Velocity Profiles Research Articles

Eco-driving control for connected plug-in hybrid electric vehicles in urban scenarios with enhanced lane change engagement

Eco-driving control techniques have shown significant potential in reducing energy consumption in urban scenarios. The presence of slow-moving vehicles typically disrupts ecological velocity planning, leading to an increase in energy consumption. To solve it, this study proposes a hierarchical eco-driving control strategy, that integrates speed optimization and lane change decision-making in urban scenarios, to not only ensure traffic efficiency, but also save the energy consumption. Firstly, a data-driven energy model is leveraged in the upper level to estimate the energy consumption of candidate lanes and generate ecological lane change decisions. Then, in the lower level, the preceding vehicles and traffic lights are considered to plan an ecological velocity profile via deep reinforcement learning algorithm after transitions to the target driving lane, thereby enhancing the fuel economy and travel efficiency. A virtual driving environment model is established to verify the proposed method through numerous simulation cases. The results indicate that the proposed method effectively reduces energy consumption while maintaining favorable travel efficiency, compared with conventional benchmarks. Furthermore, the notable improvements are observed particularly in free traffic conditions.

Connecting the Low to High Corona: Propagating Disturbances as Tracers of the Near-Sun Solar Wind

We revisit a quiet 14 day period of solar minimum during 2008 January and track substreamer propagating disturbances (PDs) from low heights in STEREO/EUVI to the extended corona through STEREO/COR1 and into STEREO/COR2 along nonradial paths that trace the structure of the underlying streamers. Using our recently developed method for generating nonradial height–time profiles of outward PDs (OPDs) and inward PDs (IPDs), we obtained their velocities along the radial and position angle directions. Our analysis of 417 unique OPDs revealed two classes: slow and fast OPDs. Slow OPDs form preferentially at ≈1.6 R ⊙ closer to the streamer boundaries, with asymmetric occurrence rates, and show speeds of 16.4−8.4+26.6kms−1 at 1.5 R ⊙ and accelerate up to 200.1−57.9+71.1kms−1 at 7.5 R ⊙. Fast OPDs form preferentially at ≈1.6 R ⊙ and at ≈3.0 R ⊙ both at the streamer boundaries and slightly more often within them. They show speeds of 87.8−24.8+59.1kms−1 at 1.5 R ⊙ up to 197.8−46.7+61.8kms−1 at 7.5 R ⊙. IPDs are observed forming at ≈1.8 R ⊙ with speeds of tens of kilometers per second, mostly concentrated in the aftermath of a coronal mass ejection eruption. We present an example in which we show that periodic brightness variations related to OPDs remained in the range of 98 to 128 minutes, down to ≈2.0 R ⊙, well within the field of view of COR1. The velocity profiles of slow OPDs for a heliocentric height below 3.0 R ⊙ show good agreement with speeds more closely related to the bulk solar wind obtained via interplanetary scintillation.

Numerical Simulation and Neural Network Model for Hydromagnetic Nanofluid Convection in a Porous Wavy Channel with Thermal Non-Equilibrium Model

Abstract The present study aims to analyze the nonfluid MHD convective heat transfer in a porous wavy channel with a local thermal non-equilibrium (LTNE) model. Such a model finds applications related to enhancement in thermal performance, increasing the heat transfer coefficient in the compact design of heat exchangers for the aerospace and automotive industries and elevation in the efficiency of the solar collector. A sinusoidal porous wavy LTNE channel containing nanofluid and subjected to the induced and applied magnetic fields is considered. A uniform magnetic field is applied orthogonal to the channel and the induced magnetic field effects are considered due to the large magnetic Reynolds number. The momentum, continuity, energy, and nanoparticle volume fraction equations constitute the coupled nonlinear system of differential equations and are solved using the Galerkin finite element method. The reliability of the technique is assessed by comparing the proposed procedure with the results from earlier sources. A detailed analysis is presented to determine the effects of different physical parameters arising in the system on temperature, nanoparticle concentration, and velocity profiles. As an illustration, the findings exhibit that increasing the modified diffusivity ratio increases the values of the nanoparticle volume fraction whereas, reducing the modified diffusivity ratio enhances the temperature distribution. A higher value of thermal Rayleigh number presents a significant involvement of buoyancy forces, potentially resulting in the development of convective currents. A higher Nield number indicates more effective heat transport from the solid surface to the nanofluid. Consequently, there is a minimal thermal difference between the solid surface and the bulk nanofluid. Effective heat transmission enhances the nanofluid ability to absorb heat and generates a more consistent dispersion of temperature inside the fluid. The performance of the designed algorithms of the artificial neural network, namely, the Levenberg – Marquardt algorithm, in the problem under consideration is evaluated and the methodology is found reasonably precise with the matching of order around 6 to 7 decimal places of accuracy.

X-ray imaging crystal spectrometer (XICS) diagnostic on the HL-3 tokamak

The construction of an X-ray imaging crystal spectrometer (XICS) diagnostic system on the HL-3 tokamak plays a crucial role in measuring core plasma parameter profiles, including ion temperature, electron temperature, rotational velocity, and impurity radiation profiles. This diagnostic system has been specifically designed to provide detailed and accurate data essential for understanding the behavior and characteristics of tokamak plasma. The resonance spectral line (w line of Ar XVII at 3.9494 Å) and its satellites of helium-like argon ions were chosen on the basis of the HL-3 parameter range. A spherically bent quartz crystal (1012) with a lattice constant of 2d = 4.562 Å, a curvature radius of Rc = 3.0 m, and a size of 10 cm (high) × 5 cm (wide) was mounted on an adjustable displacement platform in the XICS system. The position was adjusted in three dimensions (vertical, inclined, rotation) to effectively record the spectra of the helium-like argon ions. The XICS has a tangential angle of 49° for the toroidal direction in the magnetic axis. This layout accounts for 65.6 % of the toroidal rotation velocity component. The XICS system was set at an 11° poloidal angle in the mid-plane to cover a plasma range of 10 cm above to 50 cm below the mid-plane, which corresponds to the q = 1 surface of the HL-3 plasma (elongation κ > 1.8). This XICS layout produced a spectrum with poloidal and toroidal rotational contributions, requiring decoupling through data processing. In general, because the contribution of the poloidal rotation velocity is much smaller than that of the toroidal rotation velocity, it can be ignored. The XICS system offers a spatial resolution of ∼1.5 cm and a temporal resolution of 5–10 ms on the basis of a high-performance PILATUS3 × 900 K detector. The spectral resolution is λ/Δλ∼4×104, which satisfies the experimental measurement requirements. Preliminary results of ion and electron temperature profiles were obtained for the HL-3 tokamak.

TEMPORAL LINEAR STABILITY OF A CONVECTIVE ATMOSPHERIC PARCEL WITH AN AFFINE VELOCITY FIELD

In this article, we study the temporal linear stability of some class of convective atmospheric parcels, assuming an input affine velocity profile. The purpose is to compare the results to those obtained in our previous studies [1]. The assumption of an affine velocity profile led to the establishment of a satisfying base flow since the pressure is hydrostatic and the vertical gradient of the density is decreasing. Subsequently, the disturbance of our basic flow allowed us to obtain dispersion relations whose resolutions have given eigenfrequencies. Numerical analysis of these eigenfrequencies has shown that apparent gravity is not a destabilizing parameter, unlike the real gravity intensity and the entrainment rate, which are destabilizing parameters for the atmospheric cell in full ascent in the atmospheric boundary layer.

Agreement and Sensitivity of the Acceleration–Velocity Profile Derived via Local Positioning System

Sprint performance is commonly assessed via discrete sprint tests and analyzed through kinematic estimates modeled using a mono-exponential equation, including estimated maximal sprinting speed (MSS), relative acceleration (TAU), maximum acceleration (MAC), and relative propulsive maximal power (PMAX). The acceleration–velocity profile (AVP) provides a simple summary of short sprint performance using two parameters: MSS and MAC, which are useful for simplifying descriptions of sprint performance, comparison between athletes and groups of athletes, and estimating changes in performance over time or due to training intervention. However, discrete testing poses logistical challenges and defines an athlete’s AVP exclusively from the performance achieved in an isolated testing environment. Recently, an in situ AVP (velocity–acceleration method) was proposed to estimate kinematic parameters from velocity and acceleration data obtained via global or local positioning systems (GPS/LPS) over multiple training sessions, plausibly improving the time efficiency of sprint monitoring and increasing the sample size that defines the athlete’s AVP. However, the validity and sensitivity of estimates derived from the velocity–acceleration method in relation to changes in criterion scores remain elusive. To assess the concurrent validity and sensitivity of kinematic measures from the velocity–acceleration method, 31 elite youth basketball athletes (23 males and 8 females) completed two maximal effort 30 m sprint trials. Performance was simultaneously measured by a laser gun and an LPS (Kinexon), with kinematic parameters estimated using the time–velocity and velocity–acceleration methods. Agreement (%Bias) between laser gun and LPS-derived estimates was within the practically significant magnitude (±5%), while confidence intervals for the percentage mean absolute difference (%MAD) overlapped practical significance for TAU, MAC, and PMAX using the velocity–acceleration method. Only the MSS parameter showed a sensitivity (%MDC95) within practical significance (<5%), with all other parameters showing unsatisfactory sensitivity (>10%) for both the time–velocity and velocity–acceleration methods. Thus, sports practitioners may be confident in the concurrent validity and sensitivity of MSS estimates derived in situ using the velocity–acceleration method, while caution should be applied when using this method to infer an athlete’s maximal acceleration capabilities.

Aviation aspects of engine oil conveying copper tiny particles embedded in a rotating disk with a binary chemical reaction

Nanofluids have significant industrial applications and motivating heat transfer characteristics for various factors that contribute to the movement of nanofluids are essential significance. The aim of the present study focused on importance of heat transfer analysis on engine oil conveying copper nano particles embedded in a porous rotating disk with potential application in aerospace technology. In this model we considered magnetohydrodynamics, non-linear thermal radiation, thermophoresis and Brownian motion. The present investigation utilized copper nanoparticle and engine oil as a base fluid. The mathematical flow equations are transformed into ordinary differential equations (ODEs) by employing suitable self-similarity variables. The resultant ordinary differential equations are solved numerically by using the Midrich technique in the Maple software. The results are calculated to measure the impact of active parameters on velocity, temperature, concentration equations are presented graphically and in tabular form. Higher values of the magnetic field parameter the velocity profile decreased while the opposite tendency we noticed on energy profile. When increasing the radiation parameter values the energy profile increased. In both cases when increasing the magnetic field and radiation parameter values the Nusselt number profile increased. The research has important implications in a number of real-world situations. In particularly, the advancement of aircraft technology has presented manufacturers with new criteria and problems for the functioning of their devices. It is essential that, in order to guarantee the secure operation of aerospace machinery, the failure mechanisms be identified and the operational durability of critical structural components be improved as quickly as possible.

Influence of external magnetic field on nanofluid dynamics using a two-phase Lattice Boltzmann Mixture Model at low Reynolds numbers

This work examines the behavior of an external magnetic field-induced Al2O3-water nanofluid flow between two parallel plates, with a particular emphasis on low Reynolds number scenarios. Understanding the dynamics of magnetohydrodynamic (MHD) flows in applications including energy systems, cooling systems, and medicinal devices depends on solving this problem. For the first time, a new two-phase lattice Boltzmann method was used to simulate the flow in conjunction with the mixture model. This methodology was specifically designed for nanofluid flow in the presence of magnetic field. Three coupled transport equations for flow velocity, concentration of nanoparticles, and magnetic field intensity are solved using this method. Three various cases were examined numerically. By comparing the simulated velocity profiles with analytical solutions in the first case, model validation was accomplished, demonstrating a strong agreement with less than 1 % variance. The impact of different inflow nanoparticle volume fractions (0.05 and 0.01) on the velocity field at various Reynolds numbers (0.5, 1, 10) and Hartmann numbers (0, 10, 20) was investigated in the second case. The findings showed that for Reynolds numbers of 0.5, 1, and 10, respectively, the velocity magnitude dramatically fell by approximately 75 %, 68 %, and 30 % as the Hartmann number grew from 0 to 20. Alongside this decrease, vortices began to form at Hartmann numbers of 10 and 20. Furthermore, the influence of the magnetic field diminished as the Reynolds number increased from 0.5 to 10, resulting in a noticeable reduction in vortex intensity. In the third case, where the nanoparticle volume fractions at the inlet were closer (e.g., 0.03 and 0.02), the intensity of the vortices decreased compared to the second case. The study demonstrates the robustness of the proposed model and its applicability across scientific and engineering domains. The novelty lies in quantifying MHD effects on nanofluid flow and particle distribution using a two-phase lattice Boltzmann approach, offering more precise and efficient simulations than existing methods. The findings provide new insights into the interaction between magnetic fields and nanofluids, especially at low Reynolds numbers, and emphasize the critical role of nanoparticle distribution in flow dynamics.

Computational analysis of MHD hybrid nanofluid over an inclined cylinder: Variable thermal conductivity and viscosity with buoyancy and radiation effects

Due to their widespread use in engineering, hybrid nanofluids have been the primary focus of mathematical and physical research. Only the improvement of hybrid nanofluids’ variable heat conductivity and viscosity has been considered so far. Hybrid nanofluid flow across an inclined cylinder has many potential uses, including heat transfer and cooling in electrical devices, energy storage, refrigerants, and the automobile industry. Examining the effects of buoyant force, variable viscosity, variable thermal conductivity, mass suction, convective thermal conditions, and a magnetic field on the stagnation point flow of a Al2O3–Cu/H2O hybrid nanofluid in an inclined cylinder is our objective in this work. In order to find solutions to boundary-condition flow-describing partial differential equations, we turn them into ordinary differential equations using similarity transformations. We achieve this by employing a numerical strategy known as the fourth-order Runge–Kutta technique, which incorporates shooting techniques. A graphical representation of the findings emphasizes the influence of many physical parameters on flow dynamics. In addition, we address the influence of drag force and rate of heat transfer on various elements, such as the Biot parameter, magnetic variable, viscosity variable, and thermal conductivity variable. The mixed convection and magnetic parameters cause the velocity profile to rise while the temperature profile falls. The research’s results elucidate the cause behind the rise in thermal contour of hybrid nanofluids, which is seen when there is an increment in thermal conductivity, radiation parameter, and Biot number. The heat transfer rate exhibits a significant increase of 36.87% in the aiding flow scenario when a 2.0 mass suction is applied in conjunction with a 0.01 hybrid nanofluid, as compared to the conventional fluid. In the scenario of opposing flow, the heat transfer rate exhibits a significant increase of 36.96% when compared to that of ordinary fluid. Heat transfer increases 43.00% when Rd increases from 0.1 to 0.5 for both assisting and opposing flow.

Velocity profile shapes in Alcator C-Mod plasmas

Abstract Toroidal rotation velocity spatial profiles ( r / a < 0.8) have been obtained from C-Mod over a wide range of operational conditions, including H-mode, I-mode, ICRF-heated L-mode and Ohmic L-mode (LOC and SOC), and in plasmas with ITBs, LH wave injection and MCFD. Peaked, flat and hollow rotation profiles have been observed. In H- and I-mode plasmas, generally with co-current peaked profiles, the peaking is correlated with temperature profile peaking, and both increase with toroidal magnetic field (decrease with ρ ∗ ). Any dependence on density peaking is unclear. For Ohmic L-mode discharges, with LOC, the velocity profiles are usually flat and most often directed co-current, while with SOC the profiles are hollow, mostly co-current at the edge and counter-current in the core. Both of these Ohmic rotation states exist with matched density and temperature profiles (and gradients), indicating that neither gradient is relevant during rotation reversals. For plasmas with LH wave injection and discharges with ITBs, the velocity profiles are hollow while the density and temperature profiles exhibit substantial peaking. Broadly speaking for all operational regimes, there is no unifying ordering of the velocity gradient with plasma parameters.

Mapping the Distribution of the Magnetic Field Strength along the NGC 315 Jet

We study magnetic field strengths along the jet in NGC 315. First, we estimated the angular velocity of rotation in the jet magnetosphere by comparing the measured velocity profile of NGC 315 with the magnetohydrodynamic jet model proposed by Tomimatsu and Takahashi. Similar to the case of M87, we find that the model can reproduce the logarithmic feature of the velocity profile and suggest a slowly rotating black hole magnetosphere for NGC 315. By substituting the estimated Ω F into the jet power predicted by the Blandford–Znajek mechanism, we estimate the magnetic field strength near the event horizon of the central black hole as 5 × 103 G ≲ B H ≲ 2 × 104 G. We then estimate magnetic field strengths along the jet by comparing the spectral index distribution obtained from very long baseline interferometry (VLBI) observations with a synchrotron-emitting jet model. Then we constrain the magnetic field strength at a deprojected distance z from the black hole to be in the range 0.06 G ≲ B(z) ≲ 0.9 G for 5.2 × 103 r g ≲ z ≲ 4.9 × 104 r g , where r g represents the gravitational radius. By combining the obtained field strengths at the event horizon and the downstream section of the jet, we find that the accretion flow at the jet base is consistent with a magnetically arrested disk. We discuss a comparison of the jet power and the magnetic flux anchored to the event horizon in NGC 315 and M87.

Modeling temporal dynamics of a radiant Casson fluid near a steeped plate emitting heat and mass fluxes

AbstractIn today's rapidly advancing world, more deliberate development and implementation of energy‐efficient thermal management systems is emergent. In industrial and engineering contexts, the regulation of heat and mass transfer phenomena is heavily swayed by factors such as heat and mass fluxes, and wall temperature, and concentration levels. In cryogenic containers, understanding heat flux and wall temperature is essential for maintaining ultra‐low temperatures over extended periods. In this context, our paper embarks on modeling the transient dynamics of a radiant Casson fluid adjacent to a steeped plate, which is featured by its emission of both heat and mass fluxes. The plate is under two thermal conditions, namely uniform wall temperature (UWT) and uniform heat flux (UHF), which are crucial in modulating both upward and downward heat transport processes. The Laplace transform (LT) technique yields close‐form solutions for the model's governing equations. The distribution of flow and salient physical quantities are graphed and elucidated in response to intricate physical parameters. A comparative graphical analysis of UWT and UHF scenarios reveals stark differences. Notably, the fluid's flow rate appears considerably amplified in the UWT scenario compared to the UHF one. Furthermore, the UHF setting profoundly influences the heat and mass transportation within the fluid's flow realm. A pronounced Casson parameter tends to thin out the velocity profile. Concurrently, a heightened radiation parameter results in a reduction in fluid temperature. The theoretical framework explored in our study is not just an academic exercise but holds tangible applicability across varied sectors. This spans from rocket chamber cooling, where fine‐tuned heat flux conditions are paramount for safeguarding operations, to industries like cosmetics and food processing, which demand meticulous thermal regulation to ensure product excellence.

Predicting heat transfer Performance in transient flow of CNT nanomaterials with thermal radiation past a heated spinning sphere using an artificial neural network: A machine learning approach

An efficient heat transfer phenomenon using nanofluid have greater challenges in various industries, engineering application the recent trend. Keeping this in present scenario, this study aims to optimize the heat transmission rate in the magnetized flow of nanomaterials through a rotating, spinning sphere. The heat transfer phenomena in the time-dependent fluid are enhanced by the incorporation of nonlinear radiation and a variable heat source. Additionally, the free convective flow is influenced by the effects of thermal buoyancy and a transverse magnetic field. The proposed model along with several factors is standardized through adequate transformation rules. Further, shooting-based Runge-Kutta technique is adopted with the help of built-in MATLAB function bvp4c for the solution of the transformed system. The prime focus of the proposed work is the optimizing heat transfer rate combined with regression analysis using artificial neural network and then it uses Levenberg Marquardt algorithm with well-posed training, testing, and validation data. The error analysis also presented briefly and the variation of characterizing parameters is depicted via graphs. Further, the important outcomes are; the particle concentration of carbon nanotubes contributes to decelerating the velocity profiles, leading to an increase in boundary layer thickness. In contrast, increasing magnetization has the opposite effect. Both nonlinear radiative heat and an additional heat source enhance the heat transfer phenomenon.

Thermal analysis in unsteady oscillatory Darcy blood flow through stenosed artery

This study aims to provide an extensive overview of the consequences of heat source and thermal radiation on blood flow in stenosed arteries through Casson fluid. We examine the behaviour of an unsteady non-Newtonian fluid under oscillatory Darcy flow. This analysis explores the impact of blood flow in the stenosed arteries on the momentum and energy profiles of the Casson fluid. In addition, this study examines a parametric analysis to illustrate the impact of the Nusselt number and Casson parameter. Higher values of the thermal radiation and Casson-Viscous parameters result in enhanced velocity fields. The Brinkman model accurately represents the resistance to flow caused by the porous material, known as Darcy resistance. The inner space of the coronary artery generates cholesterol-rich fatty plaques and blood clots that block the artery, simulating the diseased condition of blood circulation in this study. We employ a set of non-dimensional variables to convert the governing equations of the current flow into dimensionless partial differential equations. Analytical methods have derived a solution for the studied problem. The discovery is pertinent to the natural circulation of blood through coronary arteries, which are highly porous. A particular artery pathology creates a permeable structure within the arterial lumen. The current study demonstrates that blood flow may be manipulated by adjusting the intensity of the external magnetic field, while the temperature of the blood can be managed by either increasing or decreasing its thermal conductivity. The graphical representation demonstrates the impact of different physical parameters on velocity, temperature, and concentration profiles. The significant results of the current studies are that, the fluid velocity diminishes with rising magnetic and Biot numbers but exhibits an increase when considering the Darcy number and Hall parameter. There is a gentle increase in the wall shear stress as the Casson parameter (β) increases from 0.1 to 0.3. For β= 0.3, the percentage change along the axial direction (x) is more pronounced. This is because the wall shear stress is proportional to the number of Casson parameters.

Stability of a viscous liquid film flowing down an inclined plane with respect to three-dimensional disturbances

An analysis is presented for the stability of a viscous liquid film flowing down an inclined plane with respect to three-dimensional disturbances under the action of gravity and surface tension. Using momentum-integral method, the nonlinear free surface evolution equation is derived by introducing the self-similar semiparabolic velocity profiles along the flow (x- and y-axis) directions. A normal mode technique and the method of multiple scales are used to obtain the theoretical (linear and nonlinear stability) results of this flow problem, which conceive the physical parameters: Reynolds number Re, Weber number We, angle of inclination of the plane θ and the angle of propagation of the interfacial disturbances ϕ. The temporal growth rate ωi+ and second Landau constant J2, based on which various (explosive, supercritical, unconditional, subcritical) stability zones of this flow problem are categorized, contain the shape factors B and β owing to the non-zero steady basic flow along the y-axis direction. A novel result which emerges from the linear stability analysis is that for any given value of Re, We and θ, any stability that arises in two-dimensional disturbances (ϕ = 0) must also be present in three-dimensional disturbances. For ϕ = 0, there exists a second explosive unstable zone (instead of unconditional stable zone) after a certain value of Re (or θ) due to the involvement of B and β in the expression of J2. This explosive unstable zone vanishes after a certain value of ϕ depending upon the values of Re, We and θ, which confirms the stabilizing influence of ϕ on the thin film flow dynamics irrespective of the values of Re, We and θ.

Stokes flow past an array of circular cylinders through slip-patterned microchannel using boundary element method

Two-dimensional viscous incompressible, pressure-driven, creeping flow at low Reynold's number (Re ≪ 1) around a series of circular cylinders in a slip-patterned rectangular microchannel is investigated numerically by using the boundary element method (BEM) based on a non-primitive variables approach. The non-primitive variables approach refers to the combination of stream function and vorticity variables. The Stokes equations are used to govern the flow of creeping fluid through a microchannel. We consider the alteration of the slip on both the upper and lower surfaces of the microchannel maintain the same phase (i.e., in-phase configuration). Here, the slip boundary condition refers to Navier's slip boundary condition. We considered both small as well as large patterned slip on both surfaces of the microchannel. Moreover, we have assumed that a number of cylinders of equal diameter are present in the in-line configuration in the path of flow. We studied streamlines, velocity profiles, pressure gradients, and the shear stresses with varied slip-length, and the radius of the cylinder, to get a complete comprehension of flow dynamics. We observed that the velocity and shear stress profiles exhibit significant variability in the case of fine slip patterning. Additionally, the proposed investigation holds several potential applications, such as drug capsule delivery systems, hemodynamics, bio-MEMS technology, and so forth.

Dynamics of thermal radiatively Jeffrey fluid through an annulus region between two flexible tubes with entropy generation

Endoscope is a very important tool for medical diagnosis and they have many clinical applications. The endoscope now is a very important tool used for determining real reasons responsible for many problems in the human organs in which the fluid is transported by peristaltic pumping such as the stomach, small intestine, etc Therefore, this paper discusses the influence of an endoscope on the peristaltic flow of a Jeffery fluid in an annulus by considering the entropy generation. The inner tube which is uniform and rigid fulfilled the slip conditions, while the outer tube having a sinusoidal wall has a no-slip condition. The impacts of thermal radiation and viscous dissipation are also considered in the energy equation. The flow analysis has been developed for low Reynolds number and long wavelength approximation. The analytical solution for velocity, pressure gradient, temperature, streamlines, entropy generation, and Bejan number is obtained using the perturbation method, and then the obtained results are plotted to see the influence of different physical parameters. The major outcomes disclosed that the velocity profile decreases near the region of the inner tube due to the slip parameter and the inner tube radius. However, it increases due to the inner tube velocity and amplitude ratio. The temperature distribution rises with the Brinkman number. On the other hand, it declined for the radiation parameter. Furthermore, the entropy generation increases for the Brinkman number, but the Bejan number decreases for the Brinkman number. The present study has application in endoscopes, which is important to diagnose problems in internal organs. Also, the variation of pressure gradient helps to maintain the flow rate which is essential during the insertion of the catheter into the artery.

Eulerian approach for erosion induced by particle-laden impinging jets

Particle dispersion and erosion play an important role in various engineering applications, particularly in impinging jet flows. This study presents a new Eulerian method for characterizing these phenomena in axisymmetric, laminar, and turbulent jets, impinging and transiently eroding a flat wall. The Eulerian mass and momentum conservation equations are solved assuming a one-way coupling between the flow and the particles. The carrier flow boundary layer velocity profiles in the laminar case are validated with analytical solutions. The particle calculation involves two stages, incident and reflected particles, connected via a restitution model. The reflected particles’ results offer insights into secondary erosion areas but are not used for the main erosion calculations. Subsequently, erosion at the eroded surface is computed using an empirical erosion model, followed by the displacement of computational nodes using the linear-elastic, small-strain deformation equations, all of which are solved transiently. The solutions reveal the spatial particle concentrations and momentum for different Stokes numbers: smaller Stokes particles follow the carrier flow streamlines, medium Stokes particles deviate, forming a W-shaped erosion profile, while the largest Stokes particles create a U-shaped profile. This numerical model offers a computationally efficient framework for CFD-based transient erosion calculation due to its Eulerian implementation.

Generative Adversarial Networks-Based Ground-Motion Model for Crustal Earthquakes in Japan Considering Detailed Site Conditions

ABSTRACT We develop a ground-motion model (GMM) for crustal earthquakes in Japan that can directly model the probability distribution of ground-motion acceleration time histories based on generative adversarial networks (GANs). The proposed model can generate ground motions conditioned on moment magnitude, rupture distance, and detailed site conditions defined by the average shear-wave velocity in the top 5, 10, and 20 m (VS5, VS10, and VS20) and the depth to shear-wave velocities of 1.0 km/s and 1.4 km/s (Z1.0 and Z1.4). We construct the neural networks based on styleGAN2 and introduce a novel neural network architecture to generate ground motions considering the effect of source, path, and such detailed site conditions. The resulting 5% damped spectral acceleration from the proposed GMM is consistent with empirical GMMs in terms of magnitude and distance scaling. The proposed GMM can also generate ground motions accounting for the shear-wave velocity profiles of surface soil with different magnitudes and distances and represent characteristics that are not explained solely byVS30.

Numerical investigation on the VIV response of the flexible cylindrical structures subjected to non-linearly varying shear flow

Vortex-induced vibration (VIV) of flexible cylinders is an important phenomenon in ocean structures, which may cause fatigue damage and structural failure of offshore structures. Much literature has extensively explored VIV of flexible cylinders under various flow conditions, such as uniform and linearly varying shear flow. However, real scenarios in most cases involve non-uniform, non-linearly varying shear flow profiles. Hence, it is important to investigate the VIV response of the flexible cylindrical structures subjected to non-linearly varying shear flow profiles. This study employs a wake oscillator model (WOM) that simulates the VIV response of the flexible cylinder under the action of non-linearly varying shear flow velocity profiles. The flexible cylinder subjected to linearly varying sheared flow velocity profiles not only overpredicts but also underpredicts the VIV responses compared to the non-linearly varying sheared flow profile, which represents the real scenario. The VIV mode number for the flexible cylinder subjected to non-linear shear flow was found to have a non-linear relationship with that of linear shear flow. The VIV response of the flexible cylinder subjected to a linearly varying shear flow profile exhibits more travelling wave behaviour compared to non-linear shear flow. The location of the maximum VIV response of the structure having the same aspect ratio (L/D) and shear parameter (β), was different for linear and non-linear flow profiles across the span. The time and frequency domain responses showed a shift in the frequency band. The results obtained from the numerical simulations give better insights into the vibrational behaviour of flexible cylinders in realistic flow environments.