good agreement with the numerical results.

Numerical investigation of viscous fingering in a three-dimensional cubical domain

We perform three-dimensional numerical simulations to understand the role of viscous fingering in sweeping a high-viscous fluid (HVF). These fingers form due to the injection of a low-viscous fluid (LVF) into a porous media containing the high-viscous fluid. We find that the sweeping of HVF depends on different parameters such as the injection velocity (U0) of the LVF, ease of diffusion of the fluid (D), and the logarithmic viscosity ratio of HVF and LVF ℜ. The two-phase Darcy's law module of COMSOL Multiphysics is used to simulate different cases with varying parameters. At high values of U0 and ℜ and lower values of D, the fingers grow non-linearly, resulting in earlier tip splitting of the fingers and breakthrough, further leading to poor sweeping of the HVF. In contrast, the fingers evolve uniformly at low values of U0 and ℜ, resulting in an efficient sweeping of the HVF, while a higher diffusion coefficient leads to a smooth flow with fewer fingers. We also estimate the sweep efficiency and conclude that the parameters U0, D, and ℜ be chosen optimally to minimize the non-linear growth of the fingers to achieve an efficient sweeping of the HVF.

Motility related gene expression of Campylobacter jejuni NCTC 11168 derived from high viscous media.

Flagellation is one of the major virulence factors of Campylobacter jejuni (C. jejuni), enabling bacterial cells to swarm in rather high viscous fluids. The aim of this study was to determine the impact of the surrounding viscosity on the expression of motility related genes of C. jejuni. Therefore, bacterial RNA was extracted from liquid cultures as well as from bacterial cells recovered from the edge and the center of a swarming halo from high viscous media. The expression pattern of selected flagellar and chemotaxis related genes was investigated by RT-PCR. Higher mRNA levels of class 1 and lower levels of class 2 and 3 flagellar assembly genes were detected in cells derived from the edge of a swarming halo than in cells from the center. This indicates different growth states at both locations within the swarming halo. Furthermore, higher mRNA levels for energy taxis and motor complex monomer genes were detected in high viscous media compared to liquid culture, indicating higher demand of energy if C. jejuni cells were cultivated in high viscous media. The impact of the surrounding viscosity should be considered in future studies regarding motility related questions.

Machine learning opens a doorway for microrheology with optical tweezers in living systems

It has been argued that linear microrheology with optical tweezers (MOT) of living systems “is not an option” because of the wide gap between the observation time required to collect statistically valid data and the mutational times of the organisms under study. Here, we have explored modern machine learning (ML) methods to reduce the duration of MOT measurements from tens of minutes down to one second by focusing on the analysis of computer simulated experiments. For the first time in the literature, we explicate the relationship between the required duration of MOT measurements (Tm) and the fluid relative viscosity (ηr) to achieve an uncertainty as low as 1% by means of conventional analytical methods, i.e., Tm≅17ηr3 minutes, thus revealing why conventional MOT measurements commonly underestimate the materials’ viscoelastic properties, especially in the case of high viscous fluids or soft-solids. Finally, by means of real experimental data, we have developed and corroborated an ML algorithm to determine the viscosity of Newtonian fluids from trajectories of only one second in duration, yet capable of returning viscosity values carrying an error as low as ∼0.3% at best, hence opening a doorway for MOT in living systems.

Analysis of cuttings concentration experimental data using exploratory data analysis

Cuttings transportation is a complex phenomenon involving many inter-acting variables. Experimental investigations on cuttings transport are carried out by different research groups for decades and varying findings are reported which points out to the need for a methodical data analysis approach. In the current paper, six experimental datasets (702 observations) are analyzed using exploratory data analysis (EDA) in a two-fold manner – univariate and multivariate analysis. Univariate analysis shows the asymmetry in distribution for each experimental parameter indicating the need for a nonparametric modeling approach. Multivariate analysis shows the interaction of the experimental parameters among themselves and their influence on downhole cuttings concentration (Cc) using 6D scatter plots and correlation coefficients (Kendall's τ). EDA of the current experimental data reveals the following major findings:•Smaller Cc in concentric vertical wells compared to concentric non-vertical wells.•Drilling fluid flow rate is a dominant operational parameter in vertical wellbore cleaning while string rotation (RPM) is dominant in non-vertical wellbore cleaning.•Little impact of RPM in concentric vertical well and negative eccentric deviated/highly deviated well cleaning. However, RPM together with drilling fluid flow rate provides better cleaning of non-vertical wells with positive eccentricity.•RPM has higher influence on cuttings transport in narrow annulus compared to that in wide annulus.•Assuming drilling fluid of sufficient viscosity and drill string rotation present, low viscous fluid under turbulent flow and high viscous fluid under laminar flow provide better hole cleaning. Further, Kendall's τ indicates apparent viscosity playing a more significant role in cleaning deviated wellbores compared to other inclinations for the current dataset.•Drilling fluid flow rate influences the transport of heavier cuttings and larger cuttings more while RPM has higher influence on the transport of lighter cuttings and smaller cuttings.•Better hole cleaning by heavier drilling fluids than that by lighter fluids.

Experimental investigations and 3D simulations by the overset grid method on twin-screw machines in both pump and turbine mode

Twin-screw pumps due to their particular capabilities, offer u nique b enefits in comparison to other types of pumps. They can also recover wasted energy from the fluid system when run in a reversed way, i.e., in turbine mode. In this study, the possibility of benefiting twin-screw machines instead of conventional control valves in order to recover energy is investigated. Flow physics and energy recovery are analyzed experimentally and by 3D flow simulations in both, pump and turbine mode. Pump and turbine characteristics under different operating points are experimentally measured for low and high viscous fluids, i.e., water and oil, respectively. It is observed that for higher viscosity the dependency of volume flow rate on the pressure difference imposed on the pump is reduced. This observation indicates the significant effect of viscosity on the gap flow. Based on a simulation method by means of overset grid technique, unsteady 3D flow simulations with a high grid quality and a high spatial resolution particularly in gap regions in terms of y + < 1 are conducted and results are validated against experiments. The profound assessment of gap flow based on the simulation results shows that for highly viscous fluids such a soil, the rotational speed of spindles as well as the direction of rotation have a significant effect on gap flow characteristics and consequently on the pump and turbine performance. From the experiments, it is clarified that with a lower rotational speed of spindles and a higher pressure difference, a higher amount of energy up to about 50% of the fluid energy in the piping system can be recovered instead of being dissipated by a conventional control valve.

Dynamic wetting characteristics during droplet formation in a microfluidic T-junction

• Dynamic wetting characteristics during droplet formation in a microfluidic T-junction are investigated. • The three-phase contact line dynamics are influenced by the channel wettability and other flow properties. • The dynamic contact angle increases with an increase in Capillary number, static contact angle, and dispersed phase viscosity. • In contrast it decreases with an increase in flow rate ratio and slip length. Droplet formation in a microfluidic T-junction is dominated by the interfacial force arising between the two fluids. The three-phase contact line at the channel wall is affected by the surface energy or the wettability of the channel wall and other hydrodynamic forces. The dynamics of a three-phase contact line can be evaluated in terms of dynamic contact angle, which a moving contact line makes with a wall. The present work investigates the influence of wall hydrophobicity and fluid properties on the three-phase contact angle during droplet formation in a microfluidic T-junction. Experimental and numerical investigations are performed to study the effects of flow properties on the dynamic wetting of the channel during the droplet formation process. A level-set-based numerical model is employed to predict the moving contact line for different operating parameters and wettabilities of channel walls. Further, a simplified analytical model is developed to express the influence of flow parameters on the dynamic wetting behavior of the wall. The interface is more stressed out for a low viscous dispersed fluid, whereas the interface is less affected by a high viscous dispersed phase fluid. During the transient droplet stage, the dynamic contact angle increases with time with the increase in channel wall hydrophobicity. The dynamic contact angle increases with time for a higher static contact angle, and the variation decreases at a lower static contact angle. At the steady-state, the dynamic contact angle increases with the static contact angle and dispersed phase viscosity. In contrast, it decreases with an increase in the flow rate ratio and the slip length. The droplet with a higher length tends to increase the wetting line in the channel wall. The wettability of the channel wall influences the droplet interface along the lateral direction resulting in corner leakage flow, which further affects the dynamic contact angle.

Fabrication of meso sized structures through controlled viscous fingering in Lifting Plate Hele-Shaw Cell with holes and slots

ABSTRACT Lifting plate Hele-Shaw cell involves a high viscous fluid sandwiched between two parallel plates. The low viscosity fluid (air) enters from the periphery when one of the plates is lifted away from another plate. The air penetrates a high viscous fluid at various points from the periphery. This penetration causes the formation of a tree-branch-like structure called viscous fingering. Due to this insertion, sandwiched fluid changes its structure. This structural change is known as instability. The viscous fingers generated through this flow are highly random and unstable. This study presents methods to control the instabilities. The study reports control techniques by providing anisotropies (holes and slots) on any one of the plates. The study further presents the effect of size, position, and the orientation of these holes and slots on the viscous fingering exhaustively. Deployment of these control techniques leads to the emergence of new fabrication techniques with the potential to develop meso-sized finger patterns spontaneously without expensive setup as otherwise required in the lithography process. To demonstrate the capability of this proposed fabrication technique, various net-shaped patterns available in nature are mimicked. These developed miniature patterns can be used in various applications such as micro-mixers, micro-heat exchangers, etc.

CFD modeling of turbulent flow for Non-Newtonian fluids in rough pipes

Non-Newtonian fluids are pumped under laminar and turbulent regimes through pipes in numerous industries. Proper calculation of pressure losses is essential to optimize available horsepower. In actual practice, no pipe surface is smooth. Pipe roughness has significant influence on the pressure loss for turbulent flow. In this study, a mechanistic model is developed to predict pressure losses of Herschel-Bulkley and Power-Law fluids in rough pipes for the turbulent flow regime. A numerical scheme is applied to the proposed model to obtain an approximate solution. The proposed model is separated into two sub-problems in order to obtain a numerical solution. One is solved analytically for the viscous sublayer, which is determined by pipe roughness and the other is solved numerically by the virtue of the central difference approximation along with the frozen non-linear term for the turbulent core region. Moreover, an experimental study is conducted using two different high viscous polymer base fluids with two different concentrations and three different rough pipe diameters. The mechanistic model results are compared with experimental data in this study and presented by Subramanian (1995). Absolute Average Percent Error (AAPE) of 13.3% is calculated for the proposed model compared to experimental measurements.

Seismo-acoustic gliding: An experimental study

The gradual temporal shift of the spectral lines of harmonic seismic and/or acoustic tremor, known as spectral gliding, has been largely documented at different volcanoes worldwide. Despite the clear advantage of the experimental approach in providing direct observation of degassing processes and related elastic radiation, experimental studies on gliding tremor are lacking. Therefore, we investigated different episodes of gliding of acoustic and seismic tremor observed during analogue degassing experiments performed under different conditions of magma viscosity (10-1,000 Pa s), gas flux (5-180×10−3 l/s) and conduit surface roughness (fractal dimension of 2-2.99). Gliding experimental harmonic seismic and acoustic tremor was observed at high gas flux rates and viscosities, mostly associated with an increasing trend and often preceding a major burst. Decreasing secondary sets of harmonic spectral lines were observed in a few cases. Results suggest that gliding episodes are mostly related to the progressive volume variation of shallow interconnected gas pockets. Spectral analyses performed on acoustic signals provided the theoretical length of the resonator that was compared against the temporal evolution of the gas pockets, quantified from video analyses. The similarities between the observed degassing regime and churn-annular flow in high viscous fluids encourage further studies on churn dynamics in volcanic environments.

Numerical simulation of flow pattern for non-Newtonian flow in agitated thin film evaporator

Agitated thin film evaporator (ATFE) is a new type of high-efficiency evaporator where a film is forced to form through a rotating scraper and the high-viscosity non-Newtonian flow materials can be evaporated smoothly. The flow distribution and transmission mechanism of the material in the evaporator directly determine the evaporation efficiency and power consumption of the evaporator. Unlike previous study that was based mainly on Newtonian flow, this paper establishes a three-dimensional computational fluid dynamics model of ATFE for non-Newtonian flow with different viscosities, and systematically probes the flow field distribution characteristics and film forming mechanism in the evaporator. The results show that the flow field distribution characteristics of low-viscosity non-Newtonian flow are similar to those of Newtonian flow, the material can form a uniform and continuous liquid film on the wall; as the viscosity increases, the uniformity and continuity of the liquid film gradually deteriorate. Through studying the flow field distribution and transmission form of the materials, and combining the liquid film distribution, velocity distribution, shear strain rate distribution, and viscosity distribution, it is found that the shear field and viscosity distribution formed by the internal structure and operating state of the evaporator are the key to the good film formation. In addition, it is proposed that the bending of the leading edge of the scraper can assist the spreading of high viscous fluid liquid film, and the best bending angle is explored. This research provides theoretical guidance and basis for the design and application of ATFE.

Effect of anisotropies in formation of viscous fingering in lifting plate Hele-Shaw cell

ABSTRACT This study presents an experimental investigation of viscous fingering formation under anisotropies in Hele-Shaw cell. The lifting plate Hele-Shaw cell employed in this study comprises of two parallel plates firmly positioned one over another with a minuscule gap filled with high viscous fluid, and a low viscous fluid flows through this gap. Two fluids of different viscosity interact in this cell and instabilities are generated due to the viscosity difference. These instabilities need to be suppressed to get controlled and stabilised patterns. Literatures presented these instabilities and explored the various techniques to stabilise them. In this study, a novel strategy consists of use of anisotropy and protrusion on the lower plate of the cell to suppress instabilities is presented. The holes and protrusions explicitly generate the least resistance to the flow of low viscous fluid (air). This results in control flow and guided path for low viscous fluid (air) penetrating into a high viscous fluid. These methods have given excellent control over the instabilities, and beautifully controlled naturally inspired patterns are obtained. Microfractals present in nature, such as leaf venation, honeycomb pattern, are examined and imitated by the proposed method. Experimental results confirm the acceptability of this control strategy.

Development of New Element for Mixing of High and Low Viscous Fluids

Development of New Element for Mixing of High and Low Viscous Fluids

On the generation and evolution of heated vortex rings in viscous fluids

Vortex rings are turbulent coherent structures that are ubiquitous in various application domains ranging from gas turbines to aquatic locomotion. The vortex rings are highly sensitive to a variety of external governing parameters. In this paper, we have quantitatively investigated the topology and formation mechanisms of such rings under the effect of externally modulated temperature, pressure, and amount of fluid injection. Vortex characteristics like translational velocity, peak vorticity, and circulation are analytically predicted along with rigorous experimental corroboration. The experiments are carried out on high viscous fluids with circulation-based vortex Reynolds number varied in the range of 8–100.​ The rings under distinct conditions are generated from a solenoid valve-controlled pipe by varying the externally governed parameters. We have shown that these parameters can be collapsed into a universal variable to provide insights into the vortex roll-up characteristics and variation of energy distribution towards translation and circulation for a given vortex ring.

Effect of viscosity on entropy generation for laminar flow in helical pipes

Entropy generation for fully developed laminar flow in a helical pipe carrying high viscous fluid under constant temperature boundary conditions is investigated analytically. This work focuses on geometrical, fluid, and thermal aspects and their influence on irreversibilities in helical coils. The effect of viscosity on the irreversibilities and its influence on the operating parameters of the helical coil are studied with the second law of thermodynamics. The most commonly used relationships for estimating viscosity change due to temperature are selected for analysis. The entropy generation and avoidable exergy destruction in each case are presented. Bejan number is plotted for varying viscosities under different wall temperatures for both heat transfer to and from the fluid. The thermodynamic potential of improvement based on avoidable and unavoidable exergy destruction concepts showed that the potential of improvement for heating and the cooling condition is considerable for a given operating condition in helical tubes. The selected model for estimating viscosity influences the optimum operating wall temperature, thereby giving an insight into a selection of a proper viscosity model. The optimum helical number is not affected by fluid properties and wall temperature. The heat transfer to pumping ratio is evaluated and it is found that the optimal value is influenced by the change in viscosity.

A review of the usage of highly viscous fluids in industrial applications

Highly viscous fluids (HVF) are used in food sector as raw materials (melted vegetable, animal fats) or finished products (chocolate, sorbets), in construction sector as liquid state of Phase Change Materials (PCM) used to store thermal energy inside building structure or building materials such as liquid concrete, bitumen and tar, in automotive industry as PCMs used to passively cool batteries, and many others. Some applications are rather new and lot of research has been done, in the last decade, to find mathematical models for predicting HVF behaviour, in heat and mass transfer processes in scraped surface heat exchangers, in vegetable fat melters and in waxy crude oil transport pipelines. Better results could be obtained by enhancing HVF thermal properties such as increasing the thermal conductivity of PCMs by adding metallic powders, or by finding new natural materials (vegetable fats) which can replace more expensive and harmful ones (waxes) for PCMs. This study was performed to shortly present the main applications in which HFVs are being used, the main advances and findings made in the last years and the current challenges and research possibilities which are likely to be explored in the future.

On a Study of Flow Past Non-Newtonian Fluid Bubbles

In the current work, we aim at finding an analytical solution to the problem of fluid flow past a pair of separated non-Newtonian fluid bubbles. These bubbles are assumed to be spherical and non-permeable with the non-Newtonian fluid, viz. the couple stress fluid filling their interior. Further, the bubbles are presumed to be static in the flow domain, where a Newtonian fluid streams past these bubbles with a constant velocity (U) along the negative x-direction. We developed a mathematical model in the bipolar coordinate system for the fluid flow outside the bubbles and the spherical coordinate system inside the bubbles to derive a separable solution for their respective governing equations. Furthermore, to evaluate the model's applicabilities on the industrial front, the data on some widely used industrial fluids are given as inputs to the model, such as density, the viscosity of air or water for the fluid flow model developed for the region outside the fluid bubbles and the data on Cyclopentane or DIDP (non-Newtonian) for that within the bubbles. Some interesting findings are: the pressure in the outer region of the bubbles is higher when filled with low viscous industrial fluid, Cyclopentane, than a high viscous fluid, DIDP. Furthermore, an increase in the viscosity of Cyclopentane did not alter the pressure distribution in the region outside the bubbles. However, there is a considerable effect on this pressure in the case of DIDP bubbles.

Experimental investigations to evaluate surfactant role on absorption capacity of nanofluid for CO2 utilization in sustainable crude mobilization

Carbon dioxide (CO2) utilization for oilfield applications is affected by viscous fingering which leads to premature breakthrough without showing any appreciable impact on oil recovery and storage. Therefore, to control these issues, CO2 is often injected with high viscous fluid i.e. nanofluid. However, nanofluid efficacy can be further improved by inclusion of a surfactant that not only increases specific area of CO2 [via interfacial tension (IFT) reduction] but also increases CO2 absorption capacity of nanofluid through formation of foam. Thus, in this study, a new colloidal solution of anionic surfactant (i.e. sodium dodecyl sulfate, SDS, 0.16–0.24 wt%) and polymer based single-step silica nanofluid of varying concentration (0.1–1.0 wt%) was proposed for subsurface carbon utilization in CO2 absorption, IFT reduction, and fossil fuel displacement. CO2 absorption experiments showed that absorption was positively influenced by pressure and NP concentration, while increasing temperature showed reverse impact on CO2 absorption. In addition, SDS ensured formation of a Pickering foam which made CO2 to retain inside for over 10 days (an increase of 67%) in SDS treated nanofluid, higher than 6 days of simple nanofluid. Pickering CO2 foam of SDS treated nanofluids was also envisaged for IFT reduction of crude oil, to identify role of these nanofluids in crude mobilization from porous reservoir. CO2 absorption capacity of nanofluid exhibited inverse relationship with IFT value of crude oil. Finally, displacement experiments were conducted which also support inclusion of SDS in silica nanofluid for reduced water cut and higher fossil fuel recovery from porous media. Initially, the oil recovery was only 42% with water and 52% with 1 wt% NP concentration. However, the highest oil recovery was 61% when 1 wt% NP/0.16 wt% SDS combination was used.