Velocity Profiles Research Articles

Viscosities of inhomogeneous systems from generalized entropy scaling

This study extends entropy scaling to inhomogeneous fluids by using the classical density functional theory together with a new viscosity reference that takes into account the influence of solid–fluid interactions on the fluid viscosity. The density functional theory uses a Helmholtz energy functional based on the perturbed-chain statistical associating fluid theory; the local residual entropy per particle is determined from the temperature derivative of the Helmholtz energy functional in combination with an appropriate weighted density profile. The weighted density calculation requires a single transferable parameter, which is adjusted to a reference molecular dynamics simulation. In particular, local viscosity values for fluids under nanoconfinement near solid–fluid interfaces are predicted using the same entropy scaling parameters as for homogeneous fluids. We validate the model by comparing viscosity and velocity profiles with results from non-equilibrium molecular dynamics simulations of a Couette flow in a slit pore. Good agreement is found between the entropy scaling model and the non-equilibrium molecular dynamics results for both the viscosity and velocity profiles of the Lennard–Jones truncated and shifted fluid. The proposed model extrapolates well to systems with different temperatures, fluid densities, and shear forces as well as to systems with different wetting behaviors. These results demonstrate that entropy scaling can be generalized to inhomogeneous fluids using an appropriate combination of residual entropy profile and viscosity reference.

Influence of inflow conditions on simplified heavy vehicle wake

In the current study, the impact of various inflow conditions, including turbulent wind profiles and turbulent intensity, on the wake flow topology of a simplified ground transportation system (GTS) model was investigated using the improved delayed detached eddy simulation. The reliability and accuracy of the numerical method adopted in this paper were verified against the results comprising the aerodynamic drag and the wake flow structure of the GTS model obtained from the large eddy simulation and the experimental data. The research results indicate that turbulent winds characterized by logarithmic and uniform velocity profiles resulted in significantly different wake flow topologies yet exhibit the same dominant frequency. The turbulent intensity also plays a crucial role in the wake of the GTS model. It is observed that an increase in turbulence intensity corresponds with a rise in the aerodynamic drag. Specifically, when the turbulence intensity is set at 15%, there is a 3.68% increase in the aerodynamic drag of the GTS model compared to a case where the turbulence intensity was only 5%. In addition, the turbulent intensity is critical to the dominant frequency characteristics of the wake region of the GTS model. These results demonstrate that both the velocity profiles and the turbulence intensities significantly influence the wake flow topology and aerodynamic drag of the GTS model, providing a valuable reference for establishing appropriate inflow conditions and exploring the formation mechanism of flow topology in the wake of the GTS model.

Magnetized heat transfer visualization through computational modeling of third-grade fluid via exponentially stretching cylinder

The steady MHD boundary-layer axis-symmetric flow of a third-grade fluid passing through an exponentially expanded cylinder in the vicinity of a magnetic field is investigated in this study. The problem is mathematically modeled. Suitable similarity transformations are carried out to convert the partial differential equations into nonlinear ordinary differential equations. The Runge–Kutta fourth-order shooting technique is used to solve the transmuted system of nonlinear ODEs. Graphical representations of numerical findings are used to examine the effects of various physical factors on the velocity and temperature profiles. The influence of fluid variables on the velocity curve, such as third-grade parameters, second-grade parameters, and Reynolds number, is illustrated and explored. The skin-friction coefficient expression is computed and given. The widths of the velocity and momentum boundary layers are revealed to be increasing functions of the curvature parameter. It is found that the third-grade fluid has a higher velocity profile than Newtonian and second-grade fluids. Also, the stretched cylinders cause a more progressive shift in heat and mass pattern for flow than flat plates do.

On the shear-induced lift in two-way coupled turbulent channel flow laden with heavy particles

The importance of shear-induced lift, i.e. Saffman lift, is investigated in two-way coupling point-particle direct numerical simulation of turbulent channel flow laden with heavy particles. A new criterion is established for the critical particle diameter normalized by wall viscous length, and the effect of Saffman lift on particle motion can be neglected when the particle diameter is smaller than the critical value. The new criterion agrees well with the numerical results. We further study the influence of Saffman lift on particle motion and turbulence modulation. The results suggest that the Saffman lift will increase near-wall particle velocity and reduce particle accumulation therein. By integrating the particle motion equation, it is demonstrated that the mean particle streamwise velocity is dependent on the particle wall-normal velocity. This theoretically explains why the presence of a wall-normal force alters the streamwise velocity of particles. A theoretical profile of mean particle streamwise velocity at different Stokes numbers is then obtained by introducing the diffusive gradient hypothesis and Prandtl mixing length model. In addition, the present results reveal that the Saffman lift tends to augment the level of turbulence attenuation. The spectral analysis shows that the Saffman lift reduces the turbulent energy of small scales in the buffer region and large structures in the logarithmic region. When the Saffman lift is absent, near-wall particle streaks can be observed in the buffer region, which tend to separate fluid streaks. By contrast, the Saffman lift tends to prevent the formation of near-wall particle streaks.

Numerical comparison of nonlinear thermal radiation and chemically reactive bio-convection flow of Casson-Carreau nano-liquid with gyro-tactic microorganisms: Lie group theoretic approach

The current research presents a mathematical model to study the flow of a non-Newtonian magnetohydrodynamics (MHD) Casson-Carreau nanofluid (CCNF) over a stretching porous surface, considering mass and heat transport rates with Stefan blowing, non-linear thermal radiation, heat source-sink, chemical reaction, thermophoretic and Brownian motions, convective heating, Joule heating, motile microorganisms, and bio-convection. The presence of microorganisms is utilized to control the suspension of nanomaterials within the nanofluid. The current flow model has been rendered by the boundary layer approximation and we get the highly nonlinear partial differential equations (PDEs). These nonlinear PDEs are simplified by the novel Lie group theoretic method. The one-parameter Lie scaling method simplified the PDEs and convert it into the ordinary differential equations (ODEs). Numerical solutions for these ODEs are obtained using the bvp4c scheme built-in function in MATLAB, ensuring reliable outcomes for temperature, velocity, concentration, and motile microorganism density profiles. The numerical results are presented through graphs and compared with available data, showing good agreement. These numerical outcomes reveal several important flow characteristics. Rates of change for Nr are 0.0007 and 0.0005, and for Ω, they are −0.0754 and −0.0536, respectively. Similarly, the rate of change for Rb in both models is −0.002 and −0.0002. Analysis shows a positive impact of the bioconvection Rayleigh number in both models, notably higher for the Casson fluid compared to the Carreau fluid model. Buoyancy ratio parameter exhibits consistent rates of change, while the reduction in impact is more pronounced for the Casson fluid model in the case of the mixed bioconvection parameter. The mixed bio-convection parameter reduces momentum velocity for both Casson and Carreau fluids, whereas the Darcy parameter boosts fluid velocity. As the Newtonian heating parameter increases, the temperature velocity distribution of both fluids also increases. The concentration profile of both Casson-Carreau fluid phases declines as the heat source-sink parameter and Schmidt number increase. Microbial velocity shows a decrease with increasing R values, whereas the opposite trend is observed for the Peclet number Pe.

Comparison of Near-Surface Attenuation from Surface Array-Based Seismic Noise Data and Borehole Weak-Motion Recordings at the STIN Test Site in Northeastern Italy

Abstract Seismic wave attenuation and the related shear-wave quality factor (QS) in the near surface are crucial parameters for ground motion simulations and seismic hazard assessments. Although recent approaches developed to calculate QS from seismic noise acquired by surface arrays have been accepted for practice, additional testing and comparison of results estimated using various geophysical methods are still necessary to verify the reliability of such techniques. This work presents the results of an experiment conducted at the STIN site in northeastern Italy, which is equipped with a 100 m deep instrumented borehole. A seismic noise campaign was implemented by installing a temporary independent local surface array of seismological stations. The gathered data were used to initially estimate the shear-wave velocity (VS) profile and frequency-dependent Rayleigh-wave attenuation, and subsequently determine the QS factor via a linearized inversion method. The study compares these findings with the VS and QS values derived from analyzing weak-motion events recorded by two permanent seismic sensors positioned at the top and bottom of the well. The results confirm the potential of the inversion procedure used to obtain QS from local-scale seismic noise arrays as a promising approach for conducting attenuation studies at the local level in less geologically complex sites.

Thermally Driven Winds on Mars: A Review and a Slope Effect Numerical Study

AbstractRegional and local thermally driven winds are planetary boundary layer phenomena frequently observed on Mars over sloping and flat regions, when diurnal surface temperature variations are significant and large‐scale winds are sufficiently weak. In particular, slope flows are prevalent in many areas on Mars, where they can reach high speeds and have a substantial impact on the near‐surface wind patterns, pressure diurnal cycle, aeolian activity, etc. This work first reviews literature on Martian winds, listing wind speeds obtained either numerically or from in situ measurements, with special emphasis on slope flows. Second, a methodology is presented to perform numerical simulations of slope flows on Mars using the open‐source computational fluid dynamics code OpenFOAM. Slope winds are then studied in a simplified Martian mountain‐valley configuration, using realistic values for various parameters, such as the slope angle and temperature variation. The incompressible Navier‐Stokes equations with Boussinesq approximation are used, along with the k‐ɛ Reynolds‐averaged Navier‐Stokes turbulence model. Radiant heat transfer is included and proven to be paramount for a correct description of Martian slope winds. Results of velocity and temperature profiles are obtained for various slope angles. These simulations aim to provide further insight on the behavior of slope winds on Mars, to simplify the process of assessing numerous potential landing sites for upcoming missions, since these highly regular winds could be useful, for instance, for dust removal applications.

Investigation of Generalized Fourier and Fick’s Law of Electro-Osmotic MHD Two-Phase Flow of Dusty Hybrid Ferrofluid Through Inclined Microchannel

Numerous industries, including biology and medicine, stand to benefit greatly from the cutting-edge use of electro-osmotic MHD flow of hybrid Ferro fluid via a microchannel. To investigate the electroosmotic MHD flow of a hybrid Ferro fluid with dust particles, we use a microchannel inclined vertically. We also take into account the magnetic field’s transverse component. The impacts of heat and mass transfer within this fluid system are the focus of this investigation. Partial differential equations are a powerful tool for modeling the aforementioned physical phenomena. The classical system is further fractionalized into a nondimensional form by using suitable nondimensional variables, free of dimensions, the generalized Fourier transform, and Fick’s rule. The Caputo derivative is used as a starting point for generalizations. The analytical solutions for the velocity (containing the hybrid Ferro fluid and dusty fluid), temperature, and concentration profiles are obtained using a mixture of Laplace and Fourier methods. The research looks at how things like temperature, stress (Grashof, Schmidt, and Prandtl numbers), and the dusty fluid parameter affect one another. The concentration distributions are analyzed, and graphs are presented to help visualize the results. The average values for the Sherwood number, the heat transfer rate, and the coefficient of skin friction are provided. Notably, the fractional models provide more leeway in finding workable solutions since they are more precise. All things considered, it seems that these strategies are quite beneficial. The hybrid Ferro fluid has the capacity to effectively modify the velocity boundary layer and has a greater heat transfer rate than both nanofluid and conventional fluid.

Thermal dynamics assessment for multi-phase flow analysis with motile cilia and electric double layer effects: Application of Levenberg–Marquardt backpropagation NNs

Ciliary movement holds substantial importance in the realm of biomedical research. Disorders arising from impaired ciliary motion, such as primary ciliary dyskinesia and specific respiratory ailments, underscore the critical need to investigate both the normal functioning and dysfunction of cilia. Such research is fundamental to the development of effective treatments and therapies. This work explores the application of Levenberg–Marquardt backpropagation neural networks (LMBP-NNs) for simulating the flow of a non-Newtonian Jeffery fluid in peristaltic motion. Inspired by synchronous ciliary movement, microfluidic systems mimicking cilia functionality have been developed. These artificial cilia can generate controlled fluid flow patterns, enabling various applications such as drug delivery, mixing, and particle sorting in lab-on-a-chip devices. The present study focuses on measuring thermal and mass transfer in beating cilia during multiphase peristaltic pumping of Jeffery fluid in two- and three-dimensional channels using transverse magnetohydrodynamics in a porous medium. The governing equations for the non-Newtonian Jeffery fluid in both the fluid and dusty phases are formulated, and exact solutions are calculated for fluid phase velocity, particulate phase velocity, temperature, concentration, and pressure gradient. The physical behavior is investigated by graphing dimensionless parameters for velocity, temperature, and concentration profiles in both solid and liquid phases. The trapping phenomena is depicted by showing streamlines of various dimensionless characteristics such as porosity velocity and volume percentage. The LMBP-NNs approach is then used to train, test, and verify the neural network models using the reference datasets. The accuracy of the LMBP-NN is assessed using statistical data such as mean square error, curve fitting graphs, regression plots, and error histograms. The study also investigates flow model limits for momentum, temperature, and concentration profiles using visual representations. This study illustrates the computational capability of LMBP-NNs in modeling the peristaltic flow of Jeffery fluid and gives useful insights into fluid flow behavior in microfluidic devices containing artificial cilia. The findings help to better understand and optimize these systems for a variety of fluid manipulation and transportation applications.

Magnetohydrodynamic flow of carbon nanotubes and heat transfer over a moving thin Needle: A numerical and research surface methodology

A steady flow of carbon nanotubes (CNTs) nanofluids and heat transfer past a horizontally moving thin needle are investigated under the influence of magnetohydrodynamic (MHD). Single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) are the two main nanoparticles that represent CNTs. The slender needle moves relative to the flow with parallel velocity in either the same or opposite direction. Using the similarity method, a system of partial differential equations (PDEs) subject to boundary conditions is converted into nondimensional ordinary equations (ODEs). The ODEs are then reduced to a first-order ODEs system and solved using the MATLAB R2022b bvp4c solver. On a numerical scale, the impacts of varying potential parameters, such as the magnetic, CNTs’ volume fraction, and moving parameters, on the velocity and temperature profiles, the skin friction, and heat transfer coefficients are investigated. Utilising response surface methodology (RSM), the optimisation of the response based on numerical experimentation of physical quantities is performed. The outcomes are depicted using tables and a graphical approach. Results indicate the existence of dual solutions when the needle travels in the opposite direction. Moreover, the increase in the magnetic parameter by 100% in the flow will increase both the skin friction and heat transfer coefficients by nearly 30% and 4%, respectively. Furthermore, when the value of the CNTs volume fraction increases by 100%, the heat transfer rate increases substantially by almost 33%.However, doubling the size of the thin needle cansignificantly reduce the skin friction coefficient by nearly 32%. RSM results demonstrate that the maximal heat transfer coefficient is generated at the highest values of the magnetic and CNTs’ volume friction parameters and the lowest value of the needle size parameter. Findings also show that SWCTNs are superior to MWCNTs both in the skin friction and heat transfer coefficients. When comparing the performance of water and kerosene, we find that water is less effective as a base fluid than kerosene.

Heat and Mass Transfer in Unsteady Radiating MHD Flow of a Maxwell Fluid with a Porous Vertically Stretching Sheet in the Presence of Activation Energy and Thermal Diffusion Effects

The aim of this study is to analyze the effects of activation energy and thermal diffusion an unsteady MHD reactive Maxwell fluid flow past a porous stretching sheet in the presence of Brownian motion, Thermophoresis and nonlinear thermal. The non-linear partial differential equations that govern the fluid flow have been transformed into a two-point boundary value problem using similarity variables and then solved numerically by fourth order Runge–Kutta method with shooting technique. Graphical results are discussed for non-dimensional velocity, temperature and concentration profiles while numerical values of the skin friction, Nusselt number and Sherwood number are presented in tabular form for various values of parameters controlling the flow system. The present study is compared with the previous literature and found to be in good agreement.

Disturbance Observer-Based Tracking Control of High-Speed Trains Under Adhesion Dynamics

As the anti-skid control and speed tracking control of high-speed trains (HSTs) are interrelated and mutually constrained, it is very challenging to achieve simultaneous tracking of speed and slip ratio. In this paper, it is proposed for the first time that when the traction braking force has been limited to a reasonable range by the adhesion anti-skid condition, the high-precision tracking of the position and velocity curves of HSTs can be achieved, and the tracking error of the slip ratio is acceptable. Firstly, a novel modelling of the adhesion dynamics of HSTs under realistic gusts of wind disturbance is developed, and a model based on strict feedback is obtained by linearising the feedback for high-order non-linear systems. Then, this paper first presents the design scheme of fast terminal sliding mode controller based on disturbance observer for HSTs, which can ensure the anti-disturbance performance and accurate tracking of HSTs. Finally, an example is used to verify the validity of the results. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —The actual traction/braking force of HSTs is provided by adhesion, and the existing literature on slip ratio tracking essentially sacrifices the tracking performance of the traction/braking system to meet the anti-skid requirements, while considering velocity and position tracking alone may leave the train in an undesired condition such as “idling” or “skidding”. This paper seeks to achieve high accuracy tracking of velocity and position profiles of HSTs under restricting the slip ratio to a reasonable range, which is expected to be an effective method for train tracking controller design. To avoid discomfort to passengers, nonlinearities dynamics are considered and an anti-disturbance controller is designed to compensate the impact of natural wind disturbances. To enhance the practicality, feedback linearization is introduced to reduce the complexity of the controller implementation. The designed fast terminal sliding mode controller also avoids jitter and singularity problems and obtains finite time stability. The stability analysis and numerical simulation have confirmed the effectiveness of the proposed scheme, which still needs to be verified by experiments in the future.

Numerical Investigation of Diffusion Thermo and Thermal Diffusion on MHD Convective Flow of Williamson Nanofluid on a Stretching Surface Through a Porous Medium in the Presence Chemical Reaction and Thermal Radiation

In this paper, analyze the impact of Diffusion thermo and thermal diffusion with heat and mass transfer inherent of thermally radiant Williamson nanofluid over a stretyching surface through a porous medium under the convective boundary condition in the presence of thermal radiation and chemical reaction has been studied. The coefficients of Brownian and thermophoresis diffusions are also taken into consideration. The governing partial differential equations are reduced to a couple of nonlinear ordinary differential equations by using suitable transformation equations; these equations are then solved numerically with the use of the conventional fourth-order Runge Kutta method accompanied by the shooting technique. As a result, the effects of various physical parameters on the velocity, temperature, and nanoparticle concentration profiles as well as on the skin friction coefficient and rate of heat transfer are discussed with the aid of graphs and tables. This study has been directly applied in the pharmaceutical industry, microfluidic technology, microbial improved oil recovery, modelling oil and gas-bearing sedimentary basins, and many other fields. Further, to check the accuracy and validation of the present results, satisfactory concurrence is observed with the existing literature.

Thermal and solutal transport by Cattaneo-Christov model for the magnetohydrodynamic Williamson fluid with joule heating and heat source/sink

This article scrutinizes the 2-dimensional and boundary layer flow of magnetohydrodynamic Williamson fluid flowing on a stretchable surface with variable viscosity. The thermal and solutal rates are examined through the Cattaneo-Christov model with Joule heating, heat source/sink, and chemical reaction. The authors are motivated to conduct this study because of its practical and scientific significance in various processes, including polymer processing, textile industries, food industries, solar energy, biomedical science, wind turbine blades, oil spill clean-up, metal rolling, and forging. With the mentioned assumptions, the partial differential equations are achieved by using the basic governing laws, including momentum law, energy law, and concentration law. This non-linear system of equations is transmuted into ordinary differential equations by taking similarity transformations. The main novelty behind the conduction of this work is the numerical technique, namely the ‘Adams-Milne (Predictor-Corrector)’ method along with the Runge-Kutta technique on Matlab software, which has not previously been studied by any researcher in the literature. The analytical solution of the determined equations is not possible due to their highly non-linear nature; therefore the multistep numerical method namely the ‘Adams-Milne (Predictor-Corrector)’ method, along with the Runge-Kutta technique is used to determine the numerical results. The outcomes are noted due to numerous parameters for velocity, temperature, and concentration profiles. The explanation of graphical and numerical results is discussed here. The graphical impression of the Williamson parameter reveals that the velocity and temperature curves diminish for higher inputs of this parameter. The movement of fluid shows the declining behavior for the Hartmann number and viscosity parameter. The solutal and thermal findings due to Cattaneo-Christov heat and mass relaxation coefficients mark the reducing behaviour in respective field. The rise in reaction coefficient decreases the mass distribution. The analyses of comparison of results are also presented here.

Study on the film thickness and surface wave velocity of the thin liquid film formed by a round jet obliquely impinging on a horizontal plate

For a thin liquid film (in a supercritical flow) prior to the formation of a non-circular hydraulic jump formed by a round jet obliquely impinging on a horizontal plate, the time-averaged film thickness and the surface wave velocity are extracted based on the measured transient film thickness. On the one hand, the effect of many factors, including the jet velocity, impingement angle, azimuthal angle, liquid viscosity, and surface tension, on the time-averaged film thickness and surface wave velocity are discussed. When the jet Reynolds number increases to about 1.4×104, the film thickness profile suddenly increases, and the transition of liquid flow from laminar to turbulent occurs. Meanwhile, a rapid increase is observed downstream of the turbulent film thickness profile. The influence of surface tension on the time-averaged film thickness and surface wave velocity is negligible for thin liquid films before non-circular hydraulic jumps. Nonetheless, the surface tension has a significant influence on the interface profile of non-circular hydraulic jumps. Furthermore, a “crescent” kink region upstream of the jump can be identified when the surface tension is lower than 40.6 mN/m. On the other hand, experimental results are used to verify the prediction accuracy of existing approximate solutions. The laminar approximate solution with a quadratic boundary layer velocity profile can accurately predict the film thickness distribution of most laminar thin liquid films, except downstream of the thin liquid films with a dynamic viscosity higher than 9.71 mPa s. The surface wave velocities are found to be close to the predicted surface velocities of the approximate solutions.

Site effect evaluation for Culiacan, Sinaloa, Mexico

Using the spectral ratio technique (HVSR), we performed an analysis of 120 seismic noise records obtained at different points distributed throughout the city of Culiacán, Sinaloa, México. The results show a clear relationship of dominant periods between 0.2 to 0.7 for the alluvium zone in the central and western area of the city and minor periods for points near outcrops of igneous rocks south and southeast of the city. The higher relative amplitudes were found along the riverbed, in the transition zone of conglomerate deposits to alluvium. We performed a multichannel analysis (station arrays) at some points in which we also measured H/V. Afterward, we produced velocity profiles were obtained and transfer functions were calculated. Five of these values were compared with the HVSR technique. Three of them could be compared with the surficial startigraphy obtained in soil mechanics studies to which access was granted.

Liquid flow field and residence time distribution in a baffleless oscillatory flow coil reactor

Baffleless coils can operate as continuous oscillatory flow reactors to produce pharmaceutical products where process intensification is intended. A method to evaluate mixing performance and its impact on reaction conversion is residence time distribution (RTD) analysis. Liquid macromixing in a long baffleless coil reactor (L = 24 m, dt = 4.57 mm) at ranges of oscillation amplitude (11.75–58.75 mm), frequency (0–3.68 Hz), and net flow rate (30–120 g∙min−1) was investigated based on measured RTDs fitted to the skewed normal distribution model. The impact of operating conditions on the RTD was supported by analyzing the liquid flow field derived from CFD simulations. The RTD variance under different oscillation conditions suggests a near plug flow pattern, although deviations from ideality such as skewness and long tailing were always observed. The model parameters, along with the RTD variance, were correlated to the operating conditions lumped in an oscillatory Dean number that used the flow amplitude as characteristic length (Deox). Values of Deox varied between 150 and 11000, and the RTD variance at the different net flow rates was minimized for 300 < Deox < 600, as also evidenced from the minimum cross-sectional variance of the simulated time-averaged axial velocity profile. Normalizing the data allowed comparison to similar coil studies with different geometrical dimensions and operating conditions, leading to generalized correlations for the RTD model parameters. Finally, chemical conversion was assessed for first- and second-order single phase reactions at different Damköhler numbers using the segregation and maximum mixedness micromixing models combined with the fitted RTDs. The performance of the coil remained consistent with a plug flow reactor despite its departures from ideal flow.

Insights Into Viscosity/Thermal Conductivity of a Micropolar Nanofluid Flow Near a Horizontal Cylinder

The purpose of this study is examining the changes in viscosity and thermal conductivity of a micropolar nanofluid on a horizontal cylinder, specifically on the axisymmetric stagnation inflow. Nanofluid viscosity is known to exhibit an exponential change with temperature, while thermal conductivity was found as a linear with temperature to enhance the heat transfer rates of nanofluid flow by numerical calculations. A horizontal circular cylinder with an axisymmetric stationary point was the subject of the mathematical model, which described an incompressible, constant micropolar nanofluid flow over it. The importance of predicting heat and mass transfer for a horizontal cylinder are common in many applications, including refrigerator condensers and flat-plate solar collectors. For this reason, it is imperative to study heat and mass transfer in horizontal cylinder geometries. Furthermore, taken into account were fluid temperature factors like nanofluid viscosity and micro-rotation viscosity. It introduced aluminum oxide nanoparticles to two common fluids: pure water and ethylene glycol. It was capable of to estimate the pressure gradient profiles, temperature gradient profiles, shear stress, Nusselt number, angular and azimuthal velocities, and curvature parameters for various numerical values of micropolar, variable viscosity/thermal conductivity, and curvature. An exact match is found in a table that contrasts the current numerical computation with the published data. Based on our simulation results, it seems that the temperature profile variation for both pure water with alumina nanoparticles and ethylene glycol is significantly influenced by the Reynolds number and the viscosity/thermal conductivity characteristics of the nanofluid. Nevertheless, the micropolar parameter barely makes a difference. Furthermore, the concavity of the pressure profiles is pushed upwards, and it appears that the pressure biographies for ethylene glycol are more pressure-intensive than those for pure water. By increasing the value of the variable viscosity parameter of the nanofluids, it can be achieved to discern clearly between the angular velocity profiles in the two scenarios. Engineers and researchers working on propulsion technology for missiles, airplanes, and spacecraft can especially benefit from these perceptions.

(216) - HeartMate 3 LVAD Outflow Graft Velocity Profile as Simplified Marker for Left Ventricular Unloading in Echocardiographic Speed Ramp Tests

(216) - HeartMate 3 LVAD Outflow Graft Velocity Profile as Simplified Marker for Left Ventricular Unloading in Echocardiographic Speed Ramp Tests

Rozwiązanie problemu tworzenia się zatorów w rurociągach podczas transportu gazu poprzez proces automatycznego strumieniowania

The article presents the application of autoejection process to ensure efficient operation of pipeline systems and gas separation installations when it is impossible to remove and utilize the condensate from the pipelines. Thus, in the suggested ejector, a single common stream is separated into two streams, i.e., an active and a passive stream, as opposed to two separate independent streams in existing ejection devices. As a result, we refer to such an ejection process as autoejection, or a self-ejection process. Such a procedure is run in the pipeline with the goal of blowing and dusting the liquid phase through the central high-velocity nozzle in circumstances of mass blocking and coating rather than expelling the liquid from the pipes. On the cross-sectional area of the belts, the velocity profiles of flows in laminar and turbulent regimes are known to differ greatly from one another. The adhesion forces acting from the tube's central axis outwards, towards its walls cause the flow rate to decrease. There is a cross-sectional interaction of flows in this mode, according to experimental studies of turbulent flows. As a result, compared to the laminar domain, the flow velocities in this regime are more equally distributed across the cross-section of the flow, and their values are roughly equal to the flow's average value. In this case, based on the dependences of the flow ∆p = f(W), it is known from the calculations and the table that at such velocity limits of the flows, the “braking” pressure (p0) of the liquid coating on the pipe walls corresponds to the maximum velocity of the central gas flow. The autoejection process can occur due to the difference between the static pressures. Unsaturated absorbent coatings can be blasted off the tube absorber's walls using this technique and blended back into the main gas stream. Gas-liquid autoejectors installed along the pipe absorber's length make it possible to use this method. The purpose and principles of autoejectors’ operation are considered and a perspective of their application in tube absorbers is noted.