Stefan blowing, navier slip and radiation effects on thermo-solutal convection from a spinning cone in an anisotropic porous medium

Thermal radiation features in many high temperature materials processing operations. To evaluate the influence of radiative flux on spin coating systems, we consider herein the thermo-solutal (coupled heat and mass transfer) in steady laminar boundary layer natural convection flow from a rotating permeable vertical cone to an anisotropic Darcian porous medium. Surface slip effects are also included in the model presented. The conservation equations are rendered into self-similar form and solved as an ordinary differential two-point boundary value problem with surface and free stream boundary conditions using MAPLE 17 software. The transport phenomena are observed to be controlled by ten parameters, viz primary and secondary Darcy numbers (Dax and Da), rotational (spin) parameter (NR), velocity slip parameter (a), suction/injection parameter (S), thermal slip parameter (b), mass slip parameter (c) buoyancy ratio parameter (N), and conduction-radiation parameter (Rc). Tangential velocity and temperature are observed to be enhanced with greater momentum slip whereas swirl velocity and concentration are reduced. Increasing swirl Darcy number strongly accelerates both the tangential and swirl flow and also heats the regime whereas it decreases concentrations. Conversely a rise in tangential Darcy number accelerates only the tangential flow and decelerates swirl flow, simultaneously depressing temperatures and concentrations. Increasing thermal slip accelerates the swirl flow and boosts concentration but serves to retard the tangential flow and decrease temperatures. With higher radiation contribution (lower Rc values) temperatures are elevated and concentrations are reduced. Verification of the MAPLE 17 solutions is achieved using a Keller-box finite difference method (KBM). A number of interesting features in the thermo-fluid and species diffusion characteristics are addressed. Key words: Stefan blowing; Spinning cone; MAPLE 17; Anisotropi

Modeling and simulation in engineering sciences

This book features state-of-the-art contributions in mathematical, experimental and numerical simulations in engineering sciences. The contributions in this book, which comprise twelve chapters, are organized in six sections spanning mechanical, aerospace, electrical, electronic, computer, materials, geotechnical and chemical engineering. Topics include metal micro-forming, compressible reactive flows, radio frequency circuits, barrier infrared detectors, fiber Bragg and long-period fiber gratings, semiconductor modelling, many-core architecture computers, laser processing of materials, alloy phase decomposition, nanofluids, geo-materials and rheo-kinetics. Contributors are from Europe, China, Mexico, Malaysia and Iran. The chapters feature many sophisticated approaches including Monte Carlo simulation, FLUENT and ABAQUS computational modelling, discrete element modelling and partitioned frequency-time methods. The book will be of interest to researchers and also consultants engaged in many areas of engineering simulation

Computational fluid dynamics simulation of a nanofluid-based annular solar collector with different metallic nano-particles

A numerical study of convective heat transfer in an annular pipe solar collector system is conducted. The inner tube contains pure water and the annular region contains nanofluid. Three-dimensional steady-state incompressible laminar flow comprising water-based nanofluid containing a variety of metallic nano-particles (copper oxide, aluminium oxide and titanium oxide nano-particles)is examined. The Tiwari-Das model is deployed for whichthermal conductivity, specific heat capacity and viscosity of the nanofluid suspensions is evaluated as a function of solid nano-particle volume fraction. Radiative heat transfer is also incorporated using the ANSYS solar flux and Rosseland radiative models. The ANSYS FLUENTfinite volume code (version 18.1) is employed to simulate the thermo-fluid characteristics. Mesh-independence tests are conducted. The influence of volume fraction on temperature, velocity, pressure contours is computed and visualized.Copper oxide nanofluid is observed to achieve the best temperature enhancement. Temperature contours at cross-sections of the annulus are also computed

Computational fluid dynamics analysis of moisture ingress in aircraft structural composite materials

Moisture in composite materials has been proven to be an important issue leading to significant deterioration of commercial aircraft wing structures. Lingering problems associated with this issue which is initiated with defects during manufacturing and finishing include delamination, de-bonding, potential fracture, debris etc. Despite extensive investigation and refinement in structural design, the water ingress problem persists as no general mitigation technique has yet been developed. Developing sustainable solutions to the water ingress problem can be very time-consuming and costly. The increasing use of composites in the aviation industry, in, for example, honeycomb sandwich components highlights the significant need to address the moisture ingress problem and develop deeper insights which can assist in combatting this problem. Experimental testing, although the most dependable approach, can take months, if not years. Numerical simulations provide a powerful and alternative approach to experimental studies for obtaining an insight into the mechanisms and impact of moisture ingress in aircraft composites. The principal advantage is that they can be conducted considerably faster, are less costly than laboratory testing, and furthermore can also utilize the results of laboratory studies to aid in visualizing practical problems. Therefore, the present study applies a computational fluid dynamics (CFD) methodology, specifically ANSYS finite volume software and the three fluid-based solvers, Fluent, CFX and ANSYS fluid structure interaction (FSI), to simulate water ingress in composite aerospace structures. It is demonstrated that ANSYS Fluent is a satisfactory computational solver for fundamental studies, providing reasonably accurate results relatively quickly, especially while simulating two-dimensional components. Three-dimensional components are ideally simulated on CFX, although the accuracy achievable is reduced. The structural-fluid based solver, ANSYS FSI (fluid structure interaction), unfortunately does not fully implement the material studied leading to reduced accuracy. The simulations reveal interesting features associated with different inlet velocities, inlet fastener hole numbers, void number and dimensions. Pressure, velocity, streamline, total deformation and normal stress plots are presented with extensive interpretation. Furthermore, some possible mitigation pathways for water ingress effects including hydrophobic coatings are outlined. KEY WORDS: Aircraft composites, Computational Fluid Dynamics, ANSYS, moisture ingress, Fluent, CFX, (fluid structure interaction) FSI, velocity, pressure, total deformation; elevator, mesh density

Finite element analysis of rotating oscillatory magneto-convective radiative micropolar thermo-solutal flow

Micropolar fluids provide an alternative mechanism for simulating micro-scale and molecular fluid mechanics which require less computational effort. In the present paper, a numerical analysis is conducted for the primary and secondary flow characterizing dissipative micropolar convective heat and mass transfer from a rotating vertical plate with oscillatory plate velocity, adjacent to a permeable medium. Owing to high temperature, thermal radiation effects are also studied. The micropolar fluid is also chemically-reacting, both thermal and species (concentration) buoyancy effects and heat source/sink are included. The entire system rotates with uniform angular velocity about an axis normal to the plate. Rosseland’s diffusion approximation is used to describe the radiative heat flux in the energy equation. The partial differential equations governing the flow problem are rendered dimensionless with appropriate transformation variables. A Galerkin finite element method is employed to solve the emerging multi-physical components of fluid dynamics problem are examined for a variety of parameters including rotation parameter, radiation-conduction parameter, micropolar coupling parameter, Eckert number (dissipation), reaction parameter, magnetic body force parameter and Schmidt number. A comparison with previously published article is made to check the validity and accuracy of the present finite element solutions under some limiting case and excellent agreement is attained. The current simulations may be applicable to various chemical engineering systems, oscillating rheometry, and rotating MHD energy generator near-wall flows

Electro-osmosis modulated viscoelastic embryo transport in uterine hydrodynamics : mathematical modelling

Embryological transport features a very interesting and complex application of peristaltic fluid dynamics. Electro-osmotic phenomena are also known to arise in embryo transfer location. The fluid dynamic environment in embryological systems is also known to be non-Newtonian and exhibits strong viscoelastic properties. Motivated by these applications, the present article develops a new mathematical model for simulating two-dimensional peristaltic transport of a viscoelastic fluid in a tapered channel under the influence of electro-osmosis induced by asymmetric zeta potentials at the channel walls. The robust Jeffrey viscoelastic model is utilized. The finite Debye layer electro-kinetic approximation is deployed. The moving boundary problem is transformed to a steady boundary problem in the wave frame. The current study carries significant physiological relevance with an ever-increasing desire to study intrauterine fluid flow motion in an artificial uterus. The consequences of this model may introduce a new mechanical factor for embryo transport to a successful implantation site. Hydrodynamic characteristics are shown to be markedly influenced by the electro-osmosis, the channel taper angle and the phase shift between the channel walls. Furthermore it is demonstrated that volumetric flow rates and axial flow are both enhanced when the electro-osmotic force aids the axial flow for specific values of zeta potential ratio. Strong trapping of the bolus (representative of the embryo) is identified in the vicinity of the channel central line when the electro-osmosis opposes axial flow. The magnitude of the trapped bolus is observed to be significantly reduced with increasing tapered channel length whereas embryo axial motility is assisted with aligned electro-osmotic force