Spatially damped continental shelf waves (CSWs) with diurnal tidal frequency outside Lofoten–Vesterålen in north-west Norway are studied theoretically for an idealized shelf topography. Wave damping is caused by the exchange of fluid on the shelf with an inner archipelago through a permeable coastline. This exchange is modelled by the application of a Robin condition at the coastal boundary. It is

Numerical simulations of flow-induced vibration on isolated and tandem elliptic cylinders with varying reduced velocities are carried out. Immersed boundary multi-relaxation-time lattice Boltzmann flux solver is used as numerical solution method so that the solution procedure can be conducted in a Cartesian grid. The accuracy and rationality of this method are verified by comparison with previous numerical

Slip flow in a rectangular cavity is studied. Using slip eigenfunctions, an exact series solution is found for a lid sliding longitudinally. For a transversely sliding lid, the stream function for Stokes flow is determined by a new set of slip eigenfunctions and supplemented by point match on the boundary. It is found that slip has considerable effect on the flow properties. Analyses of the region

Poisson equation lies in the heart of the numerical solutions of incompressible Navier–Stokes equations (NSEs) based on the popular projection methods, which decouple the pressure and velocities fields. This paper presents enhanced numerical solutions of the 2D incompressible NSEs inspired by a newly-developed Generalized Harmonic Polynomial Cell (GHPC) method for the Poisson equation, which has a

The present outbreak enables the researchers from fluid mechanics to widen the understanding of expelling respiratory liquids from a unique perspective to diminish the persistence of COVID-19. This article focuses on uncovering the instability mechanism responsible for forming droplets and aerosols during respiratory events such as breathing, talking, coughing and sneezing. We illustrate a mathematical

We study the linear stability of the Poiseuille flow of a viscoelastic upper convected Maxwell fluid in which the rheological parameters depend on the concentration of particles suspended in the fluid (dense suspension with negligible diffusion). After determining the basic flow and basic concentration profile we consider a temporal three dimensional perturbation in the form of a stream-wise and span-wise

Natural vortex development in double diffusive confined wall jet flow is firstly analyzed as a basic state. A consecutive vortices production and shedding processes are observed at moderated Reynolds numbers. The influence of these phenomena on combined transfers is then discussed. Strouhal number evolution was determined by spectral analysis conducted in the near-field region of the laminar wall jet

The behavior of an offshore structure in regular waves – and the related (linear and nonlinear) wave loads, added-mass and wave-damping coefficients, and body-motions – are commonly analyzed via the Green-function and boundary-integral method associated with potential-flow theory. This realistic, widely-used method requires accurate and efficient numerical evaluation of flows created by distributions

The Lattice Boltzmann Method (LBM) is promising for studies on Tsunami inundation. In this work, a Lattice Boltzmann Model for non-linear Shallow-Water Equations with a Turbulence Modeling​ (LABSWETM) was developed to consider the turbulence and non-Newtonian fluid behavior of tsunami flow. This involves incorporating the Sisko viscosity model into the lattice Boltzmann equation. By using the LABSWETM

We investigate by theoretical means the motion of a gravity current (GC) released from a lock into an ambient fluid in a horizontal channel of non-rectangular cross-section area (CSA) like triangle, trapezoid or semicircle. The lock contains an internal stratification, in particular a layer of density ρL overlain by a layer of density ρU, where ρo<ρU<ρL and ρo is the density of the ambient fluid. Assuming

The problem of the free streamline solutions of the Falkner–Skan equation is revisited in this paper. Until now, such solutions were found for negative values of the pressure gradient parameter β only. All of them are associated with slip velocities −1

Numerical calculations based on a recent version of the eddy-damped quasi-normal model (EDQNM-LMFA) are carried out for homogeneous isotropic turbulence (HIT) with the aim of investigating the dependency on the Reynolds number of second and third order velocity structure functions. The quantities investigated include the energy spectrum E, the non-linear energy transfer T as well as the second (S2)

This paper derives an averaged Lagrangian functional for dynamic coupling between rigid-body motion and its interior shallow-water sloshing in three-dimensional rotating and translating coordinates; with a time-dependent rotation vector. A new set of variational shallow-water equations (SWEs) and generalized Green–Naghdi equations for the interior fluid sloshing with 3-D rotation vector and translations

A test facility was built to investigate the cooling effects of a piezoelectric fan on a heated flat plate in a quiescent atmosphere. The facility consists of a heat source of a thin Ni-Cr foil and a piezoelectric fan for cooling the foil, where the surface temperature on the foil was measured by an IR camera. 3D unsteady numerical simulations were then conducted to analyze the relationship between

In this paper, we have considered a two-phase flow in a groovy curved channel. The fluid contains a uniformly distributed small particles and the flow is generated by a transient pressure gradient along the grooves. The governing equations describing the flow in the groovy curved domain are developed and the analytical solution of the complex flow field is determined using domain perturbation method

Exact and simple expressions for the permanent solutions corresponding to two oscillatory motions of incompressible upper-convected Maxwell fluids with exponential dependence of viscosity on the pressure between parallel plates have been established using suitable changes of the spatial variable and the unknown function and the Laplace transform technique. The solutions that have been obtained satisfy

Conjugate heat transfer analysis of supersonic turbulent flow over a finite thickness flat plate is studied numerically. The flow field is modeled by employing the Favre averaged Navier–Stokes (FANS) equations. Turbulence is modeled with the Menter’s shear-stress-transport (SST) k−ω model. The comparison of NCHT (non-conjugate heat transfer) and CHT (conjugate heat transfer) analysis shows that the

Compound droplets with different sizes are increasingly used in industrial production and academic research. This study aims to improve understanding of the dynamical behaviors of the compound droplet moving in microchannels. The compound droplet consisting of one inner core is initially concentric and placed at the entrance of a circular channel with a cone at the downstream region. Following this

The widespread use of available skin friction relations in engineering and in turbulence research is ample justification to examine their validities and limitations of use. The Prandtl–von Kármán logarithmic friction law (Prandtl, 1932) for instance, is vitally important for decades for predicting wall skin friction. There have been, however, rising concerns regarding its accuracy due to the deficit

Droplet impingement is a widespread phenomenon in nature and industrial production. Different from the problem of light drop/wall impact, which has been investigated early and sufficiently, few researches are found on the dynamic behavior and modeling of heavy drop impingement, which is widely existed in the field of plasma spray, 3D printing and ejecta mixing caused by detonation, etc. In this paper

Two-dimensional time-resolved particle image velocimetry (TR-PIV) measurements were carried out in confined and non-confined channels with a backward facing step (BFS) while the inlet flow was an oscillating jet from a double feedback fluidic oscillator. In addition, different Reynolds (Re) numbers in the range of 2500–10,000 were applied (based on the hydraulic diameter and mean velocity of jet throat)

When a high-velocity projectile penetrates a liquid-filled container, the projectile transmits its energy to the liquid through different ways; thus, different types of pressure waves can be generated in the liquid. In this study, an analytical model was established to calculate the drag pressure caused by two projectiles penetrating a liquid-filled container. The potential flow theory was used to

This paper presents the new version of the operational code used at the Tsunami Warning Centers in French Polynesia and in mainland France. This nested multigrid code solves either the nonlinear shallow water or the weakly nonlinear Boussinesq equations in a spherical or Cartesian coordinates system. The objective is to simulate the propagation of tsunamis both in the context of tsunami early warning

The steady rotational motion of a spherical particle with frictionally slip surface about a diameter in a quiescent unbounded fluid is studied analytically for a small but finite Reynolds number Re. The Navier–Stokes equation governing the axisymmetric fluid flow around the particle is solved by using a regular perturbation method. The expansion expression for the retarding torque exerted by the fluid

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

We propose an extension of the Ellipsoidal–Statistical BGK model to account for discrete levels of vibrational energy in a rarefied polyatomic gas. This model satisfies an H-theorem and contains parameters that allow to fit almost arbitrary values for the Prandtl number and the relaxation times of rotational and vibrational energies. With the reduced distribution technique, this model can be reduced

The aerodynamic noise generated from a cooling fan and its support frame is one of the major noise sources of many engineering machines, such as automobile engines and communication base-stations. A generic model composed of a vertically-installed flat strut behind an asymmetrical airfoil is used to investigate numerically the noise characteristics and generation mechanism of a cooling fan by using

With increasing application of technologies related to electric field being used to enhance heat transfer, it is important to understand better the effects of electric field and lateral advection on the thermal field. In this work, we present a detailed study of the linear dynamics of the flows subjected to simultaneously a thermal field and an electric field (which we call electro–thermo–hydrodynamic

The exact spheroidal-function series solution for the time-harmonic acoustic scattering of a plane wave by two fluid confocal prolate spheroids is developed and a numerical implementation is formulated and validated by independent methods. The two spheroids define three regions in which the acoustic fields are expanded in terms of spheroidal wave functions multiplied by unknown coefficients. These

To better understand the complex flow in arteries it is necessary to analyze the fluid–structure interaction between the time dependent velocity field, the non-Newtonian fluid, and the elastic blood vessels and to investigate the wall-shear stress distribution that develops in the elastic vessel during an oscillation cycle. The scope of this study is to quantify the influence of the viscoelastic fluid

Capacitance sensor is a non-intrusive devices used for the void fraction measurement in two-phase flows. Capacitance sensor is formed by two electrodes placed at the outside walls of a dielectric pipe, through which a two-phase medium flows. The capacitance of the sensor depends on the geometric arrangement of electrodes and distribution of the electrical field, which depends on the electrical permittivity

In this paper, a theoretical model is developed to describe the cerebrospinal fluid (CSF) flow in the subarachnoid space as the head is exposed to sudden external impacts. Although extensive study has been performed, there is a lack of understanding of the transient CSF flow and its critical role in the concussion process. The problem involves a solid object, i.e. brain matter, bathed in a liquid environment

The unstable behavior of the compressible Gaussian-type vortex transported by a uniform flow is investigated using the 16th-order high resolution multioperators-based scheme for the Euler equations. The onset and two stages (linear and non-linear) of the instability process calculated without any artificial exciter are described. It is shown how the most unstable mode comes into being from chaotic

New expressions are derived for the Green function (GF) for diffraction and radiation of waves by a two-dimensional (2D) body in finite water depth. The finite depth GF is expressed as a sum of singularities, the infinite depth GF and smoothly-varying integrals that are convergent for all parameter values. The infinite depth component is given explicitly, making it very fast to compute. Explicit expressions

The flow past a circular cylinder constrained under large blockage exhibits features even in the steady regime, that strikingly contrast those corresponding to its unbounded counterpart. While several studies are dedicated towards understanding this classical flow problem in unbounded medium, surprisingly, very little efforts have been put forward to extract details of flow alterations in a highly

The log-normal type of turbulence energy spectral function, derived from the maximum entropy principle, is shown to be parameterizable in terms of root turbulence variables including the Reynolds number. The spectral function is first compared with a number of experimental data sets, showing a very close agreement across the entire energy and length (wavenumber) scales. The peak wavenumber (m) and

This paper presents a global stability analysis of the boundary layer developed on a slender circular cone. The base flow direction 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 semi-cone

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

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

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 are different from those 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

In this paper, the propulsion performance of a bio-inspired underwater robot with a pair of ray-supported undulating pectoral fins is numerically investigated with a fully coupled fluid–structure interaction model. In this model, the flexible fin rays are represented by nonlinear Euler–Bernoulli beams while the surrounding flow is simulated via solving the Navier–Stokes equations. Kinematically, each

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 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

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