Effects Of Various Dimensionless Parameters Research Articles

Effects of magnetism on porous rectangular fins with convection and radiation

A fin is an extended surface used to enhance the surface area of a heat transfer surface between a hot source and the outside environment. To maximise the rate of heat transportation, the exterior surface of heated equipment is equipped with fins of various geometries. Heat is exchanged using fins in radiators, refrigeration systems, superheaters, combustion engines, electrical equipment, electric transformers, space vehicles, and aircraft engines. Reflecting these applications, we analyse the effect of a magnetic field on the thermal properties of radiating porous rectangular fins. The proposed model is numerically analysed using the shooting method under the influence of radiation and convection, then compared with the DTM solution and both the solution found closer to each other. The effect of various dimensionless parameters on temperature transmission in magnetized rectangular-shaped porous fins is revealed using numerical results. It is revealed that, when the Raleigh, Hartmann, Peclet numbers, convective and radiative parameters increase, the fin?s thermal profile decreases, whereas the thermal profile increases with an increase in surface temperature, porosity, and ambient temperature. It is observed that the magnetic effect increases the heat transfer rate from porous rectangular fin surfaces. Accordingly, efficiency increases as Hartmann number, Raleigh number, and radiative parameter rise. Increasing Peclet number, surface temperature, and ambient temperature leads to a reduction in efficiency.

Physics-informed deep learning for melting heat transfer analysis with model-based transfer learning

We present an adaptive deep collocation method (DCM) based on physics-informed deep learning for the melting heat transfer analysis of a non-Newtonian (Sisko) fluid over a moving surface with nonlinear thermal radiation. Fitted neural network search (NAS) and model based transfer learning (TL) are developed to improve model computational efficiency and accuracy. The governing equations for this boundary-layer flow problem are derived using Buongiorno's and a nonlinear thermal radiation model. Next, similarity transformations are introduced to reduce the governing equations into coupled nonlinear ordinary differential equations (ODEs) subjected to asymptotic infinity boundary conditions. By incorporating physics constraints into the neural networks, we employ the proposed deep learning model to solve the coupled ODEs. The imposition of infinity boundary conditions is carried out by adding an inequality constraint to the loss function, with infinity added to the hyper-parameters of the neural network, which is updated dynamically in the optimization process. The effects of various dimensionless parameters on three profiles (velocity, temperature, concentration) are investigated. Finally, we demonstrate the performance and accuracy of the adaptive DCM with transfer learning through several numerical examples, which can be the promising surrogate model to solve boundary layer problems.

Improvement of Solar Cell Efficiency and Electrical Energy of a Photovoltaic-Thermal System by Using Nanofluid

This communication presents the finite element method (FEM) analysis of the conjugate heat transfer across the PV/T panel. The PV/T system has several layers i.e., PV cell layer, thermal paste layer, reservoir wall and reservoir flow channel filled with nanofluid. The heat transfer equations for all layers have been constructed according to the conjugate heat transfer equation. The continuity, momentum and energy equations are solved numerically by using the FEM technique. The effects of various dimensionless parameters are discussed by plotting velocity, temperature, electrical output and thermal efficiencies. The result indicates that the average cell temperature keeps decreased by increasing nanoparticle concentration. The narrower flow channel has greater power output at the relatively low concentration while the wider flow channel has greater power output at the relatively high concentration. Thermal performance increases by 11% for every 10% increasing in nanoparticle volume fraction.

A computational study on the MHD Casson fluid flow with thermal radiation and variable physical properties under the influence of Soret and Dufour effects

AbstractThis research study discusses the flow of a magnetohydrodynamic Casson fluid under the influence of Soret, Dufour, and thermal radiation. Nonlinear partial differential equation (PDE) of governing equations is transformed into a dimensionless version of the modified PDEs presented in terms of dimensionless parameters. The solution of coupled PDEs is obtained by the finite difference method with a combination of the quasilinearization technique. The effects of various dimensionless parameters are shown graphically, such as buoyancy force (), concentration buoyancy force , Casson parameter (), magnetic parameter (), thermal radiation (), Darcy parameter (), Forchheimer (fr), Dufour (), Soret (Sor), Brownian motion (), thermopohersis (), and Lewis number (). Prevention of heat transfer in the industrial system is critical, the velocity behavior (), thermal variation (), and concentration profile () are more prominent in the roles of coal, gas, and solar thermal collectors.

Effect of inclined magnetic field on flow of Williamson nanofluid over an exponentially stretching surface in Darcy‐Forchheimer model

AbstractThe present study elaborates magnetohydrodynamics (MHD) boundary layer flow with heat and mass transfer of pseudo‐plastic nanofluid over an exponentially stretching sheet embedded in a porous medium. Also, the effects of Brownian motion and thermophoresis on heat transfer and nanoparticle concentration are taken into account. With the help of suitable similarity transformations, the governing partial differential equations (PDEs) are transformed into a system of ordinary differential equations (ODEs). An inbuilt solver of MATLAB is being used to solve the system of mathematical equations. The effects of dimensionless parameters on the flow, heat transfer and nanoparticle concentration have been investigated. Graphs have been plotted and discussed to analyze the effects of various dimensionless parameters on velocity, temperature and concentration. As per the results, fluid velocity diminishes as the values of the aligned angle elongate, although temperature and concentration profiles reflect a switch pattern. Furthermore, as the values of Brownian motion, thermophoresis parameter and Lewis number rise, the temperature and concentration profiles rise as well. However, the concentration profiles for Brownian motion and Lewis number shows the reverse tendency.

Thermal Effect on the Instability of Annular Liquid Jet

The linear instability of an annular liquid jet with a radial temperature gradient in an inviscid gas steam is investigated theoretically. A physical model of an annular liquid jet with a radial temperature gradient is established, dimensionless governing equations and boundary conditions are given, and numerical solutions are obtained using the spectral collocation method. The correctness of the results is verified to a certain extent. The liquid surface tension coefficient is assumed to be a linear function of temperature. The effects of various dimensionless parameters (including the Marangoni number/Prandtl number, Reynolds number, temperature gradient, Weber number, gas-to-liquid density ratio and velocity ratio) on the instability of the annular liquid jet are discussed. A decreasing Weber number destabilizes the annular liquid jet when the Weber number is lower than a critical value. It is found that the effects of the Marangoni effect are related to the Weber number. The Marangoni effect enhances instability when the Weber number is small, while the Marangoni effect weakens instability when the Weber number is large. In addition, because the thermal effect is considered, a decreasing Reynolds number enhances the instability when the Weber number is lower than a critical value, which is similar to the results of a viscous liquid sheet with a temperature difference between two planar surfaces. Furthermore, the effects of other dimensionless parameters are also investigated.

Effect of first order chemical reactions through tissue-blood interface on the partial pressure distribution of inhaled gas

Gas exchange is an essential process to get fresh oxygenated air from the environment. In the human respiratory system, partial pressure is responsible for exchanging gas between tissue-blood capillary (inter capillary). However, the mechanisms of partial pressure distribution in the human respiratory system remain incompletely understood in terms of inter-capillary transmission with tissue porosity and reactive boundary conditions. In this paper, we worked on the spatial (radial) and temporal variations of inhaled gas partial pressure through inter capillary. We assumed that the tissue of alveoli is porous and the material of blood capillary is absorptive and reactive and gas could bear linear first-order kinetic reactions, one is reversible among the material of blood capillary and the other is irreversible into the surrounding tissue. Mathematical modeling is done by using diffusion equation; and the effect of various dimensionless parameters e.g. the Damkohler number (DA), phase partitioning number (α), dimensionless absorption number (Γ) are analyzed. Numerical simulation shows that an increment in porosity does not change convection speed but the diffusion of gas increases in alveolar tissue, resultantly, partial pressure gradient of the gas decreases in tissue and increases in blood capillary. However, by increasing the breathing rate, the partial pressure of the gas inside the blood first decreases, and after some time it increases gradually with the breathing rate. Additionally, the dispersion coefficient advanced toward its steady-state in a short time at absorption rate 0.1 and Damkohler number while long-time dispersion is achieved at porosity ϵ = 0.9, absorption rate Γ = 1, and phase exchange rate Ultimately, the findings of this study can be helpful for a better understanding of dispersion through human lung affected by aging and various lung diseases.

Hydrodynamic effect of slip boundaries and exponentially decaying/growing time-dependent pressure gradient on Dean flow

Hydrodynamic behaviour of slip flow and radially applied exponential time-dependent pressure gradient in a curvilinear concentric cylinder is examined. A two-step method of solution has been utilized in resolving the governing momentum equation. Accordingly, the exact solution of the time-dependent partial differential equation is derived in terms of the Laplace parameter. Afterwards, the Laplace domain solution is then inverted to time domain using a numerical-based inverting scheme known as Riemann-sum approximation. The effect of various dimensionless parameters involved in the problem on the Dean velocity, shear stresses and Dean vortices is discussed with the aid of graphs. It is found that maximum Dean velocity is due to an exponentially growing time-dependent pressure gradient and slip wall coefficient. Stability of the Dean vortices is achieved by suppressing time, wall slippage and inducing an exponentially decaying time-dependent pressure gradient.

Unsteady MHD squeezing viscous Casson fluid flow in upright channel with cross-diffusion and thermal radiactive effects

The purpose of the present work is to analyse two-dimensional unsteady squeezing Casson fluid flow between porous channel along with cross-diffusion, viscous dissipation, radiation, and chemical reaction effects. To get the results of governing equations which are partial differential equations in nature, we have converted them into ordinary differential equations by utilizing suitable similarity transformation and then applied the optimal homotopy analysis method. The effects of various dimensionless parameters ascended in the velocity, temperature and concentration fields are discussed through graphs. Values of skin friction coefficient, Nusselt number, and Sherwood coefficients are derived and presented in tabular form. Results indicate that with enhancement in the values of the Casson parameter and magnetic parameter, the velocity decreases near the lower plate while it shows reverse behaviour near the upper one. The temperature of the fluid increases with an increase in both radiation parameter as well as with Eckert number while it decreases by augmenting values of the Casson parameter. Soret and Dufour number affect mass and heat transfer rate in reverse manner. Also, concentration decreases when chemical reaction parameter increases.

Numerical Simulation of MHD Stagnation Point Flow of Micropolar Heat Generating and Dissipative Nanofluid : SLM Approach

In the present paper, we study the magnetohydrodynamic stagnation point flow dealing with heat and mass transfer of a micropolar nanofluid influenced with heat generation and viscous dissipation. Nonlinear ordinary differential equations are obtained by applying suitable similarity transformation on the governing partial differential equations. These differential equations have been solved by successive linearization method (SLM). The effects of various dimensionless parameters, such as heat generation parameter, thermophoretic parameter and stagnation parameter on the flow field, are discussed through tables and graphs by accumulating sufficient data using SLM. Results show many important facts, including temperature distribution gradual increment with the increase of heat generation and microrotation parameters. Quadratic multiple regression analysis has been performed for skin friction coefficient, local Sherwood number and local Nusselt number. When free stream velocity and stretching velocity are equal, variation in microrotation and magnetic field leads to very low perturbation in skin friction, local Sherwood number and local Nusselt number, whereas when free stream velocity is dominant over stretching velocity, there occurs reverse heat flow at the surface of the sheet.

Numerical Simulation of Wave Interaction with Submerged Porous Structures and Application for Coastal Resilience

Srineash, V.K.; Kamath, A.; Murali, K., and Bihs, H., 2020. Numerical simulation of wave interaction with submerged porous structures and application for coastal resilience. Journal of Coastal Research, 36(4), 752–770. Coconut Creek (Florida), ISSN 0749-0208.The study of wave interaction with porous structures is essential as coastal structures are often porous in nature because of their prominent energy dissipation characteristics. The present work is focused on the numerical modeling of wave interaction with submerged porous structures, which are often classified as reef breakwaters and low-crested structures. Numerical modeling of wave interaction with porous structures is considered to be a challenge for researchers because of the complexities associated with it. The present study numerically investigates the wave interaction process through the porous media by representing the porous media using Volume-averaged Reynolds-Averaged Navier–Stokes (VRANS) equations. For the study, an open-source RANS-based computational fluid dynamics tool, REEF3D, has been used for numerical modeling. The study also consists of experiments that are used for validating the numerical model. The numerical results for the free-surface elevation and the hydrodynamic pressure are compared with the experimental measurements and found to be in good agreement. The numerical study is extended to different crest widths of the structure and varying wave parameters to investigate the effects of various dimensionless parameters affecting wave transmission. The frequency-domain analysis is performed to investigate the energy distribution of the incident and transmitted waves. Finally, the utility of the numerical model adopting VRANS equations has been demonstrated for climate-change mitigation studies. This has been carried out by studying the effects of pressure reduction on a vertical seawall due to the presence of a porous reef breakwater in the sea side. Pressure reduction up to 32% is calculated because of the presence of the porous structure in front of the seawall and this demonstrates the application of reef breakwaters for coastal resilience studies. Such investigations are useful in protecting the existing coastal structures prone to severe wave conditions exceeding the design limits.

Chemical reaction and heat source/sink effect on magnetonano Prandtl-Eyring fluid peristaltic propulsion in an inclined symmetric channel

The main emphasis of this article is to examine the peristaltic transport of magnetohydrodynamic (MHD) Prandtl-Eyring nanofluid in an inclined symmetric channel with compliant walls. Nanofluid including thermophoresis and Brownian motion is taken into account. Two-dimensional governing equations for the peristaltic motion of Prandtl-Eyring nanofluid are modeled in the presence of chemical reaction. The resulting dimensionless nonlinear system is numerically solved for velocity, temperature, and concentration. The effects of various dimensionless parameters on fluid flow are featured through graphs. This analysis reveals that the influence of wall tension and wall mass parameters on axial velocity are increasing whereas the impact of wall damping parameter on velocity is decaying. The opposite effect of thermophoresis parameter and Brownian motion parameter on both temperature and heat transfer coefficient are observed. The destructive chemical reaction causes decay in temperature, nanoparticle concentration, and heat transfer coefficient.

Study of Effects of Dimensionless Parameters on Thermal Efficiency of Enhanced Solar Liquid Collector with Coiled Wire Inserts

Solar liquid collectors are good candidate of heat transfer enhancement. The efficiency of a solar liquid collector can be improved by augmenting tube side heat transfer using enhanced techniques used in heat exchangers. Various types of heat transfer enhancement techniques has been used in heat exchangers which are mainly classified in two types, active and passive techniques. Solar liquid collectors can also be enhanced by these active and passive devices. Passive techniques, mainly swirl flow devices are more popular enhancement techniques in solar liquid collectors as they do not require any external source of power and also they do not affect the mechanical strength of tube material. Initially twisted tape inserts and conical inserts were popular passive devices used in enhanced solar liquid collectors mainly because of availability of established correlations. Wire coil inserts are relatively less experimented passive technique. This study is focused on tube side heat transfer augmentation of a solar flat plate liquid collector by wire coil inserts and effect of various dimensionless parameters on thermal efficiency of solar collector.

The Impact of Radiation Effect on MHD Stagnation-Point Flow of a Nanofluid over an Exponentially Stretching Sheet in the Presence of Chemical Reaction

The present study is to investigate the effect of the chemical reaction parameter on stagnation point flow of magnetohydrodynamics field past an exponentially stretching sheet by considering a nanofluid. The problem is governed by governing coupled nonlinear partial differential equations with appropriate boundary conditions. The transformed non-dimensional and coupled governing ordinary differential equations are solved numerically using the fourth order Adams-Bashforth Moulton method. The effects of various dimensionless parameters on velocity, temperature and concentration fields are studied and then the results are presented in both tabular and graphical forms.

Effect of first order chemical reactions on the dispersion coefficient associated with laminar flow through fibrosis affected lung

In this paper, we worked on the effective area average concentration and dispersion coefficient associated with the unsteady flow, to understand the dispersion in the fibrosis-affected lung. We assumed that the tube wall (i.e. alveolar or pulmonary capillary wall) is thicker than its normal size due to fibrosis and chemical species may go through linear first-order kinetic reactions, one is reversible phase exchange with the wall material and other is irreversible absorption into the tube wall. By considering diffusivity as a function of thickness, the dispersion can be calculated by the distribution of concentration of gas along a tube. Mathematical modeling is done by using diffusion equation; and effects of various dimensionless parameters e.g., the Damkohler number (DA), phase partitioning number (α), dimensionless absorption number (Γ), thickness and permeability of wall are observed. Numerical simulation shows that the diffusion rate through the respiratory wall is decreased significantly as the thickness of wall increases, while it increased with the increment in the porosity of wall, the concentration of species increased when the tube wall thickness increases; which cause reduction in the spread of the species; additionally, the dispersion coefficient achieves the steady-state values in a very short time when 0 < DA ⩽1 and absorption rate < 1, while for 1 < DA ⩽20 and absorption rate = 1 long time dispersion is achieved.

Impact of Heat Transfer and Viscous Dissipation on Unsteady MHD oscillatory Dusty Fluid Flow Through a Vertical Porous Channel

This work discusses the effect of heat transfer and viscous dissipation on unsteady MHD (Magneto Hydro Dynamic or Hydromagnetic) oscillatory dusty fluid flow through a vertical porous channel. The governing equations for both fluid and particle phase are solved separately to get the exact solution for velocity and temperature profiles. The effect of various dimensionless parameters are displayed graphically and discussed qualitatively.

Interfacial instability in pressure-driven core-annular pipe flow of a Newtonian and a Herschel–Bulkley fluid

The linear stability characteristics of pressure-driven core-annular flow of a Newtonian core fluid and a Herschel–Bulkley annular fluid is investigated. The fluids are assumed to have the same density and separated by a sharp interface. The modified Orr–Sommerfeld equations for each layer are derived and solved using an efficient spectral collocation method considering a configuration without any unyielded region. The effect of various dimensionless parameters, such as the Bingham number (Bn), the flow index (n), the interface radius (R0) and the inverse capillary number (Γ) on the instability characteristics of the flow is investigated, and an energy budget analysis is conducted to explain the physical mechanism of the instability observed. We found that axisymmetric mode is the most dominant unstable mode for the interfacial flow configuration considered in the present work, which is in contrast to miscible core-annular flows. It is observed that increasing Bn has a non-monotonic effect on the growth rate of the axisymmetric mode, and two dominant modes appear at high Bn. We found that increasing the thickness of the core fluid increases the bandwidth of the unstable wavenumbers and destabilises the short waves; however, displays a non-monotonic trend in the growth rate curves. The instability behaviour observed for different sets of parameters are investigated by conducting an energy budget analysis and analysing the disturbance eigenfunctions and the basic velocity profiles.

Effects of Velocity and Thermal Slip Conditions with Radiation on Heat Transfer Flow of Ferrofluids

To analyze the thermal convection of ferrofluid along a flat plate is the persistence of this study. The two-dimensional laminar, steady, incompressible flow past a flat plate subject to convective surface boundary condition, slip velocity in the presence of radiation has been studied where the magnetic field is applied in the transverse direction to the plate. Two different kinds of magnetic nanoparticles, magnetite Fe3O4 and cobalt ferrite CoFe2O4 are amalgamated within the base fluids water and kerosene. The effects of various physical aspects such as magnetic field, volume fraction, radiation and slip conditions on the flow and heat transfer characteristics are presented graphically and discussed. The effect of various dimensionless parameters on the skin friction coefficient and heat transfer rate are also tabulated. To investigate this particular problem, numerical computations are done using the implicit finite difference method based Keller-Box Method.

Dufour Effects on Unsteady MHD Convective Heat and Mass Transfer Flow of Micropolar Fluid Past a Vertical Moving Porous Plate

An investigation of Dufour effects on unsteady MHD convective flow of micropolar fluid past a vertical moving semi-infinite plate embedded in a porous medium is carried out. The dimensionless governing equations for this investigation are solved analytically using small perturbation approximation. The effect of various dimensionless parameters entering into the problem on the velocity, temperature and concentration profiles across the boundary layer are investigated through graphs. Also, the result of the skin friction coefficient, the rate of heat and mass transfer at the wall are prepared with various values of the parameters. It is observed that the velocity increases with the increase of Dufour number whereas it decreases with the increasing value of Schmidt number, Prandtl number and Eckert number. Also, magnitude of micro rotation increases with the increase of Eckert number.

Boundary Layer Analysis in Nanofluid Flow Past a Permeable Moving Wedge in Presence of Magnetic Field by Using Falkner – Skan Model

In the present work, the effect of various dimensionless parameters on the momentum, thermal and concentration boundary layer are analyzed. In this respect we have considered the MHD boundary layer flow of heat and transfer over a porous wedge surface in a nanofluid. The governing partial differential equations are converted into ordinary differential equations by using the similarity transformation. These ordinary differential equations are numerically solved using fourth order Runge–Kutta method along with shooting technique. The present results have been shown in a graphical and also in tabular form. The results indicate that the momentum boundary layer thickness reduces with increasing values of the pressure gradient parameter β for different situations and also for the magnetic parameter &lt;i&gt;M&lt;/i&gt; but increases for the velocity ratio parameter λ and permeability parameter &lt;i&gt;K&lt;/i&gt;*. The heat transfer rate increases for the pressure gradient parameter β, velocity ratio parameter λ, Brownian motion parameter Nb and Prandtl number Pr but opposite result is found for the increasing values of the thermoporesis parameter &lt;i&gt;Nt&lt;/i&gt;. The nanoparticle concentration rate increases with an increase in the pressure gradient parameter β, velocity ratio parameter λ, Brownian motion parameter Nb and Lewis number Le, but decreases for the thermoporesis parameter &lt;i&gt;Nt&lt;/i&gt;. Finally, the numerical results has compared with previously published studies and found to be in good agreement. So the validity of our results is ensured.