We present convective instability analyses of the boundary-layer flows originated over cones (with half-angle ψ≤90∘) rotating in an otherwise still conducting fluid. A uniform magnetic field (with magnetic strength parameter, m≥0) is acting normally on the surface of each cone. In the non-magnetic case of cones, comparison of present results with existing experimental and theoretical studies lead *to

Wind load prediction is critical to the design of buildings, especially skyscrapers, because wind-induced dynamic loads and vibrations can often be a major concern that dominates the design. This paper presents a real-time wind load predictor for buildings by training an artificial neural network, with big data generated from a well-established software package for computational fluid dynamics (CFD)

The complexity of the formation mechanism of ventilated cavities makes it difficult to be explored experimentally. In this study, the formation mechanism of cavity regimes around a gas jet cavitator were first numerically predicted using the partially averaged Navier–Stokes (PANS) and homogeneous free surface models. The numerical framework was validated by comparing the numerical predictions with

The major goal of this article is to analysis a mathematical model of a non-classical one-dimensional moving boundary problem in the presence of convection effect when one surface subjected to the most generalized boundary conditions. The control function describes the cooling and heating effect depends on the evolution of heat flux at x=0. The thermo-physical properties are assumed to be constant

The development of Marine Renewable Energy based on tidal currents at a selected area needs to first analyze the flow characteristics and thus the bathymetry induced turbulence in this area. The present study aims to investigate turbulence characteristics around two wall mounted obstacles in tandem, which represent seabed obstacles in a high Reynolds number flow. 2D planar PIV measurements are performed

This paper presents a global stability analysis of the boundary layer developed on a slender circular cone. The direction of the base flow is towards the apex of a cone, and the pressure gradient is positive (adverse) in the flow direction. The decelerating base flow is non-parallel and non-similar. The increased semi-cone angle increases the adverse pressure gradient in the flow direction. For a given

Janus spheres are heterogeneous amphiphilic particles having partially slippery and partially sticky surface. As a result, hydrodynamic forces such as drag and lift on a Janus sphere is different from that on a homogeneous sphere. Several applications of Janus particles require high particle concentration in a continuous fluid medium making the interactions between them inevitable. Therefore, in this

In the paper, we first present an exact solution for geophysical internal waves with centripetal forces and geophysical edge waves without centripetal forces in modified equatorial β-plane approximation. Then we apply the short-wavelength perturbation method to show an instability threshold for geophysical internal waves propagating eastward with centripetal forces and geophysical edge waves without

The phenomenon of calcium alginate gel formation from sodium alginate drop impact on calcium chloride liquid pool generates enormous scientific interest. The present work features on the investigation of interfacial heat transfer during sodium alginate drop impact on a heated calcium chloride liquid pool. The liquid pool has been heated at different temperatures varying from 20 °C to 70 °C. The drop

We investigate the axisymmetric slow viscous liquid flow around a spherical bubble located on the axis of a long circular tube analytically based on the Stokes approximation. The bubble translates along the axis of the tube with a constant velocity within Hagen–Poiseuille flow flowing far from the bubble. The translating velocity of the bubble and mean velocity of the Hagen–Poiseuille flow are given

The flow induced by a simultaneously rotating and radially stretching disk is revisited in this paper. The steady solution is given by a power-series of exponentials including the governing parameter of the problem c=Ω∕s, which is the ratio of the angular velocity of rotation Ω and the strain rate of stretching s . Since the series satisfy the far field conditions automatically, the boundary value

Hyper-singular integral equations are often applied in the frequency-domain wave diffraction/radiation analyses of marine structures with thin plates or shell sub-structures. Their numerical solutions require the higher-order derivatives of the free-surface Green function featuring hyper-singularity, and hence the corresponding evaluation is very challenging. To circumvent the associated numerical

Consider the propagation of a gravity current (GC) sustained by a source of a fluid of density ρc and constant volume rate Q into an ambient fluid of height H and density ρa over a permeable bed. The porous layer of a given length Δxp is located at the bottom of the container. Assume Boussinesq and large Reynolds-number flow. We present a new model for the prediction of the thickness h and depth-averaged

This paper presents a detailed investigation on the flow characteristics and the bed-shear-stress distribution around a finite circular cylinder at a fixed Reynolds number (Re = 2 ×104) and seven aspect ratios (AR = 0.5∼6) by solving the Reynolds Averaged Navier–Stokes (RANS) equations. It is found that, for a moderate Reynolds number and a relatively large boundary-layer thickness, the time-averaged

This work presents the numerical modeling of a sliding droplet on a vertical smooth wall under hydrophobic and hydrophilic conditions using the multiphase Shan–Chen Lattice Boltzmann Model (SC-LBM). The gravitational action above the interfacial force was introduced through the variation of the Bond number and contact angle between droplet, solid surface and surrounding fluid. A critical Bond number

A 2D numerical wave tank based on the fully nonlinear potential flow theory is built to simulate the water resonance between two fixed rectangular barges, focusing on the influence of the gap width and incident wave steepness on the liquid motion and hydrodynamic forces on the surrounding bodies. The initial boundary value problem (IBVP) for disturbed velocity potential is solved through boundary element

A semi-analytical study of the steady flow around a spherical particle rotating in an incompressible Newtonian fluid inside an eccentric spherical cavity with slip surfaces about their common diameter is presented at low Reynolds numbers. To solve the Stokes equation, a solution consisting of the general solutions in two systems of spherical coordinates is employed and the boundary conditions are fulfilled

In this paper, we present a general framework to construct section-averaged models when the flow is constrained – e.g. by topography – to be almost one-dimensional. These models are consistent with the two-dimensional shallow water equations. After rewriting the two-dimensional shallow water equations in a suitable set of coordinates allowing to take care of a meandering configuration, we consider

Different authors have studied incompressible fluid flow through two inclined planes. Previous authors have used different numerical methods to find the velocity profile of fluid flow for Jeffery–Hamel problem, which is known as the forward problem. It may be interesting to study the inverse problems related to the above. In that case, the velocity profile may be known and then the angle between two

Due to the importance of the usage of nano-technology based fluids in several industrial processes, the presented research deals with mathematical modeling of a comb-drive MEMS-based sensor for determinations of the physical properties of nanofluids. The proposed sensor is made up of a driving comb, sensing comb, and a sensing plate. It is actuated longitudinally via the electrostatic force created

The present study investigates the vortex dynamics of the rectangular shaped synthetic jet and reports the occurrence of vortex ring bifurcation along with other reported modes such as axial switching and the vortex suction. The novel finding of vortex ring bifurcation of rectangular synthetic jets has been observed without any other mode of excitation except the periodic axial actuation. The experiments

To rapidly and accurately identify the characteristics of the distributed force and reconstruct the force field on tube bundles in a cross flow, modal decomposition methods for a three-dimensional turbulent flow are studied. This is done with proper orthogonal decomposition (POD), dynamic mode decomposition (DMD), and the regularization method for DMD. A 3-D turbulent cross flow computational fluid

The Floquet theory is combined with the unsteady Orr–Sommerfeld equations for the first time to model the linear stability of a fluid mud–water interface under the influence of a linear long travelling wave (or linear shallow water wave). The modelling results reveal three instability modes that could appear on the fluid mud–water surface: the Kelvin–Helmholtz (K–H) and finite-wavelength (F-W) instabilities

The normal impingement of axisymmetric Homann stagnation-point flow on a surface executing perpendicular, planar, biaxial stretching is studied. The flow field generated is an exact solution of the steady, three-dimensional Navier–Stokes equations in the form of a similarity solution. It is shown that two sets of dual solutions exist, forming four different branches of steady solutions. For sufficiently

As long waves propagate over an island, wave energy can be trapped in the shallow water near the coastline due to the effect of refraction and diffraction. However, in some particular situations extremely huge near-shore waves can be excited due to the resonance of edge waves. This study focuses on the occurrence condition of the resonance phenomenon, and mainly investigates the effects of geometric

Acoustic streaming effects can play an important role for promoting heat and mass transfer. Considering the viscous loss inside the viscous boundary layer on the particles surface, a numerical model for the acoustic streaming outside a two-dimensional spherical particle in a plane standing wave sound field is established, and the distribution characteristics of the acoustic streaming outside the particles

Nanofluids are of immense importance to the researchers as they have significant uses industrially due to their high heat transfer rates. This new model is employed to examine the electroosmotic flow of magnetohydrodynamic nanofluids through an asymmetric microfluidic channel. Microchannel flow is driven by the electroosmosis and peristalsis mechanisms. Nanoparticles (copper, alumina and titania) with

Experimental tests for characterizing bubble breakage dynamics in different locations of a stirred tank with a 6-bladed impeller were carried out for a range of impeller Reynolds number (Re) using water as a continuous phase. The dynamic behavior of the bubble from the injection point until arriving at the impeller region was studied by using a high speed imaging method. The deformation behavior, local

The effects of jet pulsation intensity and excitation Strouhal number on the flow and dispersion characteristics of dual parallel plane jets at a low Reynolds number of 200 were experimentally studied so that the transition from laminar to turbulence was focused. A hot-wire anemometer was used to record the jet velocities. The flow patterns were obtained using the laser-light sheet assisted smoke flow

In this paper, the interaction between two initially circular in-line bubbles during their rise in a viscoelastic liquid under gravity is numerically simulated by weakly compressible smoothed particle hydrodynamics (WC-SPH). The background fluid is assumed to obey Oldroyd-B rheological model and the surface tension between two phases is evaluated by continuum surface tension (CST) method. First, it

A lid-driven cavity flow of kaolinite suspension is investigated using a numerical approach. The suspension with a kaolinite concentration in the range of 15–28.5wt% is modeled using Bingham–Papanastasiou approach. The cavity is of a rectangular shape and has different aspect (height-to-width) ratios, that is, 0.5 (shallow cavity), 1 (square cavity), and 2 (deep cavity). The width-based Reynolds number

According to Kelvin, a point pressure source uniformly traveling over the surface of deep calm water leaves behind universal wake pattern confined within 39° sector and consisting of the so-called transverse and diverging wavefronts. Actual ship wakes differ in their appearance from both each other and Kelvin’s prediction. The difference can be attributed to a deviation from the point source limit

It is shown that a large class of rotating disks flows described by an exact solution of the Navier–Stokes equations can be mapped on the mechanical motion of a point mass in the complex domain. The mathematical procedure, the physical features and the advantages of the point-mechanical approach are presented for von Kármán’s classical swirling flow and its magneto-hydrodynamic counterpart in detail

George Santayana’s aphorism “Those who cannot remember the past are condemned to repeat it” has never been more apposite than as applied to this paper. The paper rebutted here reproduces, without any form of acknowledgement, the method of reproducing characteristics of the atmospheric boundary layer (ABL) in a wind tunnel published in 1957 (Owen and Zienkiewicz, 1957). This method, together with the

To identify laminar/turbulent transition paths in plane Couette flow, a variational formulation incorporating a restricted nonlinear (RNL) system that retains a single streamwise Fourier mode, is used. Considering the flow geometry originally used by Monokrousos et al. (2011) and Duguet et al. (2013) and the same Reynolds numbers (Re), we show that initial perturbations obtained by RNL optimizations

The Lattice Boltzmann Method (LBM) was implemented to simulate the two-dimensional (2-D) Rayleigh–Taylor instability (RTI) during the mixing of the immiscible fluids. Two important parameters of the density and the viscosity as represented respectively by the Atwood and the Reynolds numbers were considered. In the calculation the density of two immiscible fluids was calculated by using the equation

Speckle images have found multiple applications in image-based measurement techniques, where the objective of measurement is the estimation of speckle displacements between two often consecutive images. Depending on the characteristics of a measurement system and its measurands, the signal-to-noise ratio (SNR) of recorded images may become low and even marginal. One solution to improve the accuracy

A kinetic-theory based approach known as the lattice Boltzmann method (LBM) with multiple-relaxation-time (MRT) collision is employed to assess the non-Newtonian fluid models for standard two-dimensional benchmarks flow configurations. A two-dimensional nine-velocity square lattice (D2Q9) is used as a basic space-microscopic-velocity coupled LBM structure. The MRT-LBM formulation for the non-Newtonian

Bioinspired grooved surface structure design has been widely used as an efficient passive flow control method in drag reduction. The total drag of plate with grooved surface structure can be decomposed into friction and pressure drag. In this paper, the relationship between them and the distribution of vortex structure in flow field has been analyzed for obtaining the drag reduction mechanism of grooved

Submerged gas jet is commonly encountered in underwater cutting, underwater jet-propulsion, liquid metal mixing and other applications. In this paper the transient dynamics for the high-speed submerged gas jet in a flowing water environment was investigated. The experiments were carried out in an open water tunnel which could achieve high degassing rate. The jetting flow rate was varied from subsonic

Rayleigh–Taylor instability (RTI) is a common phenomenon in daily life and in industrial application. Despite the long history of investigating the RTI with periodic boundary condition, there are only few studies for the RTI with no-slip side wall boundary condition. In fact, the RTI with the side wall boundary condition is more realistic physics. In this work, we investigate the side wall boundary

The present paper investigates numerically the hydrodynamic instabilities occurring in a cylindrical container filled with a conducting viscous fluid and submitted to an axial magnetic field. The axisymmetric swirling flow produced by rotation of the bottom disk, in which a vortex breakdown bubble occurred on the axis of symmetry. This flow structure represents one of the most important instabilities

Turbulence modeling plays a crucial role in simulating unsteady characteristics of cavitation flows. Owing to the different theoretical backgrounds of partially averaged Navier–Stokes (PANS) and filter-based models (FBMs), the differences in their unsteady cavitation flow predictions are worth comparing. In this study, PANS and FBM were used to predict the cloud cavitation regime around a three-dimensional

The near-field flow characteristics and jet fluid dispersion properties of non-oscillating and transversely oscillating jets issued from a fluidic oscillator were studied experimentally. A V-shaped fluidic oscillator was designed to induce transverse jet oscillations by merging two bifurcated alternatively issuing side jets. The characteristic flow patterns, evolution processes, velocities, vorticities

The wake dynamics behind a sinusoidally pitching custom designed symmetrical airfoil is analyzed computationally. The effect of pitching frequency and pitching amplitude is investigated independently at a constant Reynolds number. The wake patterns are found to exhibit a transition from von Karman to reverse von Karman vortex street and from symmetric reverse von Karman vortex street to asymmetric

This work focuses on the study of the phenomenon of vortex-induced vibrations in overhead lines under the effect of weak winds. Full three-dimensional simulation is not feasible because of the high length to width aspect ratios of the overhead lines. Thus a quasi-3D method based on strip theory is adopted in this work. This method decouples the system of interactions between the overhead line and the

The problem of an axisymmetric translational motion of an incompressible microstretch fluid past an immiscible stationary microstretch droplet in the presence of a uniform magnetic field is investigated. The inertial terms in the equations of motion are neglected, therefore the microstretch scalar function is uncoupled from the stream function and microrotation component. Analytical solutions are obtained

Thermal characteristics of time-periodic electroosmotic flow are analyzed in a micro-annulus under the influence of various alternating electric fields. Representative hydrodynamic and thermal quantities, i.e. volumetric flow rate and Nusselt number, demonstrate oscillatory behaviors approaching a quasi-steady state if few periods of time elapse. An important parameter named dimensionless frequency

The present paper is an extension of the work done by Fang and Tao (2012) in the presence of a magnetic field. The external magnetic field is applied normal to a stretchable disk surface and heat is transferred from the disk surface to the ambient fluid which gives a new family of unsteady viscous flow over a stretchable rotating disk with deceleration. The Navier–Stokes equations and the energy equation

Viscous/inviscid interaction methods employing velocity decomposition have been explored for reducing computational costs in external flow problems. For this, viscous simulations are made in reduced computational domains encompassing the rotational flow region. The coupling of potential and viscous solutions is made on a boundary of negligible vorticity, assessed by means of sampling lines normal to

The motion of the solid particles in the enclosed cavity is important, to investigate the interaction between the motion of the solid particles and the fluid flow, the motion of a neutrally buoyant elliptical particle in a lid-driven square cavity is studied with the lattice Boltzmann method. To understand, predict and control the motion of the elliptical particle, the effects of the aspect ratio,

Vortex-induced vibration (VIV) of an elastically supported disk is investigated computationally using large-eddy-simulation (LES). The disk motion is constrained to move in the transverse plane vertical to the free stream. Two sets of simulations are conducted at Re=165 and 210 over the reduced velocity range 3≤UR≤7.5 respectively. The disk shows a highly periodic large-amplitude vortex-induced vibration

This work endeavours to study the problem of axisymmetric oblique stagnation point flow above a rotating disc. An external flow impinges obliquely on a disc when the disc is rotating with constant angular velocity. Suitable similarity variables are introduced, for the first time, to transform the governing Navier–Stokes equations into a highly nonlinear system of ordinary differential equations, governed

The applications of freely falling bodies in steady water or air have been widely observed in nature, from the dispersing of a tree seed to the re-entry of a space shuttle. Disparate objects exhibit particular falling styles which have been studied for a long time. However, the mechanism behind this extensive phenomenon has not been clearly understood. In this paper, we investigate experimentally the

In this paper, we study the stability of a barotropic polar vortex cap on a rotating sphere. We present the linear stability analysis of the polar vortex cap, approximating the piecewise-continuous vorticity distribution by zonal bands of uniform vorticity. We investigate the dependence of the flow stability on the location of the vortex cap, modes of perturbation and rotation speed. The linear stability

A deformity of magnetic field discloses that different particle of ferrofluid exhibits different pattern to accumulate more closely with strong magnetic properties; this is because of the existence of a homogeneous ferromagnetic liquid. In this context, the Newtonian fluid (ordinary liquid) is magnetized by dispersing into porous media. A mathematical model for ferromagnetic fluid is developed by means

The swimming of a deformable uniform sphere is studied in second order perturbation theory in the amplitude of the stroke. The effect of the first order reaction force on the first order center of mass velocity is calculated in linear response theory by use of Newton’s equation of motion. The response is characterized by a dipolar admittance, which is shown to be proportional to the translational admittance

The laminar–turbulence transition phenomenon widely exists on the surface of many energy equipment, which is deserved to be studied because of the complex mechanics and some induced undesirable consequences. The goal of present work is to investigate the transitional flows around the forward and reversed hydrofoils at different incidences using the SST γ-Re˜θt transition model, with special emphasis