Fluid Motion Research Articles

Study on the ice-water interaction problem based on MPS-NDEM coupling model

Ice-water coupling is a unique fluid-solid interaction problem characterized by collisions and hydrodynamic interaction between multiple bodies, accompanied by significant changes in the free surface. This paper presents a novel numerical model that achieves two-way coupling between the moving particle semi-implicit (MPS) method and the non-smooth discrete element method (NDEM) to simulate ice-water interactions. The MPS method is employed to model fluid motion, while the NDEM is applied to simulate the motion and collision of ice floes. The improved MPS method presented in this study, based on our previous research, addresses several issues found in the traditional MPS method. To improve the computational efficiency, the domain decomposition method is implemented to parallel the fluid solver and the AMG preconditioned GMRES iterative solver is selected as the optimal solution scheme for the improved MPS method. The accuracy and feasibility of the present coupling model are validated through benchmark cases, such as dam break, wave motion, ice motion in regular waves and debris dam break flow. Furthermore, the simulation of the ship moving in the broken ice field is successfully conducted with the coupling model and the influence of ice-water coupling load on predicting broken ice resistance is also investigated.

Intelligent Predictive Networks for Cattaneo-Christov Heat and Mass Transfer Dissipated Williamson Fluid Through Double Stratification

This study aims to develop an efficient predictive model for Cattaneo-Christov heat and mass transformation of dissipative Williamson fluid with the effects of double stratification (CCHMT-DWF-DS) using the Levenberg-Marquardt Backpropagation (LMA-BP) algorithm. The under-consideration Williamson fluid flow is magneto-hydro-dynamic, incompressible and two-dimensional through a stretching sheet. The mathematical model of nonlinear partial differential equations for physical phenomena is transformed into ordinary differential equations by means of renowned similarity transformations. The solutions of physical problem are computed by bvp4c technique through MATLAB. The LMA-BP is employed to train a backward neural network capable of accurately predicting velocity, temperature, and concentration profiles under various physical conditions such as changes in the Hartmann number , Prandtl number , Schmidt number , Williamson parameter , the relaxation time of temperature , the relaxation time of concentration , temperature stratification , and concentration stratification for generating a variety of graphical outcomes and statistics. This research is significant for its innovative use of the LMA-BP in analyzing the complex dynamics of non-Newtonian fluids specifically the Williamson fluid, alongside the Cattaneo-Christov heat and mass flux model. The obtaining graphs have been discussed in detail. The thermal and solutal relaxation factors reduce heat and mass flow while fluid motion is delayed by the time-dependent parameter and further reduced by the Hartman number. The Cattaneo-Christov heat flux model enhances simulation accuracy by integrating temporal delays in heat transfer, proving beneficial for sophisticated industrial and scientific endeavors related to non-Newtonian fluids. This analysis offers a powerful predictive tool for applications in thermal management, industrial cooling systems, and biomedical fluid dynamics, advancing machine learning in fluid mechanics.

Numerical study of entropy production and EMHD effects in a peristaltic motion of Prandtl fluid with solid particles and porous medium

Particulate-fluid flow involving chemical reactions plays a crucial role in pharmaceutical manufacturing, catalytic converters, and combustion processes. This research focuses on the analysis of mass and thermal transfer, highlighting the influence of electroosmosis and magnetic forces on the flow of Prandtl fluid through a peristaltic porous micro-channel. In addition, the multiphase flow attitude, affected by chemical reactions, is extensively examined. The flow model is formulated by utilizing the lubrication theory estimation, integrating lengthy-wavelength and creeping flow approximation to simplify the considered problem. To further simplify the problem, Debye linearization is used, resulting in a set of two ordinary differential equations. The outcomes indicate that velocity drops with rising magnetic field, while it enhances with the Helmholtz-Smoluchowski velocity coefficient. Furthermore, thermal distribution increases with greater concentrations of solid fragments and greater magnetic field. These findings provide valuable insights into optimizing mass and thermal conveyance in peristaltic problems, with potential appliances spanning numerous industrial and biomedical areas.

Numerical Study of Local Scour and Hydrodynamic Pressure of Complex Bridge Piers

This study uses Computational Fluid Dynamics to investigate bridge foundations' scouring process and hydrodynamic pressure caused by an extreme flood. A Large Eddy Simulation model, compiled with a Navier-Stokes equations model, is used to compute the fluid motion with the Volume-of-Fluid to track the motion of the water surface. A Discontinuous Bi-viscosity rheological model describes the river's muddy bottom properties. The numerical results are further analyzed to understand the influence of exposed, closely spaced piles bridge on the scouring process. The results show that the extended foundation (with ten piles) has a maximum scour depth of approximately 10 m, which is 2.0 m greater than the non-extended foundation (with six piles). Specifically, the high velocity surrounding the exposed, tightly spaced piles may exacerbate the scouring problem. The design code suggests a hydrodynamic pressure of 10.9 kPa and 10.1 kPa for six and ten piles, respectively. The front-row piles' hydrodynamic loading is underestimated in the bridge design code. The maximum hydrodynamic pressure occurs at the front piles at roughly 1.8PI, where PI represents the hydrodynamic pressure. The velocity and hydrodynamic pressure at each pile are calculated, comparable with that in the bridge design code. This finding is important for the design of bridge foundations with exposed piles.

Analysis of ZnO-SAE50 Nanolubricant Performance under variable Thermal Conductivity and Solar Radiations: Model for Bidirectional Stretchable Surface

Analysis of thermal transport in nanolubricants is an interesting and potential topic. Hence, the current research focuses on the study of ZnO-SAE50 by adding the major effects of variable thermal conductivity, combined convection, and thermal radiations. The physical set up is designed for 3D dimensional flow through a surface and then investigated the results via numerical scheme. From detailed analysis of the physical results, it is examined that ZnO concentration and suction effects cause reduction in the fluid movement while for stretching case these variations are quite rapid than shrinking case. Further, the combined convective effects greatly influenced the fluid motion over the surface. The velocity increases rapidly under increasing Grashof effects and maximum motion is observed for stretching case. The temperature of ZnO-SAE50 enhanced due to increasing thermal radiations and ZnO concentration. However, minimal changes are investigated under variable thermal conductivity number , shterching/shrinking and maximum drop in the temperature is examined due to stronger Grashof number effects.

Sharp Cone-Broad Cone-Disk: Analytical Solutions in the Tunnel Mathematics Space to the Steady Navier-Stokes Equations in the Area of Boundary Layer for Incompressible Symmetric Flows Entrained by these Rotating Bodies

More than 150 years of history of efforts to solve the Navier-Stokes equation have clearly shown that, applying standard mathematical tools, it is possible to do this in only a small number of simple cases. Therefore, to solve such equations, we can try non-standard methods of mathematical modeling. In this case, the emphasis should be placed not on the mathematical accuracy of the proposed solutions, but on their correspondence to experimental data or solutions to the Navier-Stokes equations obtained by numerical methods. We believe that tunnel mathematics is such a method of mathematical modeling. Main theorem of tunnel mathematics allows us to reduce a system of the steady Navier-Stokes equations to simple ordinary differential equations that give solutions in planes parallel to the basic xy plane. Collecting such solutions, we finally obtain full 3D solution of a system of the steady Navier-Stokes equations. Approximate solutions for a system Sharp cone—Broad cone—Disk in the area of boundary layer can be obtained without use of specific software (including case of turbulent motion of fluid). We get solution for a rotating disk as a limit transition for a broad cone. If such solution will be similar with famous Karman`s solution for a rotating disk (we mean laminar flows), then we could conclude that our theory is successive.

Kernel Determination Problem in the Third Order 1D Moore-Gibson-Thompson Equation with Memory

In this study, we address the inverse problem of determining the convolution kernel function in the third-order Moore--Gibson--Thompson (MGT) equation, which is commonly used to model fluid motion with memory effects. Specifically, we focus on the determination of the unknown kernel, which governs the memory term in the equation. Initially, we employ the Fourier spectral method to solve the direct initial-boundary-value problem for a non-homogeneous MGT equation that with the memory term. The Fourier spectral method allows us to leverage the problem's inherent linearity and spatial homogeneity, leading to an efficient and explicit construction of the solution. The direct problem is analyzed under appropriate initial and boundary conditions, which are carefully specified to ensure mathematical consistency. To solve the inverse problem, we introduce an additional condition-typically a form of observational data such as at certain points-which provides the necessary constraints for determining the kernel. We prove local existence and uniqueness theorems for solution of the problem.

Enhanced energy efficiency by implementing MHD flow and heat transfer in Cu-Al2O3/H2O hybrid nanoparticles with variable viscosity

Hybrid nanofluids are engaged in phase-change materials and thermal energy storage systems to enhance heat transfer during the charging and discharging processes. Improved understanding of how variable viscosity and thermal radiation affect these fluids contributes to more efficient energy management. This study aims to formulate an efficient mathematical model for the two-dimensional flow of a hybrid nanofluid composed of copper (Cu) and alumina oxide (Al2O3) suspended with base fluid H2O to form a hybrid fluid under the influence of thermal radiation. The present study also integrates the effects of variable viscosity and viscous dissipation. Electromagnetic radiation impact due to temperature also amalgamated. The governing PDEs are reformulated into ODEs via tailored similarity transformations. These reformulated equations are then numerically resolved using Bvp4c solver, leveraging the shooting method within MATLAB for precision and efficiency. The most significant results are predetermined relevant parameters, such as the prosperity parameter, magnetic parameter, radiation parameter, slip velocity parameter,Biot number, convention parameter, Eckert number, heat source parameter, Prandtl number on velocity and temperature distribution are inspected graphically and in the form of table. Outcomes illustrate that fluid velocity flattens by increasing magnetic parameters because there exists a Lorentz force that opposes the fluid motion, whereas enhancement is noted via radiation parameter. Compared to conventional nanofluid, temperature curves of hybrid nanoliquid is higher. Furthermore, recent results indicate strong agreement for a specific instance.

Lie symmetry analysis on heat and mass transport aspects of rate type fluid flow with waste discharge concentration: Keller Box approach

The present analysis examines the effect of thermal radiation on the stream of Maxwell liquid past a stretchy surface in the presence of a zero-mass flux condition. The effect of waste discharge concentration, thermophoresis-Brownian motion, and porous media on the fluid motion is also considered. Investigation of the liquid flow with waste discharge concentration in stretched sheets may lead to the growth of effective methods for disposing of waste and preventing pollution. Due to their extensive applicability, the mechanisms of flow and heat transmission in the context of thermal radiation play a crucial role in research and industry. This phenomenon often occurs in spacecraft, nuclear reactor cooling, power production, aerospace technologies, combustion applications, gas turbines, hypersonic flights, and high-temperature processes. The modelled governing partial differential equations (PDEs) are converted into dimensionless ordinary differential equations (ODEs) utilizing appropriate similarity variables. Further, the Keller–Box approach is utilized to solve the resultant ODEs numerically. The influence of several parameters on the temperature, concentration and velocity profiles is shown via graphic representations. The intensification in Deborah’s number and porous parameter values declines the velocity profile. As the values of the radiation, thermophoresis, and Brownian motion parameters increase, the thermal profile increases. The concentration profile increases as the pollutant external source parameter value upsurges.

Rotating micropolar hybrid nanofluid: Exothermic/endothermic effects and waste discharge on exponential sheet

This research offers a comprehensive investigation into the steady‐state, three‐dimensional flow of an incompressible hybrid nanofluid over a bi‐directionally stretching exponential sheet. A central aspect of the study is the behavior of rotating micropolar fluids within a Darcy‐Forchheimer porous medium, enhanced by the inclusion of electromagnetic forces. The effects of embedding nanoparticles and in a water‐based fluid are explored to reveal their influence on fluid motion and heat transfer. The thermal dynamics are scrutinized, with particular emphasis on the roles of heat absorption and viscous dissipation. Moreover, this study incorporates both endothermic and exothermic reactions in radiative flows, alongside the impact of Soret and Dufour diffusion effects. The discharge of wastewater is a critical issue in environmental management and industrial applications, underscoring the need for rigorous regulation to prevent water pollution and ensure adherence to environmental standards. This research addresses the non‐Newtonian flow resulting from wastewater discharge, incorporating Arrhenius activation energy in the analysis. Furthermore, the behavior of microorganisms within the flow is studied under velocity slip conditions and a range of convective boundary conditions. Through the application of similarity transformations, the governing differential equations are derived and solved numerically using MATLAB's bvp4c solver, with results depicted through detailed graphical analysis to illustrate the fluid's complex behavior. The heat transfer rate gets reduced by 1.96% with the enhancement in the Eckert number.

An Eulerian Vortex Method on Flow Maps

We present an Eulerian vortex method based on the theory of flow maps to simulate the complex vortical motions of incompressible fluids. Central to our method is the novel incorporation of the flow-map transport equations for line elements , which, in combination with a bi-directional marching scheme for flow maps, enables the high-fidelity Eulerian advection of vorticity variables. The fundamental motivation is that, compared to impulse m , which has been recently bridged with flow maps to encouraging results, vorticity ω promises to be preferable for its numerical stability and physical interpretability. To realize the full potential of this novel formulation, we develop a new Poisson solving scheme for vorticity-to-velocity reconstruction that is both efficient and able to accurately handle the coupling near solid boundaries. We demonstrate the efficacy of our approach with a range of vortex simulation examples, including leapfrog vortices, vortex collisions, cavity flow, and the formation of complex vortical structures due to solid-fluid interactions.

Waves in Earth's core and geomagnetic field forecast

We use advanced numerical geodynamo series to derive a reduced stochastic model of the dynamics at the surface of Earth's core. Considering order 3 autoregressive (AR-3) processes allows to replicate the simulated spatiotemporal spectrum over a broad range of time-scales, spanning millennia to a fraction of year, including the cut-off found for periods shorter than approximately 2 years and associated with magnetic dissipation. We show how to derive such a forward model from a variety of input simulation series, and present its implementation into the pygeodyn data assimilation algorithm, based on a sequential ensemble method. The updated scheme is applied to perform magnetic field hindcasts and core flow reanalyses. For all observable length-scales, the rate of change of the observed magnetic field is most of the time accounted for within the spread of the forward model trajectories. AR-3 predictions on average supersede by about 35 % linear extrapolations on short (2 yr) time-scales, reducing high-frequency spurious variations in reanalysed flow motions. This improvement is reduced to ≈10% for 5 yr increments, with a large variability from one epoch to the other depending on the overall curvature of the magnetic field evolution. We perform a reanalysis over the period 1880–2023 covered by observatory and satellite records. We find enhanced kinetic energy in three period ranges around 12.5, 6.5 and 3.5 years. At all three periods, fluid motions share geometrical properties compatible with quasi-geostrophic magneto-Coriolis waves: equatorial symmetry, larger amplitude near the equator, flow dominated by low azimuthal wave number and modulated in longitude, phase speed much faster than the fluid velocity and decreasing with the period. At 6.5 yr period we trace back to the mid-1990's the patterns previously detected from satellite data. We also find in the 1960–70's a similar wave-train, possibly in link with the 1969 geomagnetic jerk. The AR-3 model, in conjunction with early satellite records, likely helps isolate such coherent features on interannual time-scales. Similar wave-like motions also show up at 3.5 yr period around 1970 and during the past decades. At periods around 12.5 yr we detect recurrent patterns starting as far back as 1920, and modulated over decadal time-scales. Our results show growing evidence for core dynamics governed by the presence of hydro-magnetic waves over a wide range of periods. This may allow deterministic and/or empirical descriptions of the signal that may help sound deep Earth's properties, and improve predictions of the magnetic field evolution.

Bubble Theory and its Applications in Underwater Explosion, Marine Cavitation, and Seismic Exploration

AbstractBubbles play crucial roles in various fields, including naval and ocean engineering, chemical engineering, and biochemical engineering. Numerous theoretical analyses, numerical simulations, and experimental studies have been conducted to reveal the mysteries of bubble motion and its mechanisms. These efforts have significantly advanced research in bubble dynamics, where theoretical study is an efficient method for bubble motion prediction. Since Lord Rayleigh introduced the theoretical model of single-bubble motion in incompressible fluid in 1917, theoretical studies have been pivotal in understanding bubble dynamics. This study provides a comprehensive review of the development and applicability of theoretical studies in bubble dynamics using typical theoretical bubble models across different periods as a focal point and an overview of bubble theory applications in underwater explosion, marine cavitation, and seismic exploration. This study aims to serve as a reference and catalyst for further advancements in theoretical analysis and practical applications of bubble theory across marine fields.

Computational role of homogeneous–heterogeneous chemical reactions and a mixed convective ternary hybrid nanofluid in a vertical porous microchannel

Abstract This article mainly scrutinizes the heat transfer and flow characteristics of a mixed convection ternary hybrid nanofluid in a porous microchannel considering the catalytic chemical reaction and nonuniform heat absorption/generation. Using appropriate similarity transformations, the modeled equations are converted into reduced ones and then solved via the Runge–Kutta–Fehlberg 4th/5th order method. To strengthen this analysis, the convection mechanism has been deployed. The effect of pertinent physical parameters on the fluid motion and thermal field is displayed, including some important engineering variables like the Nusselt number, Sherwood number, and drag force. The novel outcomes display that the flow reduces with porous permeability and nanoparticle volume fraction. The temperature of the nanofluid improves with nonuniform heat absorption/generation. The concentration decreases in the presence of both homogeneous and heterogeneous reaction intensities. The heat transfer rate enhances for the Eckert number, and a similar influence on the mass transfer rate is noticed for homogeneous reaction parameters. Further, the drag force declines for the Grashof number. The outcomes show that, in all cases, the ternary hybrid nanofluid shows a greater impact than the nanofluid. The attained findings represent applications in the era of cooling and heating systems, thermal engineering, and energy production.

Real-time volumetric imaging of cells and molecules in deep tissues with Takoyaki ultrasound.

Acoustic contrast agents and reporter genes play a critical role in allowing ultrasound to visualize blood flow, map molecules and track cellular function in opaque living organisms. However, existing ultrasound methods to image acoustic contrast agents predominantly focus on 2D planar imaging, while the biological phenomena of interest unfurl in three dimensions. Here, we introduce a method for efficient, dynamic imaging of contrast agents and reporter genes in 3D using multiplexed matrix array transducers. Our "Takoyaki" pulse sequence uses the simultaneous scanning of multiple focal points to excite contrast agents with sufficient acoustic pressure for nonlinear imaging while efficiently covering 3D space. Through in vitro experiments, we first show that the Takoyaki sequence produces highly sensitive volume images of gas vesicle contrast agents and compare its performance with alternative imaging schemes. We then establish its utility in cellular imaging in vivo by visualizing acoustic reporter gene-expressing tumors in a mouse model of glioblastoma. Finally, we demonstrate real-time volumetric imaging by tracking the dynamics of fluid motion in brain ventricles after intraventricular contrast injection. Takoyaki imaging enables a more comprehensive understanding of biological processes by providing spatiotemporal information in 3D within the constraints of accessible multiplexed matrix array systems.

Numerical Prediction of Two-Dimensional Coupled Galloping and Vortex-Induced Vibration of Square Cylinders Under Symmetric/Asymmetric Flow Orientations

This study presents an advanced numerical model for predicting a two-dimensional coupled galloping and vortex-induced vibration (VIV) in cross-flow and in-line directions of square cylinders under symmetric and asymmetric flow orientations. The present model combines the quasi-steady theory for the galloping with the nonlinear structure-wake oscillators simulating VIV, capturing the time-varying drag and lift hydrodynamic forces with the time-averaged and fluctuating components. By placing a flexibly mounted square cylinder in uniform flow at an initial angle of incidence, the cylinder is subject to instantaneous changes in the dynamic angle of attack accounting for relative flow-structure velocities. Modelling of such features in cross-flow and in-line directions for low and high mass ratio systems extends previous studies which have mostly focused on cross-flow responses of square cylinders with high mass ratios at a zero angle of incidence. New sets of empirical coefficients governing the drag and lift fluid forces for both the quasi-steady and wake oscillator approaches are introduced by calibrating with available experimental data in the literature, applicable to predict several flow-induced vibration phenomena under arbitrary flow-structure orientations. Mathematical criteria for the onset of two- and one-dimensional galloping instability are presented, verifying the likelihood of galloping occurrence. Parametric investigations are carried out to highlight the important effects of flow incidence angle, mass-damping ratio (Scruton number) and in-line response on the prediction of galloping and VIV in comparison with experimental results. By varying the reduced velocity parameter, the present model captures key qualitative features of the dominant galloping, interfering galloping-VIV and dominant VIV through the response amplitudes, mean drift displacements, oscillation frequencies, fluid force components and motion trajectories. Contributions from in-line responses are found to be meaningful for the interfering galloping-VIV system with a low mass-damping ratio and for an asymmetric flow orientation. The present model could be further calibrated and applied to other fluid-structure interaction applications with non-circular cross-sectional geometries under omnidirectional flow directions.

Side-heated Rayleigh–Bénard convection

Unlike in solids, heat transfer in fluids can be greatly enhanced due to the presence of convection. Under gravity, an unevenly distributed temperature field results in differences in buoyancy, driving fluid motion that is seen in Rayleigh–Bénard convection (RBC). In RBC, the overall heat flux is found to have a power-law dependence on the imposed temperature difference, with enhanced heat transfer much beyond thermal conduction. In a bounded domain of fluid such as a cube, how RBC responds to thermal perturbations from the vertical sidewall is not clear. Will sidewall heating or cooling modify flow circulation and heat transfer? We address these questions experimentally by adding heat to one side of the RBC. Through careful flow, temperature and heat flux measurements, the effects of adding side heating to RBC are examined and analysed, where a further enhancement of flow circulation and heat transfer is observed. Our results also point to a direct and simple control of the classical RBC system, allowing further manipulation and control of thermal convection through sidewall conditions.

Hydrodynamic Research of Marine Structures

Hydrodynamics plays a crucial role in the design and analysis of marine structures, as it involves the study of the motion of fluid and its interaction with various types of structures in a marine environment [...]

Dynamics of Viscous Jeffrey Fluid Flow Through Darcian Medium With Hall Current and Quadratic Buoyancy.

This contribution builds on existing studies by investigating the dynamics of Hall current in Jeffery fluid under radiative heat, convective boundary conditions, Joule heating, and Darcy dissipation. Hall current, an important phenomenon in engineering applications involving strong magnetic fields, highlights the impact of electromagnetic force in examining blood flow rate, determining charge drift velocity, density, and movement, and is used in power generators and high-voltage transformers. This analysis incorporates dissipative and thermal radiative heat and employs the effects of Hall current and Joule heating, resulting from porous medium resistance, to derive the partial differential equationsgoverning the dynamic systems. These equationsare then reduced to ordinary differential equations (ODEs) through similarity variables. The Galerkin weighted residual method (GWRM) is employed to examine the dynamics of Hall current and quadratic thermal buoyancy, shedding light on the thermal properties and hydrodynamics of Jeffrey fluid convection within a porous medium. The analysis reveals that in the presence of an applied magnetic field, the contribution of Hall current to flow and heat dynamics induces a magnetic force that enhances fluid motion and negatively impacts heat energy patterns. The imposition of dissipative heat physically increases the fluid temperature, owing to an increase in buoyancy current. The occurrence of thermal radiation, Hall current, viscous dissipation, and Joule heating can efficiently optimize the rate of heat transfer and shear stress. Moreover, the tabular results indicate that Jeffrey fluid, exhibiting higher relaxation time, will experience a lower friction coefficient and heat transferrate.

Hydrodynamic Fluidic Pump Empowered Sensitive Recognition and Active Transport of Hydrogen Peroxide in 1D Channels.

Through synthetic chemistry, the development of molecular devices for the precise selective recognition and active transport of small molecules stands as one of the most ambitious objectives in extensive medical, environmental, and biological applications. The periodical channels of the metal-organic frameworks (MOFs) with excellent chemical affinity offer vast regulatory space for reaching this goal. Herein, by post-modifying fluorescent probes and ionic liquid molecules into the Zr-MOFs (NU-1000), a donor-acceptor (D-A) system within the periodical 1D channels is created to construct a hydrodynamic fluidic pump within the abundant 1D channels. Irradiation with light serves to initiate and direct fluid motion, expediting the transport of H2O2 molecules to the active site, thus boosting the sensor sensitivity through gas enrichment. The rapid mass transfer, characterized by a high flow rate and intensified interaction between the D-A system and H2O2 molecules, enables the detection of H2O2 at concentrations as low as 20 ppb. Besides, with the aid of incident light, the pump system exhibits active transport characteristics by transporting radicals derived from H2O2 against a concentration gradient, reaching a remarkable 10th cycle. The strategy of achieving active transport of small molecules through pore modification holds promise for advancing the development of artificial bioactive channels.