Increase In Fluid Viscosity Research Articles

Numerical Simulation of Hydraulic Fracture Propagation in Unconsolidated Sandstone Reservoirs

In order to comprehensively understand the complex fracture mechanisms in thick and loose sandstone formations, we have carefully developed a coupled finite element numerical model that captures the complex interactions between fluid flow and solid deformation. This model is the cornerstone of our future exploration. Based on this model, the crack propagation problem of hydraulic fracturing under different engineering and geological conditions was studied. In addition, we conducted in-depth research on the key factors that shape the geometry of hydraulic fractures, revealing their subtle differences and complexities. It is worth noting that the sharp contrast between the stress profile and mechanical properties between the production layer and the boundary layer often leads to fascinating phenomena, such as the vertical merging of hydraulic fracture propagation. The convergence of cracks originating from adjacent layers is a recurring theme in these strata. Sensitivity analysis clarified our understanding, revealing that increased elastic modulus promotes longer crack propagation paths. As the elastic modulus increases from 12 GPa to 18 GPa, overall, the maximum crack width slightly decreases, with a less than 10% reduction rate. The increased fluid leakage rate will significantly shorten the length and width of hydraulic fractures (with a maximum decrease of over 70% in fracture width). The increase in viscosity of fracturing fluid causes a change in fracture morphology, with a reduction in length of about 32% and an increase in fracture width of about 25%. It is worth noting that as the leakage rate of fracturing fluid increases, the importance of the viscosity of fracturing fluid decreases relatively. Strategies such as increasing fluid viscosity or adding anti-filtration agents can alleviate these challenges and improve the efficiency of fracturing fluids. In summary, our research findings provide valuable insights that can provide information and optimization for hydraulic fracturing filling and fracturing strategies in loose sandstone formations, promoting more efficient and influential oil and gas extraction work.

Sour taste perception in fluids: The impact of sweet tastant, fluid viscosity, and individual salivary properties

Binary taste perception is widely studied in aqueous solutions but less investigated in non-Newtonian fluid systems. In this study, the effect of sweet tastants on the dynamic sour taste perception in thickened fluids and its underpinning oral processing factors were investigated. Subjects were tested for taste thresholds and salivary biochemical properties. By using hydroxypropyl methylcellulose (HPMC) as a thickening agent, subjects conducted sour taste evaluation, with and without maltose and/or HPMC, using descriptive sensory analyses. A simulated fluid shear elicited by fixed-frequency mastication was applied on thickened fluid sample oral processing during time-intensity sour taste evaluation. Results showed that adding maltose to fluid samples enhanced sour taste perception, and increasing fluid viscosity generally suppressed perceived maximum sour taste. Moreover, subjects with lower sour taste sensitivity and higher salivary buffering capacity reported overall lower sour taste intensity in most samples, validating the hypothesis that salivary properties importantly affect sour taste perception.

Experimental and Simulation Investigations of Proppant Transport and Distribution Between Perforation Clusters in a Horizontal Well

Summary Multistage hydraulic fracturing is widely used to stimulate tight reservoirs by means of plug and perforation technology. The proppant distribution between perforation clusters significantly impacts fracture conductivity and well productivity. Uneven slurry distribution is often the norm rather than the exception. Proppant transport behaviors and distribution characteristics are still poorly understood in a horizontal wellbore with clusters, especially at field scales. The objective is to propose an innovative and feasible method to quantitatively evaluate the distribution uniformity of proppant between clusters. In this work, we systematically investigate proppant migration and placement by means of laboratory tests and numerical simulation. Computational fluid dynamics (CFD) and the discrete element method (DEM) are coupled to analyze proppant-fluid flow. The experimental observation and results validate the numerical model and calibrate critical parameters. The transport efficiency (E) and normalized standard deviation (NSD) are used to evaluate proppant distribution. The effects of nine parameters on the E and NSD are investigated at field ranges. The calibrated CFD-DEM model is accurate in studying proppant distribution between multiple clusters. The toe bias is the primary distribution between clusters because of the large inertia originating from high injection rates. Fluid distribution and perforation configuration are critical factors that significantly change the toe bias at the cluster level. Fluid redistribution changes proppant distribution toward the heel. The inline up pattern has the best uniformity, followed by the 180° up-down pattern. The secondary characteristic is bottom-biased within a cluster. Increasing fluid viscosity, using small and light proppants, and pumping high-concentration slurry can improve proppant distribution. The slurry diversion into perforations is hardly changed unless external conditions change. The combination of high-concentration slurry and a large bed quickly induces premature screenout at the toe-side cluster, especially when injecting large and high-density particles. Slurry redistributes toward the heel if the toe-side cluster is blocked. The investigation provides a rational and feasible method for operators to understand proppant transport between clusters and optimize pumping parameters under field situations.

Proppant transport in secondary Sand fracturing using Eulerian-Eulerian multiphase model Approach

Secondary sand fracturing, an innovative hydraulic fracturing technique, divides the injection of proppant into two stages, altering the reservoir's rock mechanics and fracturing fluid flow paths, thus effectively controlling fracture creation and improving the effectiveness of proppant placement. This methodology facilitates fracture height control and enhances fracture conductivity, benefiting production rate. Despite abundant literature on proppant transport, limited attention has been paid to exploring the specific aspects of secondary sand fracturing. In this study, the Eulerian-Eulerian multiphase model was used to simulate the proppant transport in secondary sand fracturing for the first time. This model accounts for turbulence and the interplay between proppant particles, thus enabling a comprehensive integration of fluid and particulate phases. The effects of proppant performance, fracturing fluid performance, and fluid flow rate on proppant placement were analyzed. In the first sand-addition stage, an innovative sanding index was proposed to evaluate the effectiveness of proppant placement. Combined with the orthogonal experiment, the fluid flow rate significantly influences proppant placement. An escalated flow rate augments both the sandbank leading edge and laying lengths, concurrently diminishing the equilibrium height and the sanding index. In the second sand-addition stage, the equilibrium height increases with the increase of sand ratio, decreases with the increase of flow rate and fluid viscosity, and first increases and then decreases with the increase of particle size and proppant density. This study enriches the comprehension of proppant placement and its governing elements within hydraulic fracturing, thereby furnishing a more empirical and theoretically sound foundation for optimizing secondary sand fracturing practices.

New experimental model to evaluate the effect of negative pressure wound therapy and viscosity exudates in foam dressings using confocal microscopy.

Negative pressure wound therapy is currently one of the most popular treatment approaches that provide a series of benefits to facilitate healing, including increased local blood perfusion with reduced localized oedema and control of wound exudate. The porous foam dressing is a critical element in the application of this therapy and its choice is based on its ability to manage exudate. Industry standards often employ aqueous solutions devoid of proteins to assess dressing performance. However, such standardized tests fail to capture the intricate dynamics of real wounds, oversimplifying the evaluation process. This study aims to evaluate the technical characteristics of two different commercial polyurethane foam dressings during negative pressure wound therapy. We introduce an innovative experimental model designed to evaluate the effects of this therapy on foam dressings in the presence of viscous exudates. Our findings reveal a proportional increase in dressing fibre occupancy as pressure intensifies, leading to a reduction in dressing pore size. The tests underscore the pressure system's diminished efficacy in fluid extraction with increasing fluid viscosity. Our discussion points to the need of establishing standardized guidelines for foam dressing selection based on pore size and the necessity of incorporating real biological exudates into industrial standards.

Numerical Simulation of Hydraulic Fracture Propagation on Multilayered Formation Using Limited Entry Fracturing Technique

Hydraulic fracturing is one of the most effective stimulation methods for unconsolidated sandstone reservoirs. However, the design of hydraulic fracturing must take into account the mechanical and stress properties of different geological formations between layers. In this paper, a three-dimensional coupled fluid-solid model using the finite element method is developed to investigate multiple vertical fractures at different depths along a vertical wellbore under different geological and geomechanical conditions. The finite element model does not require further refinement of any new cracks, requiring much smaller degrees of freedom and higher computational efficiency. In addition, new elements were used to account for local pressure drop due to perforation entry friction along the vertical wellbore. Numerical simulation results indicate that hydraulic fracture connections are observed from adjacent layers. Furthermore, the low stress contrast and high Young’s modulus between the layers increases the likelihood of multiple fracture connections. Higher fluid leakage rates increase the likelihood of fracture branching, but decrease the area of fracture coverage near the wellbore. Increasing fluid viscosity is effective in improving the area of fracture coverage near the wellbore. These findings are useful for the design of hydraulic fracturing in multi-layered formations in unconsolidated sandstone formations.

Assessment of viscosity effects on high-speed coolant pump performance

The high-speed coolant pump facilitates thermal regulation in electric vehicle components, including batteries and motors, by circulating an ethylene glycol solution. This commonly used circulating fluid exhibits a notable negative correlation with temperature in terms of viscosity. Numerical simulations investigate the transient dynamics of a high-speed coolant pump operating at 6000 rpm, driving coolant flow at various temperatures. A high-speed coolant pump test rig is established, and the performance is evaluated under different temperature conditions. The numerical simulations at different temperatures align well with the experimental outcomes. Decreasing temperatures, from 100 to −20 °C, lead to reduced pump head and efficiency due to increased viscosity. Specifically, at a flow rate of 30 L/min, head decreases by 40.03% and efficiency by 44.19%. With escalating viscosity, the best efficiency point shifts toward lower flow rates. Notable impacts on both disk efficiency and hydraulic efficiency are observed due to viscosity fluctuations. It exerts minimal influence on volumetric efficiency at elevated flow rates but has a substantial impact on volumetric efficiency at lower flow rates. Increased fluid viscosity causes uneven pressure distribution within the pump, altering velocity profiles within the impeller. High-viscosity fluids tend to form large-scale vortex structures around the blades, reducing the thrust exerted by the blades on the fluid. Higher viscosity results in larger vortex structures around the blades, reducing thrust and increasing fluid frictional resistance. The study findings provide valuable insights for the advancement of high-efficiency, energy-saving, high-speed coolant pumps tailored for electric vehicles.

Increasing Fluid Viscosity Ensures Consistent Single-Cell Encapsulation.

High-throughput single-cell analysis typically relies on the isolation of cells of interest in separate compartments for subsequent phenotypic or genotypic characterization. Using microfluidics, this is achieved by isolating individual cells in microdroplets or microwells. However, due to cell-to-cell variability in size, shape, and density, the cell capture efficiencies may vary significantly. This variability can negatively impact the measurements and introduce undesirable artifacts when trying to isolate and characterize heterogeneous cell populations. In this study, we show that single-cell isolation biases in microfluidics can be circumvented by increasing the viscosity of fluids in which cells are dispersed. At a viscosity of 40-50 cP (cP), the cell sedimentation is effectively reduced, resulting in a steady cell flow inside the microfluidics chip and consistent encapsulation in water-in-oil droplets over extended periods of time. This approach allows nearly all cells in a sample to be isolated with the same efficiency, irrespective of their type. Our results show that increased fluid viscosity, rather than cell-adjusted density, provides a more reliable approach to mitigate single-cell isolation biases.

Numerical simulation and experimental study of hole cleaning

Insufficient hole cleaning causes tool wear and reduces drilling efficiency. Existing evaluation methods and models are limited. In this study, a universal method is proposed to assess hole cleaning efficiency (HCE). A coupled computational fluid dynamics and discrete element method (CFD-DEM) numerical model for non-Newtonian fluid simulation of cuttings transport is developed. The influence of various factors on HCE was analyzed from an energy and particle collision perspective, with a particular focus on the mechanisms of fluid viscosity and rate of penetration (ROP) on cuttings settling. Results show that increased fluid viscosity improves HCE, while excessive viscosity negatively affects it. Higher ROP results in increased solid particle concentration and collision probability, leading to energy loss and reduced efficiency. Lower HCE was observed when the inclination deviated from the vertical. The HCE can be significantly improved by increasing the fluid velocity and reducing the eccentricity. A comprehensive prediction model for HCE is established using Design of Experiment (DOE), dimensional analysis, and nonlinear regression. This model incorporates a generalized fluid apparent viscosity, taking into account the impact of each rheological parameter. Additionally, it can be applied to predict hole cleanliness in both Newtonian and non-Newtonian fluids. By comparing the experimental results of hole cleanliness in three distinct fluids, the regression model yielded reliable predictive results. The findings enhance understanding regarding how fluid properties and the ROP affect cuttings transport and enable precise and convenient prediction and optimization of hole cleaning efficiency.

Effects of MHD and thermal radiation on non-Newtonian fluid with Cattaneo–Christov heat over a stretching flow surface

In this study, we are investigating the flow of an incompressible Williamson fluid using a Cattaneo–Christov heat flux model, with consideration for a magnetic Reynolds number that is not high. This fluid flows over a linearly stretched 2-D surface and is affected by a magnetic field, thermal radiation-diffusion, and heat generation. To model the Williamson flow, we apply a boundary layer approximation and develop the ordinary differential equations. The system of differential equations is transformed into a system of ordinary differential equations using a suitable transformation. We utilize the Iterative Runge–Kutta fourth-order scheme to numerically solve the boundary conditions associated with the nonlinear, dimensionless ordinary differential equations. Graphical representations of the results are employed to analyze the impact of physical properties on velocity, temperature, and concentration, with the numerical results presented in tabular form. Upon comparing our findings with previously published results, we have found them to be in good agreement. The velocity decreases as the Williamson fluid factor gradually increases. Williamson fluids are recognized for their shear thinning behavior, wherein viscosity decreases as the shear rate increases. However, higher parameter values can lead to increased fluid viscosity, potentially reducing the degree of shear thinning. This phenomenon results in a more uniform viscosity profile across varying shear rates, contributing to a reduced velocity distribution within the fluid.

Experimental study on the dissolution characteristics of ethane into oil‐based mud in complex oil and gas wellbore environments

AbstractAccurately determining the solubility of ethane in oil‐based mud is crucial for assessing the severity of gas kicks and implementing appropriate well control procedures. The key factors influencing the solubility of ethane gas in oil‐based drilling fluids include the content of base oil, pressure, temperature, and the viscosity of the drilling fluid. This study aims to test the solubility of high‐purity ethane in oil‐based mud under simulated downhole conditions in a 5000 m deep well. The test covers a temperature range of 40–140°C and a partial pressure range of 0.17–5.92 MPa. The effects of temperature, pressure, base oil content, and drilling fluid viscosity on the solubility of ethane are analyzed using various experimental data processing methods. The results show that the variation in ethane solubility with pressure and temperature is nearly linear within the specified ranges. Furthermore, the impact of pressure (1.24–2.78%/MPa) on solubility is approximately 50 times greater than that of temperature (−0.013 to −0.049%/°C) in oil‐based drilling mud. Additionally, ethane's solubility decreases as the drilling fluid's viscosity increases. The ethane solubility in 80% and 90% oil‐based muds is roughly 1.6 times and 2.0 times higher than in 70% oil‐based mud under the same testing conditions. Models for predicting ethane solubility have been developed using screening procedures and statistical regression. These models can be incorporated into gas–liquid flow models to analyze flow behavior during gas kicks.

Numerical simulation of multi-fracture uniform propagation in naturally fractured reservoirs based on the continuum–discontinuum method

Multi-cluster fracturing technology with horizontal wells is significant for the production enhancement of unconventional reservoirs. However, affected by the natural fracture distribution in the reservoir, stress shadowing between multi-fractures and perforation erosion has non-negligible influence on the multi-fracture uniform propagation, which results in uneven reservoir stimulation and lower production capacity. In this study, a multi-field coupled stress-seepage-fracture model for hydraulic fracturing of fractured reservoirs based on the continuum–discontinuum method was developed, adequately simulating the full scenario of stress disturbances, perforation erosion, and fracture interactions during the fracturing process. The effect of different geological and engineering parameters on the competing propagation of multi-fractures was investigated in detail, and the results show: Different geological and engineering parameters have significant influence on the competitive propagation of multi-fractures; among the geological parameters, the elastic modulus has the highest impact on the uniform fluid intake of multi-fractures, while the horizontal stress difference has the least impact on the uniform fluid intake of multi-fractures. Among the engineering parameters, the effect of natural fracture angle on the standard deviation of the fluid injection volume is gradually reduced with the increase in perforation number, flow rate, and fluid viscosity. For a low number of perforations and high fluid viscosity, both have great influence on promoting uniform fluid entry in multiple fractures. In addition, geological parameters have a significantly greater influence on the merging of multi-fractures than engineering parameters, and the probability of merging of multi-fractures increases significantly under low stress differentials and long natural fractures.

Stagnant points and uniform film analysis of Eyring fluid film flow on a vertically upward moving slippery flat plate

In this paper, we analyze how Eyring fluid film behavior on a vertically upward moving slippery flat plate can help predictive models in engineering, notably in coating and lubrication operations. This paper deals with the stagnant points and uniform film analysis of Eyring fluid film flow on a vertically upward moving slippery flat plate. The formulated ordinary differential equation is solved for exact analytic solution. Exact analytic expressions for velocity, flow rate, average velocity, shear stress components, and stagnant points are derived. A highly nonlinear algebraic equation is derived for film thickness. Equation is solved by Newton’s method using Maple code. The thickness of film widens with increasing relaxation time, constant plate velocity, and fluid density, while it decreases with increasing fluid viscosity and constant slip parameter. The analysis delineates that the positions of stagnant points tend to relocate closer the slippery plate as the Stokes number, Deborah number, and constant slip parameter increase. A high Deborah number enhances drainage, causing stagnant points to relocate closer to the slippery plate and the development of a stable elastic layer adjacent to the plate. For stagnant points and fluid film thickness, a comparison between the Eyring fluid and existing studies (EPTT, LPTT, UCM, and Newtonian fluid) is also provided. The validity of this paper with the existing studies is also presented by reducing Eyring fluid model to Newtonian model. The results of this research are significant for a wide range of biofluid applications, including agrochemical uses, paint and surface coating flow behavior, thin films on the cornea and lungs, and chemical and nuclear reactor design.

Liquid plug propagation in computer-controlled microfluidic airway-on-a-chip with semi-circular microchannels.

This paper introduces a two-inlet, one-outlet lung-on-a-chip device with semi-circular cross-section microchannels and computer-controlled fluidic switching that enables a broader systematic investigation of liquid plug dynamics in a manner relevant to the distal airways. A leak-proof bonding protocol for micro-milled devices facilitates channel bonding and culture of confluent primary small airway epithelial cells. Production of liquid plugs with computer-controlled inlet channel valving and just one outlet allows more stable long-term plug generation and propagation compared to previous designs. The system also captures both plug speed and length as well as pressure drop concurrently. In one demonstration, the system reproducibly generates surfactant-containing liquid plugs, a challenging process due to lower surface tension that makes the plug formation less stable. The addition of surfactant decreases the pressure required to initiate plug propagation, a potentially significant effect in diseases where surfactant in the airways is absent or dysfunctional. Next, the device recapitulates the effect of increasing fluid viscosity, a challenging analysis due to higher resistance of viscous fluids that makes plug formation and propagation more difficult particularly in airway-relevant length scales. Experimental results show that increased fluid viscosity decreases plug propagation speed for a given air flow rate. These findings are supplemented by computational modeling of viscous plug propagation that demonstrates increased plug propagation time, increased maximum wall shear stress, and greater pressure differentials in more viscous conditions of plug propagation. These results match physiology as mucus viscosity is increased in various obstructive lung diseases where it is known that respiratory mechanics can be compromised due to mucus plugging of the distal airways. Finally, experiments evaluate the effect of channel geometry on primary human small airway epithelial cell injury in this lung-on-a-chip. There is more injury in the middle of the channel relative to the edges highlighting the role of channel shape, a physiologically relevant parameter as airway cross-sectional geometry can also be non-circular. In sum, this paper describes a system that pushes the device limits with regards to the types of liquid plugs that can be stably generated for studies of distal airway fluid mechanical injury.

Research on the influence of fluid viscosity on the inlet flow parameters of wiped film molecular distillation

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.

Evaluation of erosion of AISI 1045 carbon steel due to non-cohesive microparticles

Erosion behavior of AISI 1045 carbon steel was investigated using slurry solutions with different viscosities (1 cP, 3 cP, and 8 cP) containing 5 wt% silica sand as erodent particles. Tests were carried out using a slurry pot apparatus with various rotational velocities and at three mounting angles (30°, 60°, and 90°). The qualitative and quantitative analysis was performed using the Taguchi design method, paint modeling, image processing, and microscopic imaging techniques. The results indicate that the erosion process in the slurry flow is significantly influenced by fluid viscosity. There is a notable decrease in erosion wear rate as fluid viscosity increases. An analysis of variance (ANOVA) test was conducted, concluding that viscosity and rotational speed are the significant factors influencing the weight loss of carbon steel. The results demonstrate that each factor has a major impact on the response; velocity (47.20 %) is the primary factor contributing to R, followed by viscosity (38.20 %). The erosive wear mechanism changed considerably with the variation in fluid viscosity and impact angles. As viscosity increases, the cutting and pitting erosion wear mechanism shift to sliding wear with the development of micro-perforation sites.

Elastic Wave Mechanics in Damaged Metallic Plates

Human health monitoring (HHM) is essential for continued daily task execution, as is structural health monitoring (SHM) for structures to ensure the continual performance of their designed tasks with optimal efficiency. The existence of damage in a structure affects its optimal use through stiffness deterioration. Damage of different forms could occur in a structure but have the singular objective of material degradation, leading to its underuse for a task. Guided wave ultrasonics has shown strength in detecting sundry damage in structures, but most of the damage monitored and detected is unfilled with substances. However, some damage could trap and accumulate substances that could hasten material degradation through corrosion activities under favorable conditions, especially in the oil and gas industry. This study used the ultrasonic-guided waves’ pitch–catch inspection technique to identify damage filled with different materials. The assessment was based on the RMSD of the dominant Lamb wave mode’s average maximum amplitude and the response signals’ transmission coefficient (TC). A five-cycle tone burst of excitation signals of different frequencies was created to generate propagating Lamb waves in the structure. The fundamental antisymmetric mode was found to be more sensitive than the fundamental symmetric mode when detecting damage filled with various substances. At 80 kHz, the deviation of the current response signals from the baseline response signals due to different filled substances in the damage was distinct and decreased with increased fluid viscosity. Given that structures in the oil and gas sector are particularly susceptible to substance-induced damage, the outcomes of this study are paramount.

Experimental study of fluid-particle flow characteristics in a rough fracture

Rough fractures can significantly affect particle-fluid flow in a stratum, but particle transport characteristics are still not fully understood. This paper proposes a novel method to combine three-dimensional laser scanning and casting technology for making rough transparent panels based on rock fractures. A large model with two-sided rough surfaces is constructed, and the inner sizes are 2 m × 0.3 m × 3 mm. The particle image velocimetry method is used to analyze slurry flow. The experimental results show that distorted irregular streamlines, vortexes, sand settling, and dispersion are primary characteristics of particles transported by low-viscosity fluid. Shear flow can induce prominent vortexes around the inlet and the fracture top. With the increase in fluid viscosity, sand-fluid flow along preferential flow paths, and particle clusters are easily formed due to sand aggregation in tortuous pathways. Increasing the fluid velocity avoids particles plugging around the inlet, and there is a threshold velocity. The vortex number has a negative relationship with fluid viscosity. With the dune accumulation, the vorticity intensity is significantly increased, and discrete vortexes are connected into a large vorticity region, which collapses sand aggregation along the whole fracture. Increasing fluid velocity and viscosity and reducing particle diameter are more effective ways to improve particle distribution than increasing particle concentration. The combination of multiple factors can enhance the more even distribution of particles in rough fractures. The investigation provides a fundamental understanding of slurry flow behaviors in fractured media and is a valuable reference for the simulation of particle-fluid flow.

Effect of fluid viscosity on the biomechanical sequence of oropharyngeal swallowing in healthy males

Objective: To confirm the effect of fluid with different viscosity on the normal biomechanical sequence of oropharyngeal swallowing in healthy males. Methods: Fifteen healthy male subjects [(27.7±1.8) years old] were recruited from November 2011 to February 2012 and instructed to swallow 15 ml of water (W), nectar-like fluid (N), and honey-like fluid (H) in an upright sitting position. The sensing system was consisted of tongue pressure sensor sheet, bend sensor, surface electrodes and microphone. They were used to monitor tongue pressure, hyoid activity, surface electromyography (EMG) of swallowing-related muscles and swallowing sound, respectively. The swallowing sound was chosen as the reference time. The significance of biomechanical sequence of structural events was determined by repeated-measures analysis of variance (ANOVA). Results: When swallowing liquid of any consistency, hyoid premotor and suprahyoid muscle electromyography (EMG) appeared synchronously (P>0.05), followed by the simultaneous appearances of hyoid rapid movement, peak time of suprahyoid muscle EMG, onset of infrahyoid muscle EMG, and anterior tongue pressure production (P>0.05). The peak time of infrahyoid muscle EMG was very close to the peak time of anterior tongue pressure (P>0.05), and both of them were earlier than the time that the hyoid reaching the highest position (P<0.05). At last, the time that the hyoid departing the highest position was synchronized with the disappearances of suprahyoid muscle EMG, infrahyoid muscle EMG, and tongue pressure (P>0.05). The tongue pressure production and peak time of tongue pressure arose from anterior to posterior along the midline of hard palate during normal swallowing, with the significances for tongue pressure production between the anterior site and the middle site (W: P=0.035, N: P=0.027, H: P=0.013) as well as the anterior site and the posterior site (W: P<0.001, N: P<0.001, H: P<0.001), while the appearance and peak time of the circumferential tongue pressure were very close (P>0.05). The increase of fluid viscosity did not affect the biomechanical sequence of the above structural physiological movements during normal swallowing. There were statistically significant differences between the hyoid premotor and the onset of suprahyoid muscle EMG when swallowing the honey-like liquid [(-1.03±0.47) and (-0.90±0.50) s] and water[(-0.87±0.32) and (-0.74±0.31) s] (P<0.001). Among the delayed structural events, except for the onset of infrahyoid muscle EMG and the tongue pressure production on the anterior site (P>0.05), the occurrences of all the parameters in swallowing honey-like fluid were significantly later than those in swallowing water (onset of hyoid rapid movement, P=0.007; time of hyoid reaching the highest position, P=0.034; time of hyoid departing the highest position, P=0.041; offset of hyoid movement, P=0.035; peak time of suprahyoid muscle EMG: P=0.040; offset of suprahyoid muscle EMG, P=0.014; peak time of infrahyoid muscle EMG: P=0.042; offset of infrahyoid muscle EMG, P=0.028; peak time of Ch.1: P=0.045; offset of Ch.1: P=0.012; onset of Ch.2: P=0.038; peak time of Ch.2: P=0.009; offset of Ch.2: P=0.034; onset of Ch.3: P=0.043; peak time of Ch.3: P=0.011; offset of Ch.3: P=0.026;onset of Ch.4: P=0.040; peak time of Ch.4: P=0.038; offset of Ch.4: P=0.033; onset of Ch.5: P=0.046; peak time of Ch.5:P=0.028; offset of Ch.5: P<0.001), but not for those between nectar-like fluid and honey-like fluid (P>0.05). Conclusions: The alteration of fluid viscosity did not affect healthy male biomechanical sequence of tongue, hyoid and swallowing-related muscles during normal swallowing. The biomechanics of the oropharyngeal structures is physiologically regulated with the alteration of fluid viscosity to ensure swallowing safely and smoothly.

Atomization of High Viscous Liquids Using a MEMS Vibrating Mesh With Integrated Microheater

Aerosol generation is important for a wide range of applications including drug delivery, additive manufacturing, spray cooling, and numerous other applications. However, current aerosol generation devices often have poor droplet uniformity or are limited to low viscosity liquids ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 2 cp). This work presents the development of a Microelectromechanical systems vibrating mesh atomizer capable of atomizing higher viscosity fluids while maintaining high droplet size uniformity. The overall system consists of microfabricated silicon vibrating mesh atomizer, a piezoelectric film, and a flexible thin film microheater. The Si vibrating mesh atomizer was designed to increase atomization thresholds, while the microheater is designed to reduce liquid viscosity to meet the atomization threshold. Atomizers with varying nozzle dimensions were experimentally validated using liquids with varying viscosity and physiochemical properties, such as water, glycerol, propylene glycol, and vegetable glycerin. The microheater was designed to provide local rapid heating with low power consumption of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 1 W. The droplet size distribution results show that when fluid viscosity increases, the volume median diameter of droplets increases, and the spray angle decreases. The Si-vibrating mesh atomizer was able to atomize liquids up to 49.73 cP at room temperature compared to normal metallic vibrating mesh atomizers which have a threshold of approximately 2 cP. The integrated heater enabled atomization of liquids with viscosities as high as 111 cP with low heating ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 100 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> C). 2023-0042