Impact Of Suction Research Articles

Critical state behaviour of an unsaturated kaolin mixture

In this paper, a series of suction-controlled triaxial tests were conducted to investigate the hydromechanical behaviour of an unsaturated kaolin mixture. The studied variables included the mean net stress, suction, and initial dry density. The suction was controlled over a wide range – in the span of 0–390 MPa using the axis translation method and the vapour equilibrium technique, aiming to holistically study the mechanical response of unsaturated soils. The discussion focused on the critical state behaviour and dilatancy characteristics of the tested soil. The experimental results indicate that the ductility of the soil decreases and shifts towards brittleness with increasing suctions. The critical state stress ratio (Ma) of the soil exhibits a significant increase with suction, and this increase becomes more pronounced with higher initial dry density. Conversely, the impact of suction on the critical state line in the specific volume-mean net stress plane (v-lnpnet plane) diminishes with higher initial dry density. Furthermore, suction notably influences the stress-dilatancy relationship of kaolin mixtures, while the effect of confining pressure appears to be marginal. The influence of suction on the stress-dilatancy relationship primarily stems from its impact on the critical stress ratio (Ma), which can be normalized by dividing the stress ratio by the critical state stress ratio. Lastly, the stress-dilatancy equation of the modified Cam-clay model is extended to capture the effect of suction on the dilatancy characteristics of unsaturated soils.

Suction impact on Eyring Powell nanofluid flow over an electromagnetic medium with Joule heating

The current study has addressed numerically the importance of blowing and suction outcomes on Eyring-Powell nanofluid flow over an electromagnetic surface with heat generation, activation energy and Joule heating. Through the use of similarity conversions, the governing equations are changed to the level of a collection of nonlinear ODEs. In order to solve the nondimensional ODEs under physically realistic boundary circumstances, the bvp4c variational method has been used. The flow velocity computed numerically compares well to the precise solution presented in the literature. The results of numerical calculations have made this very evident. The graphical patterns were displayed to explore the effects of near-surface tangible parameters and engineering factors on the significant physical flow features. The results indicate that the velocity of the nanofluid decreases as the suction and magnetic parameters rise in value. A comparison is made between the current findings and the results that have been obtained in the past, and it is discovered that there is a good agreement between the results.

Impact of suction with nanoparticles aggregation and joule heating on unsteady MHD stagnation point flow of nanofluids over horizontal cylinder

Significance of studyNanofluids with aggregation effects mediated by nanoparticles, like geothermal panels and crossflow heat exchangers, ignite new industrial interests. Polymer and conversion processes have transport phenomena in the stagnation zone that must be continuously improved to raise the process quality standard. Aim of studyHence, the current computational study examines a TiO2−C2H6O2 nanofluid's unsteady stagnation-point flow performance via a shrinking horizontal cylinder. In addition, the effects of a magnetic field, joule-heating viscous dissipation, nanoparticles aggregation and mass suction on the boundary layer flow are reflected. Methodology: The RK-IV with shooting method is applied to resolve the simplified mathematical model numerically in computing software MATHEMATICA. In certain circumstances, comparing the current and prior findings indicates good agreement with a relative error of around 0%. FindingsThe implementation of a heat transfer operation may be improved by increasing suction settings. Unsteadiness, nanoparticle volume fraction, magnetic, curvature, and Eckert number (implies the operating Joule heating and viscous dissipation) all influence heat transfer rate. The velocity and temperature profiles both increase as the unsteadiness, magnetic field, and nanoparticle volume fraction parameters increase, whereas the curvature and suction parameters show the opposite behavior. When the values of the suction parameters were changed from 2.0 to 2.5 with φ = 0.01, the heat transfer rates rose by 4.751%. A comparison shows that the model with aggregation has a better velocity profile, while the model without aggregation has a better temperature profile.

Numerical analysis of ternary hybrid nanofluid flow over a stagnation region of stretching/shrinking curved surface with suction and Lorentz force

In recent years, there has been a lot of interest in studying stagnation point flow. This is because stagnation point flow is used in many technological applications, such as cooling spinning machinery segments and nuclear reactors. This study analyzes the potential practical applications of the ternary (Cu-Fe3O4-SiO2/SA) hybrid nanofluid as it flows through a stagnation zone of a stretching or shrinking curved surface under the impact of suction and Lorentz force. To acquire numerical solutions, the governing PDEs are first altered into a system of ODEs and then entered into the MATHEMATICA program. We compare findings for validation purposes and illustrate the consequences of specific characteristics that will be planned for the physical quantities that are of interest. When magnetic field and suction are present, velocity improves, but the inverse is true for curvature and nanoparticle volume fraction for both stretching and shrinking surfaces. Temperature increases against nanoparticle volume fraction, magnetic field, and heat source/sink and decreases against suction and curvature parameters for both stretching and shrinking cases. When the values of the suction parameters were changed from 2.0 to 2.5, the heat transfer rates rose by an increase ranging from 34% to 39% may be determined. Improved velocity and temperature distributions may be attributed to the presence of ternary hybrid nanofluids. This research gives scientists and engineers a head start in adjusting the relevant parameters to get the best possible results in the associated practical applications.

Statistical Analysis of Non-Newtonian Couple Stress Fluid Induced in Stretching Cylinder

The paper provides the impact of suction and injection on convection laminar incompressible couple stress fluid flow and magnetic field using spectral quasi linearization methods as the major novelty of our work. This work is to addresed heat transfer is an important process in many engineering, industrial, residential, and commercial buildings. Thus, this study aims to analyze the effect of MHD and non-Newtonian couple stress fluid runs over a permeable stretched cylinder. The leading formulation is transmuted into ordinary differential equations via similarity functions. The coupled equations with non-linearly terms are resolved numerically through utilization of MATLAB code for spectal quasi linearization methods (SQLM). Convergence regions for solutions are discussed. Graphical results illustrating the impacts of various emerging parameters are presented in discussion. The statistical declaration and probable error for skin friction and Nusselt number are numerically computed and discussed through Tables. From obtained outcomes it is concluded that magnitude of skin friction increases at the cylindrical surface for higher values of couple stress parameter and Reynolds number. Nusselt number or heat transfer rate also enhances at the surface of cylinder in the presence of Reynolds number.

Impact of Suction on the Near Surface Lateral Soil Response using Centrifuge Modeling

Recent studies have shown that unsaturated soils lead to greater lateral pile capacity. This study aims to experimentally assess how suction stress affects the lateral response of piles in unsaturated cohesionless soil. Two centrifuge tests were performed at 50 g to evaluate the effect of suction stress in the soil. Lateral loads were applied monotonically on a single free-head pile in a displacement-controlledmanner to a maximum pile head displacement of 0.44 m. The first test was conducted on fully saturated cohesionless soil, while the second test was performed in an unsaturated state with a mixed unsaturatedsaturated soil layer. The water table was lowered to about 0.12 times the embedded pile depth to ensure an unsaturated condition in the zone closer to the surface of the soil. Lateral response assessment indicates that the unsaturated soil influenced the pile head response, leading to larger applied lateral loads for similar pile displacements in comparison to the fully saturated soil test. Experimental findings reveal that suction stress played a meaningful role in magnitudes of pile bending moments and lateral resistances for unsaturated cohesionless soils.

Kinematic limit analysis of unsaturated stepped excavation slopes under surcharge loads

Stability assessments and design of stepped excavation slopes are of great practical significance and require explicit consideration of the three-dimensional (3D) effect and suction-related effects. In the realm of 3D kinematic limit analysis, this paper presents a semi-analytical method to quantify the impact of suction in stability assessments of stepped excavation slopes. The influences of surcharge load and seismic excitation are both considered from a kinematic perspective. Numerical experiments were conducted regarding the roles of soil suction, 3D effects, surcharge loads and seismic actions in safety assessments. An example is presented to show the practical use of the proposed method in engineering practice with respect to determination of the optimum shape of a stepped excavation slope characterised with a fixed slope toe and slope crest positions. The results demonstrate that the stability of stepped excavation slopes can be improved by 10–25% compared with the stability of a single-stage slope and the optimum depth coefficient (αopt) falls in the range 0.55–0.70 in most cases. For steeper excavation slopes, αopt might exceed this range while, for gentler slopes, αopt tends to be smaller than this range. The critical slip surface and 3D effects tend to be more pronounced with an increase in surcharge load.

Three Dimensional MHD Hybrid Nanofluid Flow with Rotating Stretching/Shrinking Sheet and Joule Heating

A three-dimensional hybrid nanofluid flow over a stretching/shrinking sheet is numerically studied. The hybrid nanofluid being considered in this study used water as the base fluid and mixed with two types of solid nanoparticles, namely alumina (Al2O3) and copper (Cu). The main focus of the current study is to examine the effect of magnetic field, Joule heating, and rotating sheet on the velocity, and temperature profiles. In addition, the impact of suction and stretching sheet on the variations of reduced skin friction, , and reduced heat transfer are studied as well. The fluid flow and heat transfer problem presented in this study is governed by a system of nonlinear partial differential equations (PDEs), which is then transformed into the corresponding system of high order nonlinear ordinary differential equations (ODEs) using similarity variables. The resulting system of higher order nonlinear ODEs is solved numerically using a boundary value solver known as bvp4c, which operates on the MATLAB computational platform. Results revealed that dual solutions exist for shrinking sheet while unique solutions are observed for stretching sheet with various values of Cu nanoparticles volume fraction and magnetic parameter. Dual solutions also exist for the value of the suction parameter greater than its critical point with various values of Cu nanoparticles volume fraction. Velocity profile of the hybrid nanofluid increases alongside with the value of magnetic parameter but declination was observed in the profile of and temperature, for both solutions as the value of Cu nanoparticles volume fraction increases. When the value of rotational parameter increases, both velocity and profiles increase for both solutions. This indicates that the momentum boundary layer thickness increases with increasing values of for both solutions, but thermal boundary layer thickness decreases for the first solution and increases for the second solution. Finally, an increment in the value of Eckert number causes the temperature of the hybrid nanofluid to rise as well for both first and second solutions.

Simulation and Measurement of Aerosolisation in Different Chest Drainage Systems

The aim of the study was to assess the degree of aerosolisation in different chest drainage systems according to different air leak volumes, in a simulated environment. This novel simulation model was designed to produce an air leak by passing air through and agitating a fluorescent fluid. The air leak volume and amount of fluorescent fluid were tested in various combinations and aerosolisation was assessed at 10-minute intervals using the ultraviolet light. The following chest drainage systems were compared: (1) single-chamber chest drainage system, (2) 3-compartment wet-dry suction chest drainage system, (3) digital drainage and monitoring system. The impact of suction (−2 and −4 kPa) in generating aerosolised particles was tested as well. A total number of 187 of 10-minute interval measurements were performed. The single-chamber chest drainage system generated the largest number of aerosolised particles at different air leak volumes and drainage output. The 3-compartment wet-dry suction system and the digital drainage and monitoring system did not generate any identifiable aerosolised particles at any of the air leak or drain output volumes considered. Suction applied to the chest drainage systems did not have an effect on aerosolisation. Aerosol generation in the simulated air-leak model demonstrated the potential risk of SARS-CoV-2 spread in the clinical setting. Full personal protective equipment must be used in patients with an air leak. Single-chamber chest drainage system generates the highest rate of aerosolised particles and it should not be used as an open system in patients with an air leak.

Impact of Suction in the EUS-guided Fine Needle Biopsy of Solid Pancreatic Lesions

Impact of Suction in the EUS-guided Fine Needle Biopsy of Solid Pancreatic Lesions

The Impact of Suction- Assisted Laryngoscopy and Airway Decontamination on Intubation Times

The Impact of Suction- Assisted Laryngoscopy and Airway Decontamination on Intubation Times

Modelling the poroplastic damageable behaviour of earthen materials

This paper presents a new constitutive model on the poroplastic behaviour of earthen materials accounting for stiffness degradation, using the approach of continuum damage mechanics. The poroplastic behaviour is modelled based on the bounding surface plasticity (BSP) theory and the concept of effective stress while isotropic damage is modelled using a scalar variable. Plastic flow and damage evolution occur simultaneously in a coupled process which take into account the impact of suction. The model was successfully validated against results of triaxial compression tests performed at different relative humidities and confining pressures. Despite the relatively small number of material parameters, this model can reproduce the essential features of earthen materials behaviour observed experimentally: suction-induced hardening and stiffening, post-peak softening, as well as the progressive transition from contractant to dilatant volumetric behaviour. Use of the BSP theory allows to reproduce a smooth stress–strain relation as experimentally observed, instead of an abrupt change upon plastic yielding predicted by classic elastoplastic models. Furthermore, the present model also furnishes a quantitative description on the degradation of elastic properties hitherto not accounted for, thanks to the additional scalar damage variable.

Understanding effects of process parameters and forced feeding on die filling

Die filling is a critical step during pharmaceutical tablet production and is still not well understood due to the rather complex interplay between particle attributes, die orifice diameter and fill energetics. While shoe-die filling models have been used to simulate die filling conditions, they typically lack the sophistication of the actual production-scale, feeder-based die filling conditions. The relationship between tableting process parameters and filling into die orifices of different diameters by powders of different flowabilities requires critical examination and understanding. In this study, a special die filling contraption was designed and custom-made to simulate the effects of gravity, suction and feeder paddle assistance as present in modern rotary tablet presses. Die fill performance was studied using powders with different flow properties. Suction impact was greatest on die fill, in particular, for small orifice diameters and less permeable powders. Effect of paddle velocity on die fill was greater for compressible powders and larger orifice diameters. In comparison to suction and paddle velocity, forced feeding did not significantly affect die fill performance. Relationship between process parameters and die fill performance was found to be highly dependent on the material and orifice diameter.

Boundary layer suction through rectangular orifices: effects of aspect ratio and orientation

The flow field generated by suction through a rectangular orifice within a laminar boundary layer is investigated using stereoscopic particle image velocimetry. For orifice aspect ratios of 6, 12, and 18, the impact of suction on the surrounding flow field appears to be self-similar, scaling with aspect ratio and suction velocity. Changing the orifice pitch angle had almost no impact on the surrounding boundary layer, but, as expected, changing the skew angle significantly altered the extent of the suction impact on the flow field.

Yielding of Silt at High Temperature and Suction Magnitudes

This study presents an evaluation of yielding mechanisms for unsaturated, compacted silt using drained triaxial compression tests with control of elevated temperatures and high suction magnitudes. After anisotropic compression, some compacted silt specimens were heated by approximately 40 °C before a suction of approximately 300 MPa was applied, while others were heated after suction application. A frictional response was observed for the specimens sheared under high suction magnitudes, in the form of a consistent increase in peak shear strength with increasing net confining stress. An effective stress analysis was used to evaluate the trends in the peak shear stress and the role of stress history for the different specimens. A single peak failure envelope was observed when the shear strength data was interpreted in terms of the mean effective stress. Changes in preconsolidation stress were estimated by identifying the intersections between a thermo-elasto-plastic yield function and the experimental peak shear strength values. Soil specimens heated before application of high suction values had lower peak shear strengths than reference specimens at high suction and ambient temperature. This behaviour is consistent with thermal softening trends observed in soils heated under low suction values. However, soil specimens heated after suction application had greater peak shear strengths than the reference specimens. This indicates heating under high suction results in hardening. The impact of suction on the preconsolidation stress was found to be better represented by a power law model at high suction magnitudes than other available models. The estimated preconsolidation stress values were used to evaluate the impacts of stress history on the thermal volume change response, which matched well with data from tests on saturated specimens.

Stress and Fracture Analyses of Solar Silicon Wafers During Suction Process and Handling

Solar wafer/cell breakage depends on the combination of the stresses generated in the handling and the presence of structural defects such as cracks. Suction process is a common loading during silicon wafer handling. This paper presents a systematic static and dynamic analysis of the suction process. Optimum suction pad diameter and locations are obtained by minimizing the stress distribution under both static and dynamic loading, and the effect of the impact time on the crack driving force is also investigated in this optimum situation. The results show that the four pads configuration with diameter of 20 mm placed in a rhombus shape with 18 and 38 mm diagonal lengths yields lowest maximum principle stress among the cases analyzed. In the dynamic fracture analyses, the maximum J integral appears at 800 and 1400 μs for continued holding and unloading cases after reaching the maximum load, respectively. The J integral for the unloading cases are always smaller than the holding cases. It has been found that when the impact time is longer than 3 s and 5600 μs the dynamic fracture mechanics analysis of the suction impact process can be replaced by a static fracture mechanics analysis for the holding and unloading cases, respectively.

Influence of Matric Suction on the Stability of Unsaturated Slope

Matric suction plays a significant role in the unsaturated slope stability and receives a rising interest in how matric suction affects the unsaturated slope stability. According to the shear strength theories and soil-water characteristic curve of unsaturated soils，matric suction parameters were proposed to study the influences of matric suction on unsaturated slope stability by applying in strain-softening constitutive model and using catastrophe theory as a tool. The results show that the unsaturated slope safety factor depends on the stiffness ratio，the softening coefficient，the suction sensitive factor and the relative displacement ratio. However，when the system reaches the limit equilibrium circumstance，the fundamental factors particularly affecting the unsaturated slope stability are the stiffness ratio of two media and the softening coefficient of the sliding surface，and the further trend between matrix suction and unsaturated slope stability is the same as the changes of the suction impact factor.