Wall Thickness Parameter Research Articles

Design and performance study of bone trabecular scaffolds based on triply periodic minimal surface method

Triply periodic minimal surface (TPMS) is widely used because it can be used to control the shape of porous scaffolds precisely by formula. In this paper, an I-wrapped package (I-WP) type porous scaffolds were constructed. The finite element method was used to study the relationship between the wall thickness and period, the morphology and mechanical properties of the scaffolds, as well as to study the compression and fluid properties. It was found that the porosity of I-WP type scaffolds with different wall thicknesses (0.1 ~ 0.2 mm) and periods (I-WP 1 ~ I-WP 5) ranged from 68.01% ~ 96.48%, and the equivalent elastic modulus ranged from 0.655 ~ 18.602 GPa; the stress distribution of the scaffolds tended to be uniform with the increase of periods and wall thicknesses; the equivalent elastic modulus of the I-WP type scaffolds was basically unchanged after the topology optimization, and the permeability was improved by 52.3%. In conclusion, for the I-WP type scaffolds, the period parameter can be adjusted first, then the wall thickness parameter can be controlled. Topology optimization can be combined to meet the design requirements. The I-WP scaffolds constructed in this paper have good mechanical properties and meet the requirements of repairing human bone tissue, which may provide a new choice for the design of artificial bone trabecular scaffolds.

CHEMICALLY REACTIVE MHD FLOW THROUGH A SLENDERING STRETCHING SHEET SUBJECTED TO NON-LINEAR RADIATION FLOW OVER A LINEAR AND NON-LINEAR STRETCHING SHEET

In this analysis, the MHD flow and nth-order dispersion of chemically reactive species over a slendering stretching sheet are studied numerically. The partial slip boundary condition and non-linear form of thermal radiation are also considered in this research. To get non-linear ordinary differential equations from the system of partial differential equations governing the flow, energy, and concentration, similarity transformations are applied. Using the shooting technique and the Runge-Kutta scheme, the resultant equations are integrated numerically. The numerical results in terms of temperature, velocity, and concentration are represented graphically. Results from this research indicate that an increase in the wall thickness parameter reduces momentum and heat transfer effects when a magnetic field is present.

Multiple slips on Darcy–Forchheimer unsteady flow manifested with Cattaneo–Christov heat flux over a stretching sheet

This primary goal of this analysis is to investigate how several slips affect the flow, heat, and mass performance of Darcy–Forchheimer unstable behavior beyond a stretching sheet using a numerical analysis of the Soret effect. The novel constitutive model Cattaneo–Christov is illustrated to analyze the features of thermal relaxation time. The Cattaneo–Christov method is used to predict heat and mass transport. A surface that slanders and has varying thicknesses propels the flow. Through the use of local similarity transformations, the governing nonlinear partial differential equations reduce to the coupled ordinary differential equations and include the momentum, energy, and concentration equations. The altered ODEs are calculated numerically using the Runge–Kutta Fehlberg scheme and an efficient shooting procedure. The physical properties of the temperature, concentration, and fluid velocity profiles are shown visually and shed light on the change of several governing parameters. For example, in comparison to the classical Fourier’s heat model, our result suggests that the Cattaneo–Christov heat flux constitution has lower temperature and thermal boundary layer thickness. In the meantime, a high wall thickness parameter greatly upgrades the rate of heat transfer, and thermal relaxation has the opposite effect. Discussion is held regarding the effects of various miscellaneous variables on temperature, concentration, and velocity.

Utilizing the MRI findings to diagnose acute appendicitis in pregnant women

Aims: To assess the performance of magnetic resonance ımaging (MRI ) scale for the diagnosis of acute appendicitis in pregnant women and to determine the added diagnostic value of MRI imaging.
 Methods: In this retrospective study, the data of patients who presented to our hospital emergency department between January 2018 and December 2021, had clinical and laboratory findings consistent with acute appendicitis, and were diagnosed with radiological imaging, were extracted from the hospital automation system and used for statistical analysis. Ultrasound (US) was used as the first-line diagnostic method for pregnant patients, and magnetic resonance imaging (MRI) was used as the second-line diagnostic method. The success of US and MRI examinations in diagnosing acute appendicitis was evaluated. In MRI examinations, the mean values of appendix diameter and wall thickness parameters were examined, and the sensitivity, specificity, positive predictive value, and negative predictive value of periappendiceal fat tissue intensity increase, T2A lumen hyperintensity, and periappendiceal fluid parameters were evaluated. Additionally, the frequency of acute appendicitis according to trimesters was examined. SPSS v20.0 (IBM SPSS Statistics for Windows, Version 20.0; Armonk, NY, USA) package program was used for the analysis.
 Results: When the medical records of 200 patients diagnosed with appandicitis were retrospectively examined, it was determined that there were 13 pregnant cases diagnosed with MRI during this period. Sensitivity, specificity, positive predictive value, and negative predictive value were evaluated for parameters including intraluminal T2A hyperintensity, wall thickness, periappendiceal fluid accumulation, and periappendiceal fatty tissue intensity increase. İntraluminal T2A hyperintensity and also periappendiceal fatty tissue intensity increase parameter sensitivity was 100%, however the wall thickness parameter had a sensitivity of 60% and the periappendiceal fluid accumulation parameter had a sensitivity of 80%. the periappendiceal fatty tissue intensity increase parameter had a a specificity of 33.3%, which is the lowest ratio among the other parameters. there was also no significant difference in the frequency of acute appendicitis according to trimesters 
 Conclusion: MRI examination has a high success rate and can be used as the primary diagnostic method for pregnant appandicitis cases. In terms of parameter evaluation, the highest positive predictive value (90.9%) is found by the parameter of intraluminal T2 hyperintensity, and the parameter of periappendiceal fluid collection is found to be in the second place. The success of T2A lumen hyperintensity and periappendiceal fat tissue intensity increase parameters, especially in excluding negative cases, was found to be quite high.

Performance-based comparison of Xue and Yamada–Ota models of ternary hybrid nanofluid flow over a slendering stretching sheet with activation energy and melting phenomena

The practical applications of current model include materials science, heat exchangers, renewable energy, nanotechnology, manufacturing, medical treatments, and environmental engineering. Insights gained from this study could enhance material design, improve heat transfer efficiency in various systems, optimize energy conversion processes, and contribute to advancements in nanotechnology, medical therapies, and engineering design. In this investigation, melting heat transmission and non-uniform heat generation features of ternary hybrid nanofluid flow over a slender stretched sheet are examined. This proposed model goal is to compare the effectiveness of the well-known ternary hybrid nanofluid models Xue and Yamada-Ota. Utilized is a ternary hybrid nanofluid made up of titanium oxide (TiO2), aluminum oxide (Al2O3), cobalt iron oxide (CoFe2O4), and Ethylene glycol (C2H6O2) as the base fluid. The course leading equations are transformed using appropriate similarity variables, and the following equations are then mathematically solved using the shooting approach (bvp4c). The impacts of some physical parameters on the typical profiles (concentration, velocity and thermal) are explained using the Xue and Yamada-Ota models. Additionally, the same parameters are used to explore the mass and heat transfer rates, and the results are shown in tabular format. For higher values of wall thickness parameter, the velocity and thermal profiles enhance. It also reduces the rates of mass and heat transmission. The Yamada-Ota model outperforms the Xue ternary hybrid nanofluid model in terms of heat and mass transfer efficiency.

INVESTIGATION OF 3D PRINTING PARAMETERS AFFECTING THE DEVIATION OF PRODUCT BY TAGUCHI METHOD

Fused deposition modeling (FDM) printing method is widely used in the manufacture of technical parts. The article aims to present the survey results of 3D printing parameters (layer height, printing speed, wall thickness) that affect the deviation of product created by the FDM printing method. In this study, 3D scanning technology was applied to measure and check the error of each printed hole. Taguchi method is used in the experiment to design and process data in Minitab software to generate results to evaluate the input values of the investigation. The research results show that the print speed parameter has the highest influence on the error whereas the print wall thickness parameter has the lowest effect. The research results can be used to eliminate the error in making samples by the FDM method.

Partial Slip Effects for Thermally Radiative Convective Nanofluid Flow

The partial slip effects for radiative convective nanofluid flow over a stretching sheet in porous medium are analytically explored in this work. The Navier–Stokes equations, the momentum and the energy equations are converted into a set of non-linear ODEs by the similarity transformation. Using the modified optimal homotopy asymptotic method (OHAM), the resulting non-linear ODEs are analytically approximately solved. The impact of various parameters, such as: the velocity exponential factor n, the wall thickness parameter γ, the dimensionless velocity slip parameter δ1, the Prandtl number Pr, the radiation parameter R, and the dimensionless temperature jump parameter δ2, on the behaviour of the mass and heat transfer is presented. The influence of these parameters is tabular and graphically presented. An excellent agreement between the approximate analytical solution and the corresponding numerical solution is highlighted. The results obtained confirm that modified OHAM is a useful and competitive mathematical tool to explore a large class of non-linear problems with applications in various fields of science and engineering.

Numerical simulation of 3D Darcy–Forchheimer fluid flow with the energy and mass transfer over an irregular permeable surface

The Jeffrey fluid model is capable of accurately characterizing the stress relaxation behavior of non-Newtonian fluids, which a normal viscous fluid model is unable to perform. The primary objective of this paper is to provide a comprehensive investigation into the effects of MHD and thermal radiation on the 3D Jeffery fluid flow over a permeable irregular stretching surface. The consequences of the Darcy effect, variable thickness and chemical reaction are also considered. The phenomena have been modeled as a nonlinear system of PDEs. Using similarity substitution, the modeled equations are reduced to a dimensionless system of ODEs. The parametric continuation method (PCM) is used to determine the numerical solution to the obtained sets of nonlinear differential equations. The impact of physical parameters on temperature, velocity and mass profiles are presented through Figures and Tables. It has been noticed that the energy profile magnifies with the increment of porosity term, thermal radiation and heat source term, while diminishing with the flourishing upshot of power index and Deborah number. Furthermore, the porosity term and wall thickness parameter enhance the skin friction.

Numerical analysis of bioconvection-MHD flow of Williamson nanofluid with gyrotactic microbes and thermal radiation: New iterative method

Abstract The aim of this study is to investigate the numerical analysis of an innovative model containing, bioconvection phenomena with a gyrotactic motile microorganism of magnetohydrodynamics Williamson nanofluids flow along with heat and mass transfer past a stretched surface. The effect of thickness variation and thermal conductivity feature is employed in the model. Bioconvection in nanofluid helps in bioscience such as in blood flow, drug delivery, micro-enzyme, biosensors, nanomedicine, for content detection, etc. For simulation procedure, the mathematical partial differential equations are converted into dimensionless systems owing to dimensionless variations such as magnetic field, power index velocity, Williamson parameter, wall thickness parameter, thermal conductivity variation, Prandtl number, thermal radiation, Brownian motion, Lewis number, Peclet number, and different concentration parameter, etc. For numerical simulation, New Iterative Technique (NIM) numerical algorithm is adopted and employed for the linear regression planned for the proposed model. For comparison purposes, the homotopy technique is employed on the flow model. Close agreement is seen between both methods revealing the accuracy and consistency of NIM numerical technique. Many features of no-scale constraints are evaluated through graphical data for a key profile of the flow model. Results show that microorganism concentration is heavy due to the magnetic effect and Hall current.

Bidirectional rotating flow of nanofluid over a variable thickened stretching sheet with non-Fourier's heat flux and non-Fick's mass flux theory.

The flow of nanofluid over a variable thickened stretching sheet is studied in this article. Non-Fourier’s heat flux and non-Fick’s mass flux are incorporated for heat and mass flow analysis. Silver (Ag) and Copper (Cu) are considered nanoparticles with water as base fluid. The resulting equations are transformed into the dimensionless form using similarity transformation and solved by RK-4 with the shooting method. The impact of the governing parameters on the dimensionless velocity, temperature, concentration, skin friction coefficient, streamlines, and finally isotherms are incorporated. It is observed that increment in power-law index parameter uplifts the fluid flow, heat, and mass transfer. The increase in the magnitude of skin friction coefficient in (x-direction) with wall thickness parameter is high for nanofluid containing silver nanoparticles as compared to copper nanoparticles.

Bidirectional flow of MHD nanofluid with Hall current and Cattaneo-Christove heat flux toward the stretching surface.

Vacuum pump oil (VPO) is used as a lubricant in pumps of different machines. The rate of heat transport is a fundamental requirement of all phenomena. To enhance the rate of heat transmission and reduce the amount of energy consumed as a result of high temperatures. For this reason, the vacuum pump oil (VPO) is taken as a base fluid and Fe3O4 is the nanoparticles suspended in VPO. That’s why, the present study inspected the consequence of Hall current, Joule heating effect and variable thickness on these three-dimensional magnetohydrodynamics bidirectional flow of nanoliquid past on a stretchable sheet. Further, the Cattaneo-Christove heat flux and radiation impacts are also considered. The VPO−Fe3O4 nanofluid model is composed of momentum equations in x−direction, y−direction and temperature equations. The leading higher-order non-linear PDEs of the current study have been changed into non-linear ODEs with the implementation of appropriate similarity transformations. The procedure of the homotopy analysis method is hired on the resulting higher-order non-linear ODEs along with boundary conditions for the analytical solution. The significance of distinct flow parameters on the velocities in x−direction, y−direction and temperature profiles of the nanofluid have been encountered and briefly explained in a graphical form. Some important findings of the present modelling are that with the increment of nanoparticles volume fraction the nanofluid velocities in x−direction and y−direction are increased. It is also detected that higher estimations of magnetic field parameter, Prandtl number and thermal relaxation time parameter declined the nanofluid temperature. During this examination of the model, it is found that the Fe3O4-Vacuum pump oil (VPO) nanofluid enhanced the rate of heat transfer. Also, the vacuum pump oil (VPO) has many industrial and engineering applications. The current study will help to improve the rate of heat transmission by taking this into account due to which working machines will do better performance and the loss of useful energy will be decayed. Lastly, the skin friction coefficient and Nusselt number are also illustrated in a tabular form. Some major findings according to the numerical computation of the problem are that the enhancing estimations of magnetic parameter, nanoparticles volume fraction and wall thickness parameter augmented the skin friction coefficient in x−direction and Nusselt number. The reduction in skin friction coefficient of the nanofluid in y−direction is examined for Hall current and shape parameter.

Computational assessment of hybrid nanofluid flow with the influence of hall current and chemical reaction over a slender stretching surface

The current study addresses the flowof steady electrically conductinghybrid nanofluid (HNF) across an impermeable slender stretchable sheet. The flow distribution takes into consideration the effects of variablemagnetic fields, heat production, Hall current and chemical reactions. A computational model is establishedfor the purpose to amplify the energy communication rate and enhance the productivity and performanceof thermal energy propagation for several industrial and biological purposes. The hybrid nanofluid is comprised of silver and magnesium oxide nanomaterials in the working fluid water. Among transition metals and alloys, magnesium oxide and silver nanoparticles (NPs) have been extensively documented to have broad-spectrum antibacterial properties. Silver NPs are the most extensively employed inorganic NP, having several applications in biomaterial detection and antibacterial actions. The scenario has been expressed as a system of PDEs. Which are simplified to the system of ODEs through similarity replacements. The computing approach PCM is used to subsequently evaluate the acquired 1st order differential equations. The outcomesare checked with the bvp4c package and existing literature for consistency and validity. It has been noticed that the axial velocity profile enhances with the effect of Hall current m and velocity power index constraint n, while reducing with the variation of nanoparticles volume friction ϕ1,ϕ2 and slender sheet wall thickness parameter δ.

Heat and mass transfer analysis of nonlinear mixed convective hybrid nanofluid flow with multiple slip boundary conditions

The current study focuses on the 3D nonlinear mixed convective boundary layer flow of micropolar hybrid nanofluid in the presence microorganism and multiple slip conditions across the slendering surface. The concentration and energy equations are developed in the occurrence of activation energy and joule heating effect. The aim of this research is to consider the Carbon nanotubes (CNTs) which are favored materials in the manufacture of electrochemical devices because of their mechanical and chemical stability, good thermal and electrical conductivities, physiochemical consistency, and featherweight. By keeping such extraordinary properties of carbon nanotubes in mind, we investigate the flow of hybrid nanofluid having MWCNT (multi-wall carbon nanotubes) and SWCNT (single-wall carbon nanotubes). Using an appropriate similarity variable, the flow model (PDEs) are converted into nonlinear ordinary differential equations. The bvp4c approach is utilized to tackle the coupled differential equations. The impact of emerging parameter on temperature distribution, velocity field, concentration distribution, and microorganism field are presented graphically. It is noted the stronger values of wall thickness parameter and Hartmann number produces retardation effect, as a result fluid velocity declines for both SWCNT (single-wall carbon nanotubes) and MWCNT (multi-wall carbon nanotubes) hybrid nanofluid. Furthermore, the transport rate of heat and mass improves by the higher values of φ 2 for both simple and hybrid nanofluid.

Impact of non-Fourier heat flux in bidirectional flow of carbon nanotubes over a stretching sheet with variable thickness

Three-dimensional stretched flow of carbon nanotubes with variable thickness is examined. Christov proposed non-Fourier heat flux to capture impact of thermal relaxation time. Suitable transformations are used to obtain nonlinear ordinary differential systems. Convergent series solutions are derived. Influence of certain variables on the fluid properties is discussed. Findings demonstrate that the magnitude of the surface drag force is suppressed with increment in wall thickness parameter whereas it intensified for increasing nanoparticles volume fraction. Increase in the shape parameter and nanoparticles volume fraction enhanced the flow. Temperature is noticed higher with an increase in thermal relaxation time.

Flow Analysis of Hybridized Nanomaterial Liquid Flow in the Existence of Multiple Slips and Hall Current Effect over a Slendering Stretching Surface

Carbon nanotubes (CNTs) are favored materials in the manufacture of electrochemical devices because of their mechanical and chemical stability, good thermal and electrical conductivities, physiochemical consistency, and featherweight. With such intriguing carbon nanotubes properties in mind, the current research aims to investigate the flow of hybridized nano liquid containing MWCNTs (multi-wall carbon nanotubes) and SWCNTs (single-wall carbon nanotubes) across a slendering surface in the presence of a gyrotactic-microorganism. The temperature and solutal energy equation are modified with the impact of the modified Fourier and Fick’s law, binary chemical reaction, viscous dissipation, and joule heating. The slip conditions are imposed on the surface boundaries. The flow equations are converted into ODEs by applying similarity variables. The bvp4c approach is applied to tackle the coupled and extremely nonlinear boundary value problem. The outputs are compared with the PCM (Parametric continuation method) to ensure that the results are accurate. The influence of involved characteristics on energy distribution, velocity profiles, concentration, and microorganism field are presented graphically. It is noted that the stronger values of the wall thickness parameter and the Hartmann number produce a retardation effect; as a result, the fluid velocity declines for MWCNT and SWCNT hybrid nano liquid. Furthermore, the transport of the mass and heat rate improves with a higher amount of both the hybrid and simple nanofluids. The amount of local skin friction and the motile density of microorganisms are discussed and tabulated. Furthermore, the findings are validated by comparing them to the published literature, which is a notable feature of the present results. In this aspect, venerable stability has been accomplished.

Spectral computation of reactive bi-directional hydromagnetic non-Newtonian convection flow from a stretching upper parabolic surface in non-Darcyporous medium

This paper presents a mathematical model for bi-directional convection magnetohydrodynamic (MHD) tangent hyperbolic nanofluid flow from the upper horizontal subsurface of a stretching parabolic surface to a non-Darcian porous medium, as a simulation of nanocoating. Chemical reaction, activation energy and thermo solutal buoyancy effects are included. The Darcy–Brinkman–Forchheimer model is deployed which permits the analysis of inertial (second order) porous drag effects. The Buongiorno nanoscale model is deployed which includes Brownian motion and thermophoresis effects. The dimensionless, transformed, nonlinear, coupled ordinary differential equations are solved by implementing the spectral relaxation method (SRM). Validation with previous studies is included. The numerical influence of key parameters on transport characteristics is evaluated and visualized graphically. Velocity is elevated (and momentum boundary layer thickness is reduced) with increasing wall thickness parameter, permeability parameter, Forchheimer parameter, Weissenberg (rheological) parameter and modified Hartmann (magnetic body force) number. Velocity enhancement is also computed with increment in stretching rate parameter, rheological power-law index, thermal Grashof number, and species (solutal) Grashof number, and momentum boundary layer thickness diminishes. Temperature is suppressed with increasing stretching rate index and Prandtl number whereas it is substantially elevated with increasing Brownian motion and thermophoresis parameters. Velocity and temperature profiles are reduced adjacent to the parabolic surface with larger wall thickness parameter for stretching rate index [Formula: see text]1, whereas the reverse behavior is observed for stretching rate index [Formula: see text]1. Nanoparticle concentration magnitude is depleted with larger numeric of Lewis number and the Brownian motion parameter, whereas it is enhanced with greater values of the stretching index and thermophoresis parameter. The nanoparticle concentration magnitude is reduced with an increase in chemical reaction rate parameter whereas it is boosted with activation energy parameter. Skin friction, Nusselt number and Sherwood number are also computed. The study is relevant to electromagnetic nanomaterials coating processes with complex chemical reactions.

Impacts of activation energy and binary chemical reaction on MHD flow of Williamson nanofluid in Darcy–Forchheimer porous medium: a case of expanding sheet of variable thickness

An expanding sheet problem is more relevant when the thickness of the sheet is variable and it bears frequent applications in polymer press, paper production, metallic plate cooling, etc. On the other hand, activation energy is an important phenomenon of chemical reaction in flow dynamics of Newtonian and non-Newtonian fluids. The activation energy and chemical reaction have vital applications in food preparing, the mechanism of water and oil emulsions, chemical engineering, and more. So in this project, the impacts of activation energy and binary chemical reaction on MHD two-dimensional boundary layer flow of Williamson nanofluid on an expanding surface of variable thickness embedded in Darcy–Forchheimer porous medium are investigated. Using suitable transformations, the governing equations are transformed into a set of non-linear ordinary differential equations (ODEs). Later, numerical solutions have been achieved by well-known MATLAB inbuilt function ‘bvp4c’. Several vital results are explored for variations of involved physical parameters and those are presented in graphical and tabular modes. The achieved results suggest that when wall thickness parameter increases, there is a contrast in behaviors of velocity, temperature and nanoparticle concentration if there is a condition that the shape parameter is greater than or less than unity. For the former case, the above flow properties reduce with wall thickness parameter, whereas, for the latter case, those are showing significant growth. The Brownian motion of nanoparticles causes an increase in temperature and a reduction in nanoparticle concentration, whereas due to thermophoretic force, both temperature and nanoparticle concentration rise. Due to the presence of activation energy in chemical reaction, the nanoparticle concentration enhances, while, temperature decreases(increases) near(away from) the sheet. With increasing reaction rate parameters, nanoparticle concentration diminishes, but temperature increases near the sheet. The surface drag force decreases with Williamson fluid parameter, while it increases with the magnetic parameter, inverse Darcy number, and Forchheimer parameter. On the other hand, the surface heat flux and surface mass flux are decreasing functions of Williamson fluid parameter, magnetic parameter, inverse Darcy number, and Forchheimer parameter. It also reveals that surface heat flux reduces with increasing reaction rate parameters, whereas surface mass flux increases. Finally, for the growth of activation energy parameter, initially surface heat flux rises and surface mass flux declines, but for its larger values, the quantities turn out to be constants. Also, the surface heat and mass fluxes are decreasing functions of thermophoresis parameter.

MHD Williamson Nanofluid Flow over a Slender Elastic Sheet of Irregular Thickness in the Presence of Bioconvection.

Bioconvection phenomena for MHD Williamson nanofluid flow over an extending sheet of irregular thickness are investigated theoretically, and non-uniform viscosity and thermal conductivity depending on temperature are taken into account. The magnetic field of uniform strength creates a magnetohydrodynamics effect. The basic formulation of the model developed in partial differential equations which are later transmuted into ordinary differential equations by employing similarity variables. To elucidate the influences of controlling parameters on dependent quantities of physical significance, a computational procedure based on the Runge–Kutta method along shooting technique is coded in MATLAB platform. This is a widely used procedure for the solution of such problems because it is efficient with fifth-order accuracy and cost-effectiveness. The enumeration of the results reveals that Williamson fluid parameter , variable viscosity parameter and wall thickness parameter impart reciprocally decreasing effect on fluid velocity whereas these parameters directly enhance the fluid temperature. The fluid temperature is also improved with Brownian motion parameter and thermophoresis parameter . The boosted value of Brownian motion and Lewis number reduce the concentration of nanoparticles. The higher inputs of Peclet number and bioconvection Lewis number decline the bioconvection distribution. The velocity of non-Newtonian (Williamson nanofluid) is less than the viscous nanofluid but temperature behaves oppositely.

Impact of Soret and Dufour on MHD mixed convective flow of non‐Newtonian fluid over a coagulated surface

AbstractIn the present study, we investigated the steady, two‐dimensional mixed convective stagnation point flow of an electrically conducting micropolar fluid due to stretching of a variable thicked surface in the attendance of viscous dissipation. The flow is incompressible and laminar. The combined heat and mass transfer features are investigated. Convective and diffusion conditions are considered. The nonlinear thermal radiation, thermo‐diffusion, and diffusion thermal effects are considered. The governing partial differential equations are converted to ordinary differential equations by using the appropriate similarity transformations. The obtained nonlinear and coupled ordinary differential equations are elucidated numerically using the fourth‐order Runge–Kutta based shooting technique. The influence of various nondimensional parameters on the flow field like velocity, microrotation, temperature, and concentration is examined with the assistance of graphs. Results indicate that the Dufour number has a proclivity to increase the distributions of concentration and temperature correspondingly. Also, fluid temperature and concentration enhance for increasing values of the wall thickness parameter.

Robotic-based terahertz imaging for nondestructive testing of a PVC pipe cap

The detection and localization of damage in a polyvinyl chloride (PVC) pipe cap were experimentally investigated by performing pulsed terahertz time-domain spectroscopy and using a six-degree-of-freedom (DOF) robotic arm. This study focuses on the development of a 3D imaging system to monitor the thickness of and detect defects in 3D structures. The damage and thickness of the PVC pipe cap were monitored by designing the reflection geometry of the terahertz scanner based on optical components, such as beam splitter and focal lens. Additionally, the PVC pipe cap was controlled with a six-DOF robot arm for path planning. The corresponding predicted value for the thickness of the sample was computed as a function of at least one wall thickness parameter of the pipe that uses a captured terahertz wave because these waves are partially reflected when the medium is changed. The defects were simulated using a PVC pipe cap (inner diameter: 89 mm, outer diameter: 100 mm), and the specimen was mounted on a six-DOF robot arm to inspect the entire area of the PVC pipe cap. The reflected signals were analyzed to determine the thickness, defectiveness, and locations of the defects through signal processing in the time and frequency domains. Consequently, we can detect and visualize the various types of defects that are simulated in a PVC pipe cap. In addition, the validity of the structural health monitoring method for 3D structures using terahertz waves was successfully verified.