A fast numerical scheme is proposed to determine the velocity field of an incompressible fluid in a concentric annulus under a constant pressure gradient. The idea behind the scheme is to find the radius R in the annulus where the shear stress becomes zero. In the region from the inner wall at R=κ to R, the shear rate is positive, while it is negative from this radius to the outer wall at r=1. Integrating

We extend a method developed by Fusi and Farina (Appl. Math. Comp. 320, 1-15, 2018) to obtain semi-analytical lubrication-approximation solutions for the flow of a Bingham-plastic in a tube of variable radius. The proposed method is applicable provided that the unyielded core extends continuously from the inlet to the outlet. It turns out that the variable radius of the latter core obeys a stiff integral-algebraic

Uncured styrene-butadiene rubber (SBR) can be modelled as a viscoelastic material with at least two different relaxation mechanisms. In this paper we compare multi-mode constitutive models combining two viscoelastic modes (linear and/or nonlinear) in three possible ways. Our particular choice of the two modes was inspired by models originally developed to describe the response of asphalt binders. We

We investigate the linear stability characteristics of a pressure-driven two-layer channel flow of immiscible Newtonian and Herschel-Bulkley fluids subjected to an applied electric field normal to the flow. The linear stability equations are derived and solved using an accurate spectral Chebyshev collocation method. It is found that the electric field can stabilise or destabilise the flow depending

We derive a simple procedure for solving systems of linear equations arising from the linearization of the VTN-phase stability problem. Using the structure of the Hessian matrix, the solution is obtained by sequential usage of the Sherman-Morrison formula. The great advantage of the method is that the system of equation can be solved without even assembling the system. The performance and the speed-up

In a recent article entitled “Solubility Parameter of Carbon Dioxide–an Enigma” [1], Marcus reported the literature values for the solubility parameter of liquid carbon dioxide (CO2) at 298 K with discrepancies as large as 200%. An analogous article on ionic liquids has also been published [2], entitled: “Chameleonic Behavior of Ionic Liquids and Its Impact on the Estimation of Solubility Parameter”

In this study, the isothermal binary vapour-liquid equilibrium (VLE) data for the butan-1-ol + butane-1,4-diol/butane-2,3-diol system was measured and modelled, for use in the design and rating of separation processes. P-T-x-y equilibrium measurements were performed at four temperatures from approximately 353–388 K. A dynamic-analytical apparatus was utilized to perform the measurements at sub-atmospheric

Droplets impacting on superhydrophobic surfaces with submillimetric or millimetric macrotextures can rebound completely after a short contact time, which is of practical importance in applications like self-cleaning and anti-icing. Many researches have been done on the centered impact, but the off-centered impact is rarely studied, even though it occurs more often. In the present work, we investigate

Sloshing refers to the motion of the free liquid/gas interface inside a partially filled container subjected to an external excitation with a consequent motion of the system center of gravity. Several parameters related to the fluid container, the fluid properties, the excitation levels, and the gravitational environment govern this phenomenon. Moreover, it is a significant cause of disturbance in

The effect of drag reducing riblets on the flow structure was examined experimentally for a turbulent boundary layer at Reθ = 9890 and riblet spacing s+ = 13.4. Trapezoidal riblets were used, which were attached to the water tunnel wall as a coating. Force measurements were performed to quantify the amount of drag reduction. Then, the mechanism underlying this reduction was investigated by stereo-PIV

Two phase flow is of great interest in chemical and petroleum industries, and multiphase pipe flow models with closure relationships require experimental data for their development and validation. However, only little experimental information is available for slightly upward inclined pipes. Experimental investigations of single elongated bubble in marginally upwardly inclined pipes less than 10° have

This paper describes an experiment conducted to investigate thermal distribution during liquid atomization. An infrared camera was used to measure liquid temperature changes over time during atomization. Effects of device frequency, input power, and liquid viscosity on thermal distribution during surface acoustic wave (SAW) atomization were investigated, both experimentally and through simulation.

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 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

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

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

In this paper, we present exact Riemann solvers for the Riemann problem and the half Riemann problem, respectively, for one‐dimensional multi‐material elastic‐plastic flows with the Mie‐Grüneisen equation of state(EOS), hypo‐elastic constitutive model and the von Mises' yielding condition. We firstly analyze the Jacobian matrices in the elastic and plastic states, and then build the relations of different

In recent years, multilayered hierarchical compositions of the well-known and widely used Gaussian process models called deep Gaussian processes are finding use in the approximation of black-box functions. In this paper, the performance of deep Gaussian process models is empirically evaluated and compared against the well-established Gaussian process models with a special emphasis on engineering problems

This paper uses gradient-based optimization to minimize the mass of a solar-regenerative high-altitude long-endurance flying-wing aircraft while accounting for nonlinear aeroelastic effects. The aircraft is designed to fly year round at 35° latitude at 18 km above sea level and subjected to energy capture, energy storage, material failure, local buckling, stall, longitudinal stability, and coupled

Chemical flooding has been implemented intensively for some years to enhance sweep efficiency in porous media. Low salinity water flooding (LSWF) is one such method that has become increasingly attractive. Historically, analytical solutions were developed for the flow equations for water flooding conditions, particularly for non-communicating strata. We extend these to chemical flooding, more generally

This paper demonstrates the development of purely data-driven, nonintrusive parametric reduced-order models for the emulation of high-dimensional field outputs using randomized linear algebra techniques. Typically, low-dimensional representations are built using the proper orthogonal decomposition combined with interpolation/regression in the latent space via supervised learning. However, even moderately

Thermal residual stresses can have a substantial impact on the bond-line fatigue of wind-turbine blades and the initiation of tunneling cracks in the adhesive layer early in their operational life. Thermal residual stresses develop during the manufacture of the blade as a consequence of the temperature difference between the curing conditions and the operating environmental conditions. Polymers are

In this paper, the interactions between extreme waves and a vertical cylinder are investigated through a 3-D two-phase flow model. The numerical model is verified and validated by experimental data. Then, two factors are considered, the global wave steepness and the frequency bandwidth of the wave groups, in the studies of the in-line wave forces and the wave run-up around a cylinder. It is found that

In support of NASA’s Triton Hopper project, mechanical response data for solid nitrogen are needed for concept validation and development. Available mechanical properties data is sparse with only three known indentation measurements existing between 30 and 40 K. To generate more data, a custom instrumented hardness tester was developed to interface with a cryostat. The system was used to conduct cylindrical

This paper reviews the literature published since 1994 related to the behaviour of composite materials at low and cryogenic temperatures. The material properties addressed are: tensile, compressive and shear strength, elastic modulus and stress-strain behaviour; mechanical and thermal fatigue response; fracture toughness; impact resistance; thermal expansion and thermal conductivity; tribology and

In the suspension high velocity oxy fuel (SHVOF) thermal spray, a suspension is injected into the combustion chamber where the jet undergoes primary and secondary breakup. Current knowledge of the primary breakup within the combustion chamber is very limited as experimental investigations are impeded due to direct observational inaccessibility. Numerical methods are also limited due to the computational

The evolution of interfacial waves is investigated for a stratified laminar-laminar flow in a plane channel using numerical simulations based on the Volume of Fluid (VOF) method. Different nonlinear instability mechanisms that can promote saturation or rapid amplification of interfacial waves are investigated. Controlled disturbances are introduced at the interface between the two fluids, to assess

The experiments of co-current vertical upstream air-water two-phase flow in a 66 mm × 66 mm square channel were carried out. The superficial liquid velocity ranges from 0.765 m/s to 1.53 m/s and the superficial gas velocity ranges from 0.0215 m/s to 0.313 m/s, including bubbly flow and cap-bubbly flow. A dual wire-mesh sensors (WMSs) was used to measure the bubbles in the two-phase flow. The local

Purpose This study aim to use the finite volume method to solve differential equations related to three-dimensional simulation of a solar collector. Modeling is done using ANSYS-fluent software program. The investigation is done for a photovoltaic (PV) solar cell, with the dimension of 394 × 84 mm2, which is the aluminum type and receives the constant heat flux of 800 W.m−2. Water is also used as the

The study aimed to enhance the heat transport by improving the hydrodynamic structure of the system by changing and restructuring the duct's internal geometry. Modern fins, of the shape ‘V’, have been proposed with different dimensions, and they are periodically arranged over the duct surfaces. The most important steps of this research are the change in the V-fin attack-angle (40°–80°), length (H b/2

The relative wall-normal displacement of the origin perceived by different components of near-wall turbulence is known to produce a change in drag. This effect is produced for instance by drag-reducing surfaces of small texture-size like riblets and superhydrophobic surfaces. To facilitate the research on how these displacements alter near-wall turbulence, this paper studies different strategies to

The rheological behaviors of a compound droplet in a confined geometry are of importance in many industrial and natural processes. However, a detailed numerical simulation of the finite deformation and its transition to the breakup of the multi-core compound droplet in an axisymmetric T-junction channel is still lacking. The present study is to fill this gap through the numerical simulations of a two-core