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Hole cleaning is one of the most important aspects of extractive drilling operations. When drill cuttings combine with drilling fluids, cutting bed gel is created, which becomes extremely challenging to remove while drilling. One of the functions of drilling fluid when the flow is static is to maintain the drill bits' suspension. However, the settling of drill bits makes this nearly impossible. In this paper, the influence of fluid viscosity on hole cleaning performance was critically studied through a series of laboratory experiments. The effects of different viscosity levels on hole cleaning were investigated. This paper evaluated the use of lecithin and carboxymethyl hydroxyethyl cellulose (CMHEC) as a viscosifier and fluid loss agent in oil-based drilling fluid. The rheological properties of the formulated drilling fluids were determined at various temperatures according to the API 13B-2 specifications in order to identify the most suitable mud type for high-temperature drilling operations. From this study, it was discovered that Formulation B has the best rheology, with a plastic viscosity (PV) of 12, 7, and 7 cP at 30, 40, and 50 °C, respectively, while its yield point (YP) was found to be 30, 24, and 16, respectively. These values were compared with the generic oil-based formulation (A), which had a plastic viscosity (VP) of 43, 39, and 22 cP at 30, 40, and 50 °C, respectively, while its yield point (YP) was found to be 38, 20, and 26, respectively. The findings show that formulation B has a significant resistance to high temperatures, which means that it can be applied to drilling operations in reservoirs with high temperatures. It is more environmentally friendly. Furthermore, this paper explores the implications of the results in terms of the efficiency of hole cleaning and the drilling process relative to the viscosity of oil-based drilling fluid. This paper concludes by providing suggestions for improving drilling efficiency through the selection of an appropriate drilling fluid viscosity.

Hole cleaning is one of the most important aspects of extractive drilling operations. When drill cuttings combine with drilling fluids, a cutting bed gel is created, which becomes extremely challenging to remove while drilling. One of the functions of drilling fluid, when the flow is static, is to maintain the drill bits' suspension. However, the settling of drill bits makes this nearly impossible. In this paper, the influence of fluid viscosity on hole cleaning performance was critically studied through a series of laboratory experiments. The effects of different viscosity levels on hole cleaning were investigated. This paper evaluated the use of lecithin and carboxymethyl hydroxyethyl cellulose (CMHEC) as a viscosifier and fluid loss agent in oil-based drilling fluid. The rheological properties of the formulated drilling fluids were determined at various temperatures according to the API 13B-2 specifications in order to identify the most suitable mud type for high-temperature drilling operations. From this study, it was discovered that Formulation B has the best rheology, with a plastic viscosity (PV) of 12, 7, and 7 cP at 30, 40, and 50 °C, respectively, while its yield point (YP) was found to be 30, 24, and 16, respectively. These values were compared with the generic oil-based formulation (A), which had a plastic viscosity (VP) of 43, 39, and 22 cP at 30, 40, and 50 °C, respectively, while its yield point (YP) was found to be 38, 20, and 26, respectively. The findings show that formulation B has a significant resistance to high temperatures, which means that it can be applied to drilling operations in reservoirs with high temperatures. It is more environmentally friendly. Furthermore, this paper explores the implications of the results in terms of the efficiency of hole cleaning and the drilling process relative to the viscosity of oilbased drilling fluid. This paper concludes by providing suggestions for improving drilling efficiency through the selection of an appropriate drilling fluid viscosity. [ABSTRACT FROM AUTHOR]

A revisiting of the Lindemann criterion under the recently established minimal viscosity formulation is proposed which uncovers intriguing insights into the melting process. The approach suggests that melting involves competition between the electron rest energy and the thermal one caused by temperature increase when considering a defect-free crystal structure. However, when accounting for the role of vacancies in the melting process, the analysis suggests that the key competing factors are the thermal energy and the one needed for vacancy migration. The estimated value of the Lindemann constant, in this case, is close to the reported values and with recent simulations studying the correlation between Born and Lindemann melting criteria. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Droplet coalescence process is important in many applications and has been studied extensively when two droplets are surrounded by gas. However, the coalescence dynamics would be different when the two droplets are surrounded by an external viscous liquid. The coalescence of immiscible droplets in liquids has not been explored. In the present research, the coalescence of two immiscible droplets in low- and high-viscosity liquids is investigated and compared with their miscible counterparts experimentally. The coalescence dynamics is investigated via high-speed imaging, and theoretical models are proposed to analyze the growth of the liquid bridge. We find that, the liquid bridge r evolves differently due to the constraint from the triple line in the bridge region, which follows r ∝ t 2 / 3 for low-viscosity surroundings. While for high-viscosity surroundings, the liquid bridge grows at a constant velocity u r which varies with the surrounding viscosity μ s as u r ∝ μ s 1 / 2. In the later stage of the bridge growth, the bridge evolution again merges with the well-established power-law regime r ∝ t 1 / 2 , being either in low or high-viscosity liquids. Moreover, a new inertia-viscous-capillary timescale is proposed, which unifies the combined influence of inertia, viscous, and capillary forces on the evolution of the liquid bridge in liquid environments, highlighting the joint role of inertia and viscous resistance in the coalescence process. [ABSTRACT FROM AUTHOR]

Bedding planes are abundant in shale oil reservoirs, but the intrinsic mechanism of fracture-height containment by these weak interfaces remains unclear. To investigate the effects of interface properties, stress conditions, and fracturing fluid viscosity on the vertical propagation of fracture heights in laminated shale oil reservoirs, a three-dimensional hydro-mechanical coupling numerical model was developed. The model is based on the 3D discrete lattice algorithm (DLA), which replaces the balls and contacts in the conventional synthetic rock mass model (SRM) with a lattice consisting of spring-connected nodes, resulting in improved computational efficiency. Additionally, the interaction between hydraulic fractures and bedding planes is automatically computed using a smooth joint model (SJM), without making any assumptions about fracture trajectories or interaction conditions. The results indicate that a higher adhesive strength of the laminated surface promotes hydraulic fracture propagation across the interface. Increasing the friction coefficient of the laminated surface from 0.15 to 0.91 resulted in a twofold increase in the fracture height. Furthermore, as the difference between vertical and horizontal principal stresses increased, the longitudinal extension distance of the fracture height significantly increased, while the activated area of the laminar surface decreased dramatically. Moreover, increasing the viscosity of the fracturing fluid led to a decrease in filtration loss along the laminar surface of the fracture and a rapid increase in net pressure, making the hydraulic fracture more likely to cross the laminar surface directly. Therefore, for heterogeneous shale oil reservoirs, a reverse-sequence fracturing technique has been proposed to enhance the length and height of the fracture. This technique involves using a high-viscosity fracturing fluid to increase the fracture height before the main construction phase, followed by a low-viscosity slickwater fracturing fluid to activate the bedding planes and promote fracture complexity. To validate the numerical modeling results, five sets of laboratory hydraulic fracturing physical simulations were conducted in Jurassic terrestrial shale. The findings revealed that as the vertical stress difference ratio increased from 0.25 to 0.6, the vertical fracture area increased by 1.98 times. Additionally, increasing both the injection displacement and the viscosity of the fracturing fluid aided in fracture height crossing of the laminar facies. These results from numerical simulation and experimental studies offer valuable insights for hydraulic fracturing design in laminated shale oil reservoirs. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Bedding planes are abundant in shale oil reservoirs, but the intrinsic mechanism of fracture-height containment by these weak interfaces remains unclear. To investigate the effects of interface properties, stress conditions, and fracturing fluid viscosity on the vertical propagation of fracture heights in laminated shale oil reservoirs, a three-dimensional hydro-mechanical coupling numerical model was developed. The model is based on the 3D discrete lattice algorithm (DLA), which replaces the balls and contacts in the conventional synthetic rock mass model (SRM) with a lattice consisting of spring-connected nodes, resulting in improved computational efficiency. Additionally, the interaction between hydraulic fractures and bedding planes is automatically computed using a smooth joint model (SJM), without making any assumptions about fracture trajectories or interaction conditions. The results indicate that a higher adhesive strength of the laminated surface promotes hydraulic fracture propagation across the interface. Increasing the friction coefficient of the laminated surface from 0.15 to 0.91 resulted in a twofold increase in the fracture height. Furthermore, as the difference between vertical and horizontal principal stresses increased, the longitudinal extension distance of the fracture height significantly increased, while the activated area of the laminar surface decreased dramatically. Moreover, increasing the viscosity of the fracturing fluid led to a decrease in filtration loss along the laminar surface of the fracture and a rapid increase in net pressure, making the hydraulic fracture more likely to cross the laminar surface directly. Therefore, for heterogeneous shale oil reservoirs, a reverse-sequence fracturing technique has been proposed to enhance the length and height of the fracture. This technique involves using a high-viscosity fracturing fluid to increase the fracture height before the main construction phase, followed by a low-viscosity slickwater fracturing fluid to activate the bedding planes and promote fracture complexity. To validate the numerical modeling results, five sets of laboratory hydraulic fracturing physical simulations were conducted in Jurassic terrestrial shale. The findings revealed that as the vertical stress difference ratio increased from 0.25 to 0.6, the vertical fracture area increased by 1.98 times. Additionally, increasing both the injection displacement and the viscosity of the fracturing fluid aided in fracture height crossing of the laminar facies. These results from numerical simulation and experimental studies offer valuable insights for hydraulic fracturing design in laminated shale oil reservoirs.

ABSTRAK Viskositas merupakan sifat penting dalam banyak aplikasi industri seperti minyak, cat, adhesif, dan bahan kimia. Kualitas bahan material sebagai bahan baku industri memerlukan kualitas yang baik seperti sifat viskositas. Diperlukan sebuah alat pengukuran yang efektif dan presisi dalam mengetahui kualitas bahan berdasarkan sifat viskositasnya. Salah satunya pengukuran berbasis digital dan mikrokontroler. Penelitian ini bertujuan untuk merancang alat peraga viskositas yang dilengkapi dengan sensor mini reed switch magnetic berbasis Arduino. Alat peraga ini menggunakan sensor mini reed switch magnetic sebagai detektor pergerakan bola baja di dalam tabung. Sensor ini menghasilkan sinyal yang dikirim ke Arduino, kemudian mengolah data dan menampilkan nilai viskositas pada layar LCD. Metode penelitian ini menggunakan penelitian eksperimen berbasis laboratorium dengan melakukan karakterisasi viskositas skala laboratorium menggunakan lima larutan fluida yaitu air, minyak goreng bekas, minyak goreng baru, oli bekas dan oli baru. Sampel viskositas dimasukkan ke dalam tabung, dan bola baja ditempatkan di dalam larutan. Motor stepper kemudian menggerakkan bola baja dengan kecepatan yang ditentukan, dan sensor reed switch magnetic mendeteksi pergerakan bola tersebut. Data yang diperoleh dari sensor dikirim ke Arduino, diolah, dan hasil viskositas ditampilkan pada layar LCD. Hasil pengukuran besar nilai viskositas fluida air, minyak goreng bekas, minyak goreng baru, oli bekas, dan oli baru berturut-turut menghasilkan (satuan Pa.s) 2,12; 3,18; 2,84; 3,52; dan 7,71. Hasil pengujian menunjukkan bahwa alat peraga viskositas ini mampu memberikan hasil yang akurat dan konsisten dalam mengukur viskositas larutan fluida dengan rata-rata eror 7,425% dibandingkan dengan alat peraga viskositas konvensional. Alat peraga ini juga dapat digunakan untuk mengukur viskositas berbagai jenis cairan dengan penyesuaian parameter yang sesuai. Kata kunci: viskositas fluida; sensor mini reed switch magnetic. ABSTRACT Viscosity is an important property in many industrial applications such as oils, paints, adhesives, and chemicals. The quality of materials as industrial raw materials requires good quality such as viscosity properties. An effective and precise measurement tool is needed to determine the quality of materials based on their viscosity properties. One of them is digital and microcontroller based measurements. This research aims to design a viscosity demonstration tool equipped with an Arduino-based magnetic mini reed switch sensor. This teaching aid uses a mini reed switch magnetic sensor as a detector for the movement of steel balls in the tube. This sensor produces a signal which is sent to the Arduino, then processes the data and displays the viscosity value on the LCD screen. This research method uses laboratory-based experimental research by conducting laboratory-scale viscosity characterization using five fluid solutions, namely water, used cooking oil, new cooking oil, used oil and new oil. The viscosity sample is put into a tube, and a steel ball is placed in the solution. The stepper motor then moves the steel ball at a specified speed, and a magnetic reed switch sensor detects the movement of the ball. The data obtained from the sensor is sent to Arduino, processed, and the viscosity results are displayed on the LCD screen. The results of measuring the fluid viscosity values of water, used cooking oil, new cooking oil, used oil and new oil respectively produced (Pa.s units) 2.12; 3.18; 2.84; 3.52; and 7.71. The test results show that this viscosity probe is able to provide accurate and consistent results in measuring the viscosity of fluid solutions with an average error of 7.425% compared to conventional viscosity probes. This instrument can also be used to measure the viscosity of various types of liquids with appropriate parameter adjustments. Keywords: fluid viscosity; magnetic mini reed switch sensor.

Abstract The stress field is a critical factor for fracture propagation in hydraulic fracturing. Attention should be paid to fracture propagation with the nonuniform stress field. A stress field with gradient was established to investigate the influence of the nononuniform stress on fracture propagation. Based on the three‐dimensional block distinct element model the fracture propagation law with nononuniform stress was obtained. The mechanism of stress gradient and magnitude of uneven fracture propagation was revealed. Aiming at the uneven propagation, the influence of elastic modulus and construction parameters was analyzed. The results show that the influence of the elastic modulus follows the χ2 distribution equation and the influence of construction parameters can be expressed by the product of the injection rate and fluid viscosity. This conclusion is of theoretical significance for fracturing with nonuniform in situ stress.

The liver is a highly vascularized organ where fluid properties, including vascular pressure, vessel integrity and fluid viscosity, play a critical role in gross mechanical properties. To study the effects of portal pressure, liver confinement, fluid viscosity, and tissue crosslinking on liver stiffness, water diffusion, and vessel size, we applied multiparametric magnetic resonance imaging (mpMRI), including multifrequency magnetic resonance elastography (MRE) and apparent diffusion coefficient (ADC) measurements, to ex vivo livers from healthy male rats (13.6±1.6 weeks) at room temperature. Four scenarios including altered liver confinement, tissue crosslinking, and vascular fluid viscosity were investigated with mpMRI at different portal pressure levels (0-17.5 cmH 2 O). Our experiments demonstrated that, with increasing portal pressure, rat livers showed higher water content, water diffusivity, and increased vessel sizes quantified by the vessel tissue volume fraction (VTVF). These effects were most pronounced in native, unconfined livers (VTVF: 300±120%, p <0.05, ADC: 88±29%, p <0.01), while still significant under confinement (confined: VTVF: 53±32%, p <0.01, ADC: 28±19%, p <0.05; confined-fixed: VTVF: 52±20%, p<0.001, ADC: 11±2%, p <0.01; confined-viscous: VTVF: 210±110%, p <0.01, ADC: 26±9%, p <0.001). Softening with elevated portal pressure (-12±5, p <0.05) occurred regardless of confinement and fixation. However, the liver stiffened when exposed to a more viscous inflow fluid (11±4%, p <0.001). Taken together, our results elucidate the complex relationship between macroscopic-biophysical parameters of liver tissue measured by mpMRI and vascular-fluid properties. Influenced by portal pressure, vascular permeability, and matrix crosslinking, liver stiffness is sensitive to intrinsic poroelastic properties, which, alongside vascular architecture and water diffusivity, may aid in the differential diagnosis of liver disease. Using highly controllable ex vivo rat liver phantoms, hepatic biophysical properties such as tissue-vascular structure, stiffness, and water diffusivity were investigated using multiparametric MRI including multifrequency magnetic resonance elastography (MRE) and diffusion-weighted imaging (DWI). Through elaborate tuning of the experimental conditions such as the static portal pressure, flow viscosity, amount and distribution of fluid content in the liver, we identified the contributions of the fluid component to the overall imaging-based biophysical properties of the liver. Our finding demonstrated the sensitivity of liver stiffness to the hepatic poroelastic properties, which may aid in the differential diagnosis of liver diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, we propose a driving waveform with a complex ramp pulse for an electrowetting display system. The relationship between the contact angle and viscosity of inks was calculated based on the fluid-motion characteristics of different viscosities. We obtained the suitable range of viscosity and voltage in the liquid–oil–solid three-phase contact display system. We carried out model simulation and driving waveform design. The result shows that the driving waveform improves the response speed and aperture ratio of electrowetting. The aperture ratio of electrowetting pixels is increased to 68.69%. This research is of great significance to optimizing the structure of fluid material and the design of driving waveforms in electrowetting displays. [ABSTRACT FROM AUTHOR]

The stress field is a critical factor for fracture propagation in hydraulic fracturing. Attention should be paid to fracture propagation with the nonuniform stress field. A stress field with gradient was established to investigate the influence of the nononuniform stress on fracture propagation. Based on the three‐dimensional block distinct element model the fracture propagation law with nononuniform stress was obtained. The mechanism of stress gradient and magnitude of uneven fracture propagation was revealed. Aiming at the uneven propagation, the influence of elastic modulus and construction parameters was analyzed. The results show that the influence of the elastic modulus follows the χ2 distribution equation and the influence of construction parameters can be expressed by the product of the injection rate and fluid viscosity. This conclusion is of theoretical significance for fracturing with nonuniform in situ stress. [ABSTRACT FROM AUTHOR]

Wiped film molecular distillation is a kind of evaporation device with rotating scraping film structure, which is used to separate and purify viscous materials at molecular level. The feed pump of a wiped film molecular distillation is a centrifugal pump driven by a brushless DC motor. The fluid flow at the outlet has an important effect on the evaporation process. Based on the geometric model of the test pump generated by Gambit, the unsteady flow and head in the pump under optimal, low flow and shut off conditions were calculated, and the influence of liquid viscosity on the flow parameter pulsation behind the impeller, that is, inside the volute was investigated. The head calculated by unsteady flow model and steady flow model is compared with the experimental values. In addition, the calculated liquid velocity distribution during water transport is compared with the measured results of LDV in detail. The results show that the increase of fluid viscosity weakens the flow parameter pulsation behind the impeller of the feed pump and the flow separation tendency near the blade face.

This study presents the structural optimization for the sensitivity improvement of an innovative viscosity and density sensor for viscous fluid characterization. Cantilever beams with varying steps are prototyped and fabricated by additive manufacturing (AM) techniques for experimental validation with laser Doppler vibrometer (LDV). Experiment results agree with that of numerical simulation. Moreover, the creation of steps in thickness significantly improves the sensor's performance and sensitivities. Step-in-thickness cantilever beam is more efficient in optimizing the relative sensitivity for viscosity sensing. The proposed structure associated with the theory provide a foundation for further design of resonant beam viscosity and density sensors. [ABSTRACT FROM AUTHOR]

For low viscous fluids, the D 32 tends to increase almost linearly with the increase in Q v , regardless of whether or not the LF-FF transition occurs during this process. For highly viscous fluids, there will be a steep increase in D 32 during the LF-FF transition, but D 32 can remain stable over a wide range by continuing to increase the Q v. [Display omitted] • Viscosity's role in FF mode clarified using glycerol-water. • Transition to FF mode revisited, metrics analyzed comprehensively. • High viscosity fosters smoother films, smaller droplets, stable D 32. • Empirical FF characteristics relationships proposed. Film fragmentation (FF) stands as a well-recognized disintegration mode renowned for its substantial throughput in droplet or particle production facilitated by rotary disk atomizers. Despite its prominence, a dearth of comprehensive information persists regarding the FF mode, particularly regarding the potential influence of viscosity on FF characteristics. Our study undertakes experimental investigations utilizing glycerol/water as the working fluids to elucidate FF characteristics across a spectrum of viscosities. The film and droplet metrics were systematically evaluated at various viscosities. Empirical relationships were established to estimate the FF characteristics with cross-validation against other works. Our findings underscore the stabilizing influence of high fluid viscosity on the liquid film, facilitating its complete development and contributing to the maintenance of a diminutive D 32 across a broad flow spectrum. This research yields pivotal theoretical insights pertinent to the centrifugal atomization of relatively high viscosity fluids, offering pathways for achieving substantial throughput in atomization processes. [ABSTRACT FROM AUTHOR]

In this paper, we propose a driving waveform with a complex ramp pulse for an electrowetting display system. The relationship between the contact angle and viscosity of inks was calculated based on the fluid-motion characteristics of different viscosities. We obtained the suitable range of viscosity and voltage in the liquid–oil–solid three-phase contact display system. We carried out model simulation and driving waveform design. The result shows that the driving waveform improves the response speed and aperture ratio of electrowetting. The aperture ratio of electrowetting pixels is increased to 68.69%. This research is of great significance to optimizing the structure of fluid material and the design of driving waveforms in electrowetting displays.

Globally, fuel energy has become a crucial issue in fulfilling energy demand; new oil/gas wells should be drilled safely and efficiently to achieve the well target. Cutting transport in deviated wells is directly affected by influencing parameters such as viscosity, annulus velocity of drilling mud, and hole inclination. As cuttings transport significantly affects drilling costs, time, and oil/gas well integrity. Poor hole cleaning efficiency could cause many drilling issues, including excessive torque and drag, Pipe washout and jamming, bit balling and washout, etc. Therefore, hole cleaning investigation requires a deep understanding of all influential parameters.The results of this study were utilized to investigate cutting transport performance, employing three different kinds of drilling mud. The investigational work was performed by a 10-feet elongated invisible pipe of 5-inch diameter and a steel pipe of 2-inch diameter as the test section. The cutting transport performance (CTP) was computed based on weight data for every single test. At different flow regimes, viscosity was examined in addition to two other influential parameters, namely fluid velocity and hole inclination. At all angles, during turbulent flow, Cutting Transport performance has enhanced up to 10% by increasing viscosity while keeping velocity constant.Nevertheless, an increasing additional amount of viscosity will turn the flow condition from turbulent to transient or laminar flow, resulting in a 14% reduction in CTP. It also shows that increasing hole angle above 60 degrees with mud-2 positively affects cuttings transport performance. It will be improved up to 45%. Moreover, a maximum of 96 percent CTP can be attained by drilling fluid velocity. Therefore, this study properly investigates the influence of viscosity, velocity, and hole inclination on cutting transporter performance, as a result saving drilling time and reducing hidden costs, as well as lead to a prediction of the carrying capacity of fluids and facilitating the optimum design of vertical and directional wells. Moreover, this study provides a guideline to analyze and enable the adjustment of drilling parameters to optimize the overall drilling process.

We developed a 3D rotational viscometer model based on the finite volume method and analyzed the effects of the shear rate, glass bead solid fraction, and particle size on the viscosity of water and maltose syrup. We developed a novel Gidaspow model and introduced particle sphericity as a parameter. The effects of sphericity, solid fraction, and particle size on the viscosity of different fluids were simulated and calculated. Compared with the experimental findings, the maximum relative error was 10.7% before the solid fraction was 30%, and the calculated data suitably agree with the experimental results. The results also show that when the solid fraction is above 10%, the particle fluid viscosity increases with increasing shear rate and solid fraction and decreases with increasing sphericity and particle size. The novel Gidaspow equation can suitably predict the initial apparent viscosity of different solid–liquid mixtures before reaching a solid fraction of 50%. The new model has a wide range of applications and can be applied to arbitrary particle shapes (spherical range of 0–1) in various materials and fields. The proposed model can provide a reference for further theoretical and experimental studies on solid–liquid two-phase flow. [ABSTRACT FROM AUTHOR]

Fluid viscosity is one of the key factors affecting the cavitation characteristics of the Helico-axial Multiphase Pump (HAMP). In this paper, fluids with viscosities of 24.46 mm2/s, 48.48 mm2/s, 60.70 mm2/s, and 120.0 mm2/s were investigated by numerical simulation. The Ansys Fluent software was employed to conduct the simulation. The mixture multiphase flow model and the RNG k-ε turbulence model were adopted. The Singhal cavitation model was employed to consider the effects of the non-condensable gas on cavitation. An experiment was carried out to validate the numerical method. The results showed that the Net Positive Suction Head-available (NPSHA) of the pump decreased as the fluid viscosity increased. Under the critical NPSHA condition, the NPSHA decreased from 5.11 m to 3.68 m as the fluid viscosity increased from 24.46 mm2/s to 120.0 mm2/s. This suggested that the cavitation performance of the pump was deteriorated under high fluid viscosity. The impeller passage area occupied by the vapor increased when the fluid viscosity increased. Nearly half of the flow passages were occupied by cavitation bubbles when the fluid viscosity increased to 120.0 mm2/s. The vapor volume fraction, both on the suction surface and pressure surface of the blade, increased with the fluid viscosity. The vapor on the suction surface was mainly distributed in the region with the streamwise between 0 and 0.36 when the fluid viscosity was 24.46 mm2/s; while the high vapor volume fraction range increased to the streamwise of 0.42 when the fluid viscosity increased to 120.0 mm2/s. The higher vapor volume fraction corresponded with the lower pressure. It was also found that the turbulent kinetic energy, both on the suction surface and pressure surface, increased with the fluid viscosity, which was the favorite for producing more cavitation bubbles. Furthermore, the maximum velocity area was mainly concentrated in the inlet area of the impeller. The velocity distribution in the impeller was basically the same with the viscosity of 24.46 mm2/s and 48.48 mm2/s. When the viscosity further increased to 60.70 mm2/s, the maximum velocity area in the impeller was relatively large. This study provides a reference for designing the HAMP. [ABSTRACT FROM AUTHOR]

In this paper, the erosion performance of a new normally open arrow-type check valve spool was studied by the CFD method. The liquid phase is regarded as a continuous phase, and the particles are solved by a discrete phase model. Based on the verified numerical model, the effect law of five key factors, such as sealing surface Angle α/2, β/2, and particle mass flow rate, on the erosion of the valve spool sealing surface (VSSS) was studied. The maximum erosion rate of the VSSS is used as the evaluation index. The results show that the lower end of the sealing surface is the area with the most serious erosion damage to the VSSS, and the damage degree increases with the increase of α/2. In addition, the maximum erosion rate of the VSSS increases with the increase in particle mass flow and particle diameter and decreases with the increase in fluid viscosity. In terms of structure, reducing the sealing surface angle α/2 can reduce the erosion damage to the VSSS. [ABSTRACT FROM AUTHOR]

Many hydraulic fracturing experiments suggest that low-viscosity fluid tends to generate a complex fracture network, which may be beneficial for geo-energy production. However, the precise impacts of low-viscosity fluid on the fracture nucleation and propagation are unknown. This study focuses on the stress jump at weak interfaces (e.g., grain boundaries or natural fractures) caused by the contrast in Biot's coefficient, which is prevalent in hard rocks, and how failure may develop. We found that fracture nucleation at weak interfaces becomes favorable under certain Biot's coefficient contrast and fluid viscosity. Our numerical simulations of fluid injection through a borehole demonstrate that low-viscosity fluid injection can nucleate isolated fractures at remote interfaces without connecting to the main propagating fracture. These findings imply the necessity to consider Biot's coefficient variations within a rock mass in applications such as hydraulic fracturing or induced seismicity, especially when a diffused pressure gradient persists due to the low-viscosity fluid. • Tensile stress can develop at an interface whose Biot coefficient is lower. • A contrast in Biot coefficient and low fluid viscosity can promote remote fracturing. • Remote fracturing may be engineered to stimulate stiff and tight rock formations. [ABSTRACT FROM AUTHOR]

Aiming at the problem that the relationship between material properties and mixing performance was difficult to determine in the use of planetary centrifugal mixer（PCM）, the effects of fluid viscosity and density on the mixing performance of PCM were studied by computational fluid dynamics（CFD） simulation. Firstly, the computational domain was modeled and meshed by ICEM CFD, and the independence of the grid was analyzed. Then, the second order finite volume method and discrete phase model were used to solve the particle trajectories, low velocity regions and discrete particle distribution of PCM mixing fluids with different viscosity and density, and the mixing effect was quantitatively characterized by the mixing index defined. Finally, the influence mechanism of fluid viscosity and density on the mixing performance of PCM was analyzed. The results show that fluid viscosity and density change the mixing effect of PCM mainly by affecting the flow field structure. The growth of fluid viscosity contributes the increase of optical speed ratio and the smaller value of mixing index that can be achieved; the growth of fluid density contributes the decrease of optical speed ratio and the greater values of mixing index that can be achieved. The research provides references for the use and optimization of PCM. [ABSTRACT FROM AUTHOR]

In this paper, we present a numerical study of hydraulic fracturing in brittle rock by using particle flow simulation. The emphasis is put on the influence of in situ stress, differential stress, fluid injection rate, fluid viscosity and borehole size on hydraulic fracturing behavior. To this end, an improved hydromechanical coupling model is first introduced to better describe fluid flow and local deformation of particle-based rocks. A series of parameter sensitivity studies are then conducted under the framework of particle flow simulation. Modelling results suggest that the breakdown pressure and time to fracture both linearly increase with confining stress, and hydraulic fracturing patterns present a distinct transition from brittle to ductile. Fluid injection rate and fluid viscosity have similar influences on hydraulic fracturing propagation, their value decrease leads to borehole pressure decrement and time to fracture prolongation. However, the former mainly controls the time to initial cracking, while the latter largely decides the duration of fracturing propagation. As for borehole radius, its increases can directly enhance the fluid diffusion zone, which further intensifies the nonlinear property of borehole pressure, leads to breakdown pressure decrease, prolongs time to fracture and forms more complex hydraulic fractures. [ABSTRACT FROM AUTHOR]

The tight heterogeneous glutenites are typically characterized by highly variable lithology, low/ultra-low permeability, significant heterogeneity, and a less-developed natural fracture system. It is of great significance for economic development to improve hydraulic fracture complexity and stimulated reservoir volume. To better understand the hydraulic fracturing mechanism, a large-scale experimental test on glutenite specimens was conducted and the hydraulic fracture propagation behaviors and focal mechanism were analyzed. A three-dimensional numerical model was developed to reproduce the hydraulic fracture evolution process and investigate the effects of operating procedures on hydraulic fracture geometry and stimulated reservoir volume. A simultaneous variable injection rate and fluid viscosity technology was proposed to increase the hydraulic fracture complexity and stimulated reservoir volume. The results indicate that four fracturing behaviors can be observed, namely, penetration, deflection, termination, and bifurcating, in the laboratory experiment. Tensile events tend to appear during the initiation stage of hydraulic fracture growth, while shear events and compressive events tend to appear during the non-planar propagation stage. The shear and compressive mechanisms dominate with an increase in the hydraulic fracture complexity. The variable injection rate technology and simultaneous variable injection rate and fluid viscosity technology are effective techniques for fracture geometry control and stimulated reservoir volume enhancement. The key to improve hydraulic fracture complexity is to increase the net pressure in hydraulic fractures, cause evident pressure fluctuations, and activate or communicate a wide range of natural discontinuities. The results can provide a better understanding of the fracture geometry control mechanism in tight heterogeneous glutenites, and offer a guideline for treatment design and optimization of well performance. [ABSTRACT FROM AUTHOR]

Based on Reynolds equation and finite element method,the pressure distribution of fluid penetrating into the rail surface crack was calculated by the two-dimensional wheel/rail rolling contact model. Then the stress intensity factor of the crack tip was analyzed,and the effect of fluid viscosity on the rolling contact fatigue crack growth was studied. The results show that the crack propagation mode transforms from type Ⅱ to typeⅠ in the presence of liquid on the surface of the rail,and the liquid that penetrates into the crack is more likely to cause material peeling. The greater the viscosity,the larger the average crack propagation angle,and the propagation path changes from smooth to tortuousthe. When the viscosity is constant,the larger the initial angle of crack,the lower the crack growth rate. And with the increase of viscosity,the crack growth rate decreases.

Fluid viscosity is one of the key factors affecting the cavitation characteristics of the Helico-axial Multiphase Pump (HAMP). In this paper, fluids with viscosities of 24.46 mm2/s, 48.48 mm2/s, 60.70 mm2/s, and 120.0 mm2/s were investigated by numerical simulation. The Ansys Fluent software was employed to conduct the simulation. The mixture multiphase flow model and the RNG k-ε turbulence model were adopted. The Singhal cavitation model was employed to consider the effects of the non-condensable gas on cavitation. An experiment was carried out to validate the numerical method. The results showed that the Net Positive Suction Head-available (NPSHA) of the pump decreased as the fluid viscosity increased. Under the critical NPSHA condition, the NPSHA decreased from 5.11 m to 3.68 m as the fluid viscosity increased from 24.46 mm2/s to 120.0 mm2/s. This suggested that the cavitation performance of the pump was deteriorated under high fluid viscosity. The impeller passage area occupied by the vapor increased when the fluid viscosity increased. Nearly half of the flow passages were occupied by cavitation bubbles when the fluid viscosity increased to 120.0 mm2/s. The vapor volume fraction, both on the suction surface and pressure surface of the blade, increased with the fluid viscosity. The vapor on the suction surface was mainly distributed in the region with the streamwise between 0 and 0.36 when the fluid viscosity was 24.46 mm2/s; while the high vapor volume fraction range increased to the streamwise of 0.42 when the fluid viscosity increased to 120.0 mm2/s. The higher vapor volume fraction corresponded with the lower pressure. It was also found that the turbulent kinetic energy, both on the suction surface and pressure surface, increased with the fluid viscosity, which was the favorite for producing more cavitation bubbles. Furthermore, the maximum velocity area was mainly concentrated in the inlet area of the impeller. The velocity distribution in the impeller was basically the same with the viscosity of 24.46 mm2/s and 48.48 mm2/s. When the viscosity further increased to 60.70 mm2/s, the maximum velocity area in the impeller was relatively large. This study provides a reference for designing the HAMP.

• Magnetic control on the generation of ferrofluid droplets from capillaries is realized. • A proposed correlation predicts the final volume of ferrofluid droplets grows in viscous fluids. • The impacts of magnetic force, viscous drag, and inertial forces on droplets' volume, deformation ratio, limit major axis, and neck breakup behavior are studied. • The rate of neck breakup of ferrofluid droplets is decelerated by viscous drag force. • Ferrofluid droplet necks exhibit self-similar breakup behavior at different magnetic Bond and Weber numbers. The controlled generation of droplets is crucial in bioassays, chemical analysis, and inkjet printing. Despite progress in droplet formation dynamics within liquid–liquid systems, improving the controllability and flexibility of manipulating droplets is still necessary. Here, we employ a non-uniform magnetic field for non-contact control of ferrofluid droplet generation in a vertical capillary. A correlation function predicts final ferrofluid droplet volumes with an average relative error of only 6.33%. Our study demonstrates that the magnetic field actively regulates droplets' volume, deformation, and generation period. In the final stages of droplet formation, we observe a unique neck rupture mechanism influenced by the viscosity of the continuous-phase fluid, distinct from observations in air. Scaling laws fit the minimum neck and position variations, revealing self-similar neck rupture behavior for droplets at different Bond and Weber numbers. These insights into droplet dynamics have potential applications across various technological domains. [ABSTRACT FROM AUTHOR]

Abstract Compound nanoparticle drug delivery system plays an important role in the interaction with lymph nodes. There are three primary types of lymphocytes: B cells, T cells, and natural killer cells. When the cells of the immune system turn carcinogenic, they assault body cells. The lymph fluid plays an important role in attacking healthy cells of the body; hence, this paper aimed to design a drug delivery system, which can efficiently direct nanoparticles to target the infected cells, helping in high-speed elimination of such cells. The proposed design depends on the interaction between these molecules, and the intelligent nano-controller has the ability to guide the nanoparticles by anaerobic contact. The proposed design proved that the smaller the nanoparticle size and density, the less dynamic viscosity of the liquid would be, which would reflect its resistance to flow. In addition, it was concluded that hydrogen molecules play a significant role in reducing lymphatic fluid resistance due to their low density.

In this paper, we present a numerical study of hydraulic fracturing in brittle rock by using particle flow simulation. The emphasis is put on the influence of in situ stress, differential stress, fluid injection rate, fluid viscosity and borehole size on hydraulic fracturing behavior. To this end, an improved hydromechanical coupling model is first introduced to better describe fluid flow and local deformation of particle-based rocks. A series of parameter sensitivity studies are then conducted under the framework of particle flow simulation. Modelling results suggest that the breakdown pressure and time to fracture both linearly increase with confining stress, and hydraulic fracturing patterns present a distinct transition from brittle to ductile. Fluid injection rate and fluid viscosity have similar influences on hydraulic fracturing propagation, their value decrease leads to borehole pressure decrement and time to fracture prolongation. However, the former mainly controls the time to initial cracking, while the latter largely decides the duration of fracturing propagation. As for borehole radius, its increases can directly enhance the fluid diffusion zone, which further intensifies the nonlinear property of borehole pressure, leads to breakdown pressure decrease, prolongs time to fracture and forms more complex hydraulic fractures.

The erosion failure of oil transmission lines is mainly caused by the migration of quartz, sand, silt and clay into the processing units. Apart from the solid particles, the fluid viscosity also impacts the erosion-related failure of the processing units. The role of sand carrier viscosity in wear damage to pipelines, however, is not well understood. In this study, the wear performance of carbon steel coupons in polymer-sand-water slurry was investigated by varying the slurry viscosity from 1 to 19 cP. The water-soluble polyvinyl alcohol was used to modify the viscosity of the carrier fluid. At a fluid velocity of 6 m/s, the Reynolds number decreased from 165,000 to 8684 with a rise in viscosity from 1 to 19 cP. Similarly, at 10 m/s, the Reynolds number decreased from 330,000 to 17,368 for a similar change in the fluid viscosity. Each coupon was exposed to the fluid stream for 10 hours. Universal scanning probe microscopy (USPM) revealed more rough topology at lower viscosities and relatively smoother topology at higher viscosities. The erosion rate decreased from 6.31 ± 0.41 to 1.27 ± 0.16 mm/year and microhardness from 102 VHN to 98.2 VHN with a rise in viscosity from 1 to 19 cP. The USPM method revealed slightly higher erosion rates as compared to the weight loss method. [ABSTRACT FROM AUTHOR]

Debris flows are typical two-phase flows that commonly occur with entrainment. By involving sediment materials, the fluid viscosity of debris flow may change significantly along with the variety of solid volume fraction, which further influences debris flow routing. To address this issue, a two-phase model is incorporated with a correlation for the apparent viscosity of the mixture and an entrainment formula, which is applied for studying how the changing fluid viscosity affects the interaction force between the solid and fluid phases during flow propagation. A second-order accuracy numerical scheme based on the finite volume method is applied to solve model equations. The numerical results correlate well with the available experimental data, and indicate the importance of viscosity changes in debris flow routing. [ABSTRACT FROM AUTHOR]

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Numerical simulation is very useful for understanding the hydraulic fracture (HF) re-orientation mechanism from artificial weaknesses. In this paper, the UDEC T-W (Trigon–Weibull distribution) modeling method is adopted to simulate the hydraulic fracturing process in heterogeneous rocks. First, the reliability of this method is validated against previous laboratory experiments and numerical simulations. Then the effects of fluid rate, fluid viscosity, perforation angle and natural fracture (NF) on the HF re-orientation process in heterogeneous rocks are studied independently. The results show that the HF re-orientation process depends on the combined effect of these factors. The HF re-orientation distance increases significantly, the final HF re-orientation trajectory becomes more complex and the guiding effect of perforation on the HF propagation path is more evident with the increase of fluid rate, fluid viscosity, and perforation angle if the hydraulic fracturing is performed in relatively heterogeneous rocks, while the differential stress is the main influencing factor and is more likely to dictate the HF propagation path if the rocks become relatively homogeneous. However, increasing the fluid viscosity and fluid rate can attenuate the impact of differential stress and can promote HF propagation along the perforation direction. Besides, NFs are also the important factor affecting HF re-orientation and induce secondary HF re-orientation in some cases in heterogeneous rocks.

For many decades transformer oil has served as a well-known insulating medium. Its electrical properties, among others, have been studied in length. In recent years, with the increasing concern for the environment, alternative insulating liquids have been proposed. In the context of this concise review, such alternative fluids are investigated. Some conflicting evidence regarding experimental results that still persist are discussed and aspects of vegetable oils in need of further work are pointed out. [ABSTRACT FROM AUTHOR]

The results of the experiments on the influence of a positive-buoyancy-particle layer on the process of breaking and regularization of the standing gravity Faraday wave on free water surface in a rectangular vessel are discussed. The effect of increase in the particle layer thickness on the limit steepness of the regular wave and its dissipative properties is considered. It is shown that the use of highly concentrated polystyrene particle suspension as the upper layer modifies significantly the barotropic wave mode dynamics and ensures regularization of the waves with total suppression of their breaking mechanisms. [ABSTRACT FROM AUTHOR]

A novel method called tip-viscid electrohydrodynamic jet printing (TVEJ), which produces a viscous needle tip jet, was presented to fabricate a 3D composite osteochondral scaffold with controllability of fiber size and space to promote cartilage regeneration. The tip-viscid process, by harnessing the combined effects of thermal, flow, and electric fields, was first systematically investigated by simulation analysis. The influences of process parameters on printing modes and resolutions were investigated to quantitatively guide the fabrication of various structures. 3D architectures with high aspect ratio and good interlaminar bonding were printed, thanks to the stable fine jet and its predictable viscosity. 3D composite osteochondral scaffolds with controllability of architectural features were fabricated, facilitating ingrowth of cells, and eventually inducing homogeneous cell proliferation. The scaffold’s properties, which included chemical composition, wettability, and durability, were also investigated. Feasibility of the 3D scaffold for cartilage tissue regeneration was also proven by in vitro cellular activities.

Numerical investigations of the propagation of rolling contact fatigue crack filled by the liquid have been conducted. Two models of fluid crack interaction have been considered. In the first model called 䖓hydrostatic� the assumption of incompressible, inviscid and weightless liquid was accepted. It was also assumed that due to the wheel load the trapped liquid could not get outside the crack and its volume remained constant until the rising pressure would open up the crack mouth again. On this assumption the analysis has a steady-state character. In the second model it has been assumed that the crack is filled by the viscous, incompressible fluid and the fluid motion as well as the resulting pressure distribution can be represented by one-dimensional form of the Reynolds equation. The method for solving the problem of the coupled motion of liquid and crack faces has been developed and series of calculation were made. The method has been employed for the predicting of crack deformation in the course of wheel rolling

We are working on the development of a sensor that can calculate various vital signs from the signals measured by installing a Fiber Bragg Grating (FBG) sensor at the pulsation point of a living body. In this paper, the influence of blood flow parameters and sensor installation conditions on the FBG sensor signal was verified using two blood flow simulation models. From the results of our study, the following observations were made. The fluid pressure increases, the wavelength shift of the FBG sensor beca me larger. By contrast, an increase in the viscosity of the fluid was seen to cause a decrease in the displacement length of the Bragg wavelength. Fluid pressure and viscosity were observed to opposite effects on the FBG sensor signal. The Bragg wavelength shift of the FBG sensor was observed to be larger when the installation direction of the FBG sensor was perpendicular to the blood flow direction than in the parallel direction. However, FBG sensor signals with higher signal-to-noise (S/N) ratio were measured at an angle of 75 degrees than at an angle of 90 degrees, which is perpendicular to the blood flow direction. From the above results, the installation condition of the FBG sensor on the measurement signal and the influence of each parameter of blood flow were established. [ABSTRACT FROM AUTHOR]

The low power consumption and operability of magnetic controlled spiral capsule robots (MCSCRs) are important indexes that influence the interventional diagnosis and treatment of digestive tract. However, existing studies lack of analysis on the self-starting characteristics of MCSCRs. For simple and effective swimming of a MCSCR in a liquid environment, a self-starting characteristic model of MCSCR was proposed. A new portable electromagnetic propulsion device with dynamic rotating magnetic field and a MCSCR were also developed. A spatial magnetic field distribution model of a permanent magnet was constructed in accordance with the Biot-Savart law. This model was employed to determine the coupling characteristic relation between master and slave permanent magnets. A self-starting model of robots in a pipe filled with liquid was deduced, and the interaction laws of self-starting rotating speed, fluid viscosity, and axial thrust were determined. Results demonstrate that the self-starting rotating speed of robots increases with the increase in fluid viscosity, and the axial thrust is enhanced gradually as rotating speed increases. When the fluid viscosity is 0.1 Pa·s, the self-starting rotating speed reaches the minimum value (85 r/min). Self-starting control of robots with a low torque and a strong axial thrust can be realized by adjusting the self-starting distance and rotating speed between the master permanent magnet and robot. When the master permanent magnet is 29 mm away from the robot, the maximum coupling magnetic moment is the lowest (0.1 Pa·s). This study can provide theoretical supports to low-power rapid medical examination based on in vivo capsule robot. [ABSTRACT FROM AUTHOR]

This paper conducts a dynamical analysis of drill-string-like pipes based on the ground-breaking contribution of Païdoussis et al. (2008), in which the stability of a tubular cantilever conveying internal and external annular flows without spin is investigated. The innovations of this paper are generalized as follows: i) A spinning three-dimensional (3D) model is developed to simulate working drill strings; ii) Supported pipes instead of cantilevers are considered due to the stabilizers and heavy loads encountered at the free end (the drill bit); iii) Hamiltonian, instead of Newtonian, derivation is performed to achieve the governing equations of such system with gyroscopic effects induced by spinning motion and fluid–structure interaction (FSI), namely a doubly gyroscopic system; iv) 3D motions, involving in-plane and out-of-plane transverse motions, are studied; v) The frequencies, energy, mode shapes and time-domain responses to the initial conditions are comprehensively investigated to display the dynamical characteristics of the system. The results obtained reveal that the viscous external fluid, flow velocity, spinning speed as well as the gravity and axial pretension all have significant effects on the dynamical behaviors of the pipe. The dynamics of the present system has been demonstrated rather different from that of cantilevered structures without spin. • A spinning 3D model is developed to simulate working drill strings. • The stability evolutions and 3D motions of such a doubly gyroscopic structure are analyzed towards various parameters. • The dynamics of the present system is found rather different from that of cantilevered structures without spin. [ABSTRACT FROM AUTHOR]

• Fluid viscosity significantly influences dynamic behaviors of creeping granular flow. • The effect of particle size on core dynamics is more complicated. • Fitting formulas allow users to predict core erosion and precession. We report on experiments we have performed using a rotating drum to investigate the core dynamics and transport properties of granular mixtures with different particle sizes and different fluid viscosities. We used six different fluid viscosities in the experiments, obtained using air and five different fluid mixtures of water and glycerin, and we used particles of three different sizes. Image processing technology was employed to analyze the core dynamics and particle tracking velocimetry was used to measure the dynamic properties. The experimental results indicate that both the fluid viscosity and the particle size significantly affect the creeping flow of slurry granular flows. For a given particle size, an increase in the fluid viscosity causes the erosion and precession of the core to increase, while all the transport properties appear to decrease. However, the effects of variations in the particle size on the core dynamics and the transport properties are more complicated. It was found that the erosion rate can be expressed as an exponential function of the Stokes number, while the precession rate is a linear function of this parameter. Image, graphical abstract [ABSTRACT FROM AUTHOR]