Three-dimensional Fluid Flow Research Articles

Investigation on metal vapor characteristics and keyhole/melt pool dynamics in high-power laser welding with side gas flow

High-power laser welding processes involve intense interactions between the laser beam and the base material, resulting in severe welding defects such as humping, spattering, and undercutting. Utilizing side gas flow may provide an effective approach for minimizing these defects. However, the effects of side gas flow on the dynamic behavior and weld formation necessitate further investigation. In this study, an innovative analysis of metal vapor characteristics and keyhole/melt pool dynamics in high-power laser welding with side gas flow is presented, combining experimental and simulation results. A three-dimensional transient fluid flow model was developed, uniquely integrating an adaptive heat source, evaporation-condensation processes, and metal vapor energy attenuation to provide a novel perspective on the effects of side gas flow in high-power laser welding. The results display that side gas flow could suppress plasma, increase thermal input to the melt pool, and intensify the flow of liquid metal toward the pool bottom during high power laser welding, thereby enhancing weld seam penetration. The numerical results indicate that variations in flow rate significantly impact metal vapor morphology, with higher flow rates reducing both the average area and height of the metal vapor and effectively suppressing the size of metal vapor/plasma. When the side gas flow rate is 20 l/min, with the gas flow impact point located at the keyhole opening and the nozzle height set to 3 mm, the side gas flow significantly enhances the depth-to-width ratio of the weld seam in 316L stainless steel laser welding. This work can provide guidance for suppression of weld defects in high-power laser welding of medium-thick steel components, which has important theoretical significance and application value.

Modelling of cracking during beam oscillation laser welding of a creep-resistant nickel alloy

During high power laser welding of Inconel 740H, horizontal solidification cracks form at locations between approximately 70–80% of the weld depth. With the integration of circular beam oscillation, the laser energy density distribution and underlying thermo-mechanical conditions were altered. By coupling three-dimensional heat transfer, fluid flow, and stress modelling tools, the role that circular beam oscillation plays in the formation of the strain rates and stresses driving this cracking phenomenon was identified. While the addition of a circular oscillation pattern appeared to lower the stress levels along the solidification front, it did not eliminate the appearance of horizontal cracking. Only when the beam amplitudes reached 1.6 mm did solidification cracking disappear, but the weld depths were also significantly reduced.

Numerical investigation of three-dimensional incompressible fluid flow in curved elastic tube

Numerical investigation of three-dimensional incompressible fluid flow in curved elastic tube

A new higher-order super compact finite difference scheme to study three-dimensional non-Newtonian flows

This work introduces a new higher-order accurate super compact (HOSC) finite difference scheme for solving complex unsteady three-dimensional (3D) non-Newtonian fluid flow problems. As per the author's knowledge, the proposed scheme is the first ever developed higher-order compact finite difference scheme to solve 3D non-Newtonian flow problems. The proposed scheme is fourth-order accurate in space and second-order accurate in time, utilizing only seven adjacent grid points at the (n+1)th time level for the finite difference discretization. A time-marching methodology is employed with pressure calculated via a pressure-correction strategy based on the modified artificial compressibility method. Using the power-law viscosity model, we tackle the benchmark problem of a 3D lid-driven cavity, systematically analyzing the varied rheological behavior of shear-thinning (n = 0.5), shear-thickening (n = 1.5), and Newtonian (n = 1.0) fluids across different Reynolds numbers (Re=1,50,100,200). Both Newtonian and non-Newtonian results are carefully investigated in terms of streamlines, velocity variation, pressure distributions, and viscosity contours, and the computed results are validated with the existing benchmark results. The findings demonstrate excellent agreement with the existing results. It is found that for shear-thinning fluid (n = 0.5), u velocity is higher near the top moving wall than the case of Newtonian (n = 1.0) and shear-thickening fluid (n = 1.5) for all Re values. This extensive analysis, using the new HOSC scheme, not only increases our understanding of non-Newtonian fluid behavior but also provides a robust foundation for future research and practical applications.

Numerical Study of the 3D MHD Radiative Flow of Williamson Nanofluid with Variable Characteristics Over a Double Stretching Sheet

The current study investigates the influence of variable thermal conductivity and mass conductivity on 3D MHD. The significance of this study lies in mass diffusion on a three-dimensional Williamson nanofluid fluid flow over a double stretched sheet. When thermal radiation and Hall current is present, the heat transfer process is explored to see how chemical reactions affect heat and mass transmission. Additional phenomena, such as momentum slip and convective boundary conditions, contribute to the model's uniqueness. The problem formulation becomes ordinary differential equations with application of the Von Karman similarity variable. Use of the bvp4c function in yields a numerical solution for the system of differential equations. Using MATLAB’s bvp4c function, a numerical solution to the differential equation system is obtained. A graphic is used to discuss the overall result of several metrics compared to the involved profiles. It is believed that as temperature-dependent thermal conductivity and viscosity increase, so does the temperature field. When the Williamson fluid and magnetic parameters rise, the velocity field decays in the x- and y-axis directions. To support the identified issue, a comparison between the current inquiry and a previously published work is also included.

Effect of oscillation parameters on weld surface morphology during laser beam oscillation welding of stainless steel

During laser beam oscillation welding (LBOW), the weld surface morphology is important because it influences the appearance of the workpiece and reflects the welding quality, and the oscillation parameters have an important effect on the weld surface morphology. Therefore, a combination of experimental research and numerical simulation is conducted to investigate the influence of oscillation parameters, including oscillation mode, oscillation frequency, and oscillation amplitude, on the weld surface morphology during LBOW. The calculation encompasses the oscillation trajectory, combined velocity, and energy distribution on the weld surface, varying with different oscillation parameters. A three-dimensional heat transfer and fluid flow model with the oscillation heat source is established to simulate the temperature and fluid flow behavior inside the weld pool. When the heat input is constant, an increase in oscillation frequency results in a decrease in weld width and a smoother surface. As the oscillation frequency increases, the weld width decreases, the surface becomes smooth, and the energy distribution on the weld surface becomes more uniform. The fact that the period of the surface pattern is almost equal to the oscillation period indicates a direct correlation between the formation of weld surface pattern and the oscillation trajectory in LBOW. Among all the oscillation modes, the minimum combined velocity which is equal to the welding velocity occurs at the inflection point in the linear oscillation mode, and the variation in combined velocity of the laser beam is the smallest for circular oscillation mode. The surface pattern is primarily influenced by the oscillation trajectory and fluid flow within the weld pool. Under conditions of lower oscillation frequencies or larger oscillation amplitudes, the fluid flow is weaker, and the surface pattern is primarily influenced by the oscillation trajectory. Conversely, when the fluid flow is stronger, the surface pattern is mainly determined by the fluid flow within the weld pool under conditions of higher oscillation frequencies or smaller oscillation amplitudes. This study explains the formation mechanisms of weld surface patterns and provides insights and guidance for selecting optimal oscillation parameters in LBOW.

A Multivariable Numerical Investigation of Wavy-Based Microchannel Heat Sink Geometry Towards Optimal Thermal Performance

Abstract This research provides a comprehensive multivariable comparative investigation of the effect of various microchannel configurations on their thermal performance. Three-dimensional fluid flow and heat transfer simulations are performed with different arrangements of the channel's width tapering and cross-sectional aspect ratio with an emphasis on the synergistic proven effects of geometrical parameters in innovatory combinations. Results confirm that wavy channels are significantly superior to straight channels in terms of thermal performance due to the creation of secondary flow (Dean Vortices), which improves the processes of advective mixing and, therefore, overall heat transfer characteristics with minimal pumping power penalty. Width-tapering of wavy channels also shows better thermal resistance than untapered wavy channels producing almost 10 percent thermal resistance improvement. The study indicates a significant dependency of thermal performance on the cross-sectional aspect ratio of the channel which suggests that there are ideal tapering and aspect ratio conditions. An innovative wavy-tapered microchannel heat sink has been introduced, featuring an optimal parametric configuration and directionally alternating coolant flow. This design results in additional thermal resistance improvement by 15% and significantly improves substrate temperature distribution uniformity. Overall, the results demonstrate the superior potential of the configuration for high-end electronics cooling tasks. These results provide interpretive insight into microchannel heat sink design and optimization.

Effect of flow modifiers on the fluid flow characteristics in a slab caster tundish

ABSTRACT In a slab caster tundish, controlling liquid steel flow is of paramount importance for clean steel production. A conventional tundish design consists of a pouring box, a weir and a dam. To improve the overall performance of a 40 ton slab caster tundish, three different arrangements by incorporating additional flow modifiers have been examined. A three-dimensional steady state fluid flow model has been developed using a RANS (Reynolds-Averaged Navier-Stokes) approach. Subsequently, transient scalar-transport equations were solved to obtain the C-curve of the tundish. A different approach has been followed to evaluate the inlet boundary condition to mimic the process conditions more accurately. The CFD predictions were validated with the results of the water model. Mean residence time, dead volume fraction and flow structures have been considered for evaluating tundish performance. All the proposed configurations have shown improvements in comparison to the base case. The mean residence time of the fluid was found to be the highest for the case having two pairs of weir and dam. However, the insights derived from the flow structures specifically plug flow in zone 2 and near the tundish outlet region suggest that that having a single weir and two dams is the optimal choice.

Exploring Unsteady Three-Dimensional Casson Fluid Flow through a Stretching Surface with Heat Source/Sink: A Numerical Investigation

This research aims to examine the effects of a heat source or sink and viscous dissipation on an MHD unsteady three-dimensional Casson fluid flow across a stretched sheet. Using similarity transformations, the governing partial differential equations are transformed into coupled ordinary differential equations, which are then solved numerically in Matlab. The numerical findings for several physical parameters that impact velocity and temperature profiles are described in tables and graphs. The interesting finding are recorded as follows: When the Magnetic parameter increases, the skin friction coefficient increases along x and z directions, but when the Casson parameter lowers, it decreases. The Nusselt number increases with the enhancement of viscous dissipation parameter and heat source or sink parameter. Understanding the behavior of non-Newtonian fluids in the presence of heat transfer is crucial in a number of domains, including chemical engineering, biomechanics, and material processing. These applications might benefit from this kind of study.

Numerical investigation of fluid flow behavior in steel cord with lattice Boltzmann methodology: The impacts of microstructure and loading force.

Steel cord materials were found to have internal porous microstructures and complex fluid flow properties. However, current studies have rarely reported the transport behavior of steel cord materials from a microscopic viewpoint. The computed tomography (CT) scanning technology and lattice Boltzmann method (LBM) were used in this study to reconstruct and compare the real three-dimensional (3D) pore structures and fluid flow in the original and tensile (by loading 800 N force) steel cord samples. The pore-scale LBM results showed that fluid velocities increased as displacement differential pressure increased in both the original and tensile steel cord samples, but with two different critical values of 3.3273 Pa and 2.6122 Pa, respectively. The original steel cord sample had higher maximal and average seepage velocities at the 1/2 sections of 3D construction images than the tensile steel cord sample. These phenomena should be attributed to the fact that when the original steel cord sample was stretched, its porosity decreased, pore radius increased, flow channel connectivity improved, and thus flow velocity increased. Moreover, when the internal porosity of tensile steel cord sample was increased by 1 time, lead the maximum velocity to increase by 1.52 times, and the average velocity was increased by 1.66 times. Furthermore, when the density range was determined to be 0-38, the pore phase showed the best consistency with the segmentation area. Depending on the Zou-He Boundary and Regularized Boundary, the relative error of simulated average velocities was only 0.2602 percent.

On the Darcy–Forchheimer flow of carbon nanotubes nanofluid across a stretching surface for the impact of heat source/sink and Ohmic heating

This research leads to carrying out the productivity and the efficiency of the carbon nanotubes (CNTs) that have extensive applications in solar collectors. Due to the superior thermal as well as electrical properties, the use of CNTs has an important contribution to the nanotechnology revolution. Therefore, owing to the aforementioned vital points, this investigation intended to put forth the thermophysical properties of both single and multi-walled CNT nanofluids past a stretching surface. Additionally, an electrically conducting nanofluid flow phenomenon enriches due to the inclusion of dissipation (Ohmic heating) and external heat source/sink. The dimensional form of the three-dimensional fluid flow phenomena is transformed to a non-dimensional form with the use of similarity transformation and further numerical procedure is implemented to solve the nonlinear governing equations. The substantial significance of the characterizing parameters is presented briefly via figures and the comparative analysis with the earlier investigation is deployed through the table. However, the main findings of this study are as follows: A significant attenuation in the shear rate is marked for the enhanced inertial drag but it augments for the augmented values of the magnetization; further, particle concentrations of both the CNTs favor accelerating the fluid momentum as well as temperature distribution.

Vortex line entanglement in active Beltrami flows

Over the last decade, substantial progress has been made in understanding the topology of quasi-two-dimensional (2-D) non-equilibrium fluid flows driven by ATP-powered microtubules and microorganisms. By contrast, the topology of three-dimensional (3-D) active fluid flows still poses interesting open questions. Here, we study the topology of a spherically confined active flow using 3-D direct numerical simulations of generalized Navier–Stokes (GNS) equations at the scale of typical microfluidic experiments. Consistent with earlier results for unbounded periodic domains, our simulations confirm the formation of Beltrami-like bulk flows with spontaneously broken chiral symmetry in this model. Furthermore, by leveraging fast methods to compute linking numbers, we explicitly connect this chiral symmetry breaking to the entanglement statistics of vortex lines. We observe that the mean of linking number distribution converges to the global helicity, consistent with the asymptotic result by Arnold [In Vladimir I. Arnold – Collected Works (ed. A.B. Givental, B.A. Khesin, A.N. Varchenko, V.A. Vassiliev & O.Y. Viro), pp. 357–375. Springer]. Additionally, we characterize the rate of convergence of this measure with respect to the number and length of observed vortex lines, and examine higher moments of the distribution. We find that the full distribution is well described by a k-Gamma distribution, in agreement with an entropic argument. Beyond active suspensions, the tools for the topological characterization of 3-D vector fields developed here are applicable to any solenoidal field whose curl is tangent to or cancels at the boundaries of a simply connected domain.

A hybrid approach towards evaluation of average heat transfer coefficient in twin-roll strip casting mold

Continuous casting stands out as one of the most efficient and productive methods for producing billets, slabs, or thin sheets while conserving energy. Understanding the solidification dynamics and achieving defect-free sheets in continuous casting necessitates the accurate prediction of heat transfer coefficient (HTC) at the mold metal interface. Accurate prediction of HTC helps in selecting process parameters such as superheat temperature and casting velocity, which directly affect the production rate and quality of the cast component. Determining the HTC is a complex process, as it is influenced by various process parameters such as casting size, casting speed, superheat temperature, surface roughness, type of water used as a coolant, nozzle design and wettability. Therefore, the present study proposed a hybrid approach for finding HTC in a twin roll strip casting mold through a solidified shell shape, which is influenced by the factors affecting the heat transfer at the mold-metal interface. This approach integrates the experimental and simulation investigations. The numerical investigation used a three-dimensional coupled fluid flow and heat transfer equations with an assumed range of HTC (100–2000 W/(m2K)). The solidified shell shape for different HTCs was compared with the experimental solidified shape form at the outer wall of the mold using the solidification criteria. Results indicate that the initial HTC range of 100–1000 W/(m2K) does not lead to blockage of the graphite mold outlet. However, as HTC values approach 1000 W/(m2K) to 1400 W/(m2K), the melt obstructs the mold exit based on solidification criteria. The HTC values (1350 ± 150 W/(m2K)) obtained from the proposed methodology for mold, align well with the HTC values (1183 ± 593 W/(m2K)) calculated using lamellar spacing of the Al-Mg2Si composite microstructure. This hybrid approach presents a novel and straightforward method for determining HTC, offering accurate predictions that can enhance the precision of continuous casting models and provide a more nuanced understanding of solidification behavior.

Data-driven nonlinear parametric model order reduction framework using deep hierarchical variational autoencoder

A data-driven parametric model order reduction (MOR) method using a deep artificial neural network is proposed. The present network, a least-squares hierarchical variational autoencoder (LSH-VAE), is capable of performing nonlinear MOR for the parametric interpolation of a nonlinear dynamic system with a significant number of degrees of freedom. LSH-VAE differs from existing networks in two major respects: a deep hierarchical structure and a hybrid weighted, probabilistic loss function. The enhancements result in significantly improved accuracy and stability compared with conventional nonlinear MOR methods, autoencoders, and variational autoencoders. In LSH-VAE, the parametric MOR framework is based on the spherically linear interpolation of the latent manifold. The present framework is validated and evaluated on three nonlinear and multiphysics dynamic systems. First, the present framework is evaluated on the fluid–structure interaction benchmark problem to assess its efficiency and accuracy. Then, a highly nonlinear aeroelastic phenomenon, limit cycle oscillation, is analyzed. Finally, the framework is applied to three-dimensional fluid flow to demonstrate its capability to efficiently analyze a significantly large number of degrees of freedom. The superior performance of LSH-VAE is emphasized by comparing its results against those of widely used nonlinear MOR methods, a convolutional autoencoder, and β\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta $$\\end{document}-VAE. The proposed framework exhibits significantly enhanced accuracy compared with that of conventional methods, while the computational efficiency continues to remain significantly higher.

INSIGHT INTO THE IMPACT OF MELTING HEAT TRANSFER AND MHD ON STAGNATION POINT FLOW OF TANGENT HYPERBOLIC FLUID OVER A POROUS ROTATING DISK

Melting heat transfer plays a crucial role in many industrial devices, including heat exchangers, air conditioning, and metal casting. Considering these uses the heat transmission in three-dimensional tangent hyperbolic fluid flow is evaluated. The effects of magnetohydrodynamics (MHD), Ohmic heating, porous medium and melting heat transfer at the boundary are applied to the stretching rotating disk. The governing equations are transformed into a nondimensional form after applying a similarity transformation. The simplified ordinary differential equations contain various dimensionless terms, and the results of these variables are obtained by the bvp4c method. The graphical and tabular results for existing parameters are displayed. For the validation of our results, a comparison is done. From the outcomes, it is noticed that velocity and temperature profiles are enhanced with melting heat transfer at the boundary. The porosity parameter reduces the velocity of the tangent hyperbolic fluid. Moreover, the Eckert number demonstrates the dual nature of temperature profiles.

Layer-based Simulation for Three-Dimensional Fluid Flow in Spherical Coordinates

Layer-based Simulation for Three-Dimensional Fluid Flow in Spherical Coordinates

Modeling of a Three-Dimensional Incompressible Fluid Flow in a Turbulent Boundary Layer in a Diffuser

Modeling of a Three-Dimensional Incompressible Fluid Flow in a Turbulent Boundary Layer in a Diffuser

Three-dimensional rotatory micropolar fluid flow between two stretchable disks with Maxwell–Cattaneo law

Three-dimensional rotatory micropolar fluid flow between two stretchable disks with Maxwell–Cattaneo law

Effect of porous density of twisted tape inserts on heat transfer performance inside a closed conduit

This study examines the impact of varying the porosity density of twisted tape inserts (TTI) on the temperature distribution, fluid velocities, heat transfer coefficients (HTC), Nusselt numbers (Nu), turbulent kinetic energy (TKE), and performance from 5000 to 12500 Reynolds numbers (Re). The entire process involved the design of TTIs and double pipe heat exchangers using SolidWorks. Subsequently, a three-dimensional fluid flow model was employed to solve equations related to energy mass, energy, and momentum within the ANSYS Fluent interfaces. The findings highlight the noteworthy impact of high porosity TTIs, which consistently reduce temperature spans, increase fluid velocities, and greatly HTC and Nu when compared to low porosity TTI, typical TTI, and plain tubes. Furthermore, high porosity TTI significantly increases TKE, indicating increased fluid turbulence and higher heat transfer efficiency, especially at Re = 12500. The assessment of PEC emphasizes the superiority of high porosity TTI, demonstrating their significant performance increase potential of over 6.44 % over low porosity TTI and a staggering 62.5 % above typical TTI. In conclusion, high porosity TTI emerges as a potential solution for improving heat transfer efficiency and overall system performance in a variety of industrial applications, promising enhanced energy efficiency and superior performance.

Keyhole mode wobble laser welding of a nickel base superalloy - Modeling, experiments, and process maps

Keyhole mode wobble laser welding is gaining increasing acceptance due to its ability to bridge gaps, refine microstructure, and enhance the mechanical properties of welds. However, the impact of amplitude, frequency, welding speed, laser beam power, and beam radius on the heat flux distribution, melting pattern, and three-dimensional temperature field is not well understood. To address this need, here we report a combined experimental and computational study to investigate the effects of the key wobble welding parameters on the energy distribution impinging on the welding track, keyhole formation, three-dimensional fluid flow and heat transfer during wobble laser welding of Inconel 740H. The modeling results were rigorously tested using experiments in which the welding speed, laser power, and wobble amplitude and frequency were varied. A bimodal power density distribution with higher power density near the edge than in the middle of the track occurred when the wobble amplitude significantly exceeded the laser beam diameter. A high wobble amplitude resulted in a wide and shallow pool while the wobble frequency used in this work did not significantly impact the fusion zone geometry. A set of process maps were constructed to understand the role of wobble laser parameters in achieving a desirable fusion zone geometry during keyhole mode wobble laser welding. Finally, wobble laser welding with a high amplitude was found to favor rapid solidification and the formation of finer solidification microstructure.