Flow structure and heat transfer analysis of the floatation nozzle with a moving wall

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tianlun Huang ◽  
Zhiming Yang ◽  
Simian Diao ◽  
Zhigao Huang ◽  
Yun Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Structure ◽  
Design Methodology ◽  
Wall Motion ◽  
Separation Distance ◽  
Heat Transfer Analysis ◽  
Content Type ◽  
Slot Nozzle ◽  
Moving Wall ◽  
Pressure Distributions

Purpose This study aims to investigate the effects of different surface-to-jet velocity ratios (Rsj) on the flow structure and the heat transfer of the floatation nozzle under different ratios (h/w) of the separation distance (h) to the slot width (w) and the differences of the flow structure and the heat transfer between the floatation nozzle and the slot nozzle. Design/methodology/approach The Nusselt number (Nu) and the pressure distribution of the floatation nozzle with a stationary wall are measured. Then the experimental results are used to validate the numerical model. Finally, a series of numerical simulations is carried out to achieve the purpose of this study. Findings The flow structure and heat transfer differences between the floatation nozzle and the slot nozzle are clarified. The floatation nozzle has more than 18 times the floatation ability of the unconfined slot nozzle. The Nu and pressure distributions of the floatation nozzle are experimentally measured. The effects of wall motion on the Nu and pressure distributions are identified. Originality/value The effects of the wall motion on the flow structure and the heat transfer of the floatation nozzle, and the differences between the floatation nozzle and the slot nozzle are first obtained. Therefore, it is valuable for engineers in engineering design of the floatation nozzle.

Importance of convective heat transfer in flow of non-Newtonian nanofluid featuring Brownian and thermophoretic diffusions

2019 ◽  
Vol 29 (12) ◽  
pp. 4624-4641 ◽  
Author(s):  
Waqar Azeem Khan ◽  
Mehboob Ali ◽  
Muhammad Waqas ◽  
M. Shahzad ◽  
F. Sultan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Convective Heat Transfer ◽  
Design Methodology ◽  
Numerical Solutions ◽  
Pressure Profile ◽  
Boundary Region ◽  
Heat Transfer Analysis ◽  
Content Type ◽  
Source Sink

Purpose This paper aims to address the flow of Sisko nanofluid by an unsteady curved surface. Non-uniform heat source/sink is considered for heat transfer analysis. Design/methodology/approach Numerical solutions are constructed using bvp4c procedure. Findings Pressure profile inside boundary region is increased when A and K are enhanced. Originality/value No such analysis is yet presented.

Influence of Cattaneo-Christov heat flux in flow of an Oldroyd-B fluid with variable thermal conductivity

2016 ◽  
Vol 26 (7) ◽  
pp. 2271-2282 ◽  
Author(s):  
Fahad Munir Abbasi ◽  
Sabir Ali Shehzad ◽  
T. Hayat ◽  
A. Alsaedi ◽  
A. Hegazy
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Design Methodology ◽  
Nonlinear Problems ◽  
Variable Thermal Conductivity ◽  
Heat Transfer Analysis ◽  
Content Type ◽  
Flux Model ◽  
Heat Flux Model

Purpose The purpose of this paper is to introduce the Cattaneo-Christov heat flux model for an Oldroyd-B fluid. Design/methodology/approach Cattaneo-Christov heat flux model is utilized for the heat transfer analysis instead of Fourier’s law of heat conduction. Analytical solutions of nonlinear problems are computed. Findings The authors found that the temperature is decreased with an increase in relaxation time of heat flux but temperature gradient is enhanced. Originality/value No such analysis exists in the literature yet.

Algebraic solutions of flow and heat for some nanofluids over deformable and permeable surfaces

2017 ◽  
Vol 27 (10) ◽  
pp. 2259-2267 ◽  
Author(s):  
Mustafa Turkyilmazoglu
Keyword(s):  
Heat Transfer ◽  
Design Methodology ◽  
Temperature Jump ◽  
Volume Fraction ◽  
Velocity Slip ◽  
Jump Conditions ◽  
Content Type ◽  
Layer Flow ◽  
Working Out ◽  
Algebraic Solutions

Purpose This paper aims to working out exact solutions for the boundary layer flow of some nanofluids over porous stretching/shrinking surfaces with different configurations. To serve to this aim, five types of nanoparticles together with the water as base fluid are under consideration, namely, Ag, Cu, CuO, Al2O3 and TiO2. Design/methodology/approach The physical flow is affected by the presence of velocity slip as well as temperature jump conditions. Findings The knowledge on the influences of nanoparticle volume fraction on the practically significant parameters, such as the skin friction and the rate of heat transfer, for the above considered nanofluids, is easy to gain from the extracted explicit formulas. Originality/value Particularly, formulas clearly point that the heat transfer rate is not only dependent on the thermal conductivity of the material but it also highly relies on the heat capacitance as well as the density of the nanofluid under consideration.

Unsteady separated stagnation-point flow and heat transfer past a stretching/shrinking sheet in a copper-water nanofluid

2019 ◽  
Vol 29 (8) ◽  
pp. 2588-2605 ◽  
Author(s):  
Natalia C. Roşca ◽  
Alin V. Roşca ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Partial Differential Equations ◽  
Differential Equations ◽  
Stagnation Point ◽  
Design Methodology ◽  
Similarity Transformation ◽  
Stagnation Point Flow ◽  
Shrinking Sheet ◽  
Content Type ◽  
Flow And Heat Transfer

Purpose The purpose of this paper is to theoretically investigate the unsteady separated stagnation-point flow and heat transfer past an impermeable stretching/shrinking sheet in a copper (Cu)-water nanofluid using the mathematical nanofluid model proposed by Tiwari and Das. Design/methodology/approach A similarity transformation is used to reduce the governing partial differential equations to a set of nonlinear ordinary (similarity) differential equations which are then solved numerically using the function bvp4c from Matlab for different values of the governing parameters. Findings It is found that the solution is unique for stretching case; however, multiple (dual) solutions exist for the shrinking case. Originality/value The authors believe that all numerical results are new and original, and have not been published elsewhere.

MHD slip flow and convective heat transfer due to a moving plate with effects of variable viscosity and thermal conductivity

2020 ◽  
Vol 16 (5) ◽  
pp. 991-1018
Author(s):  
Mahantesh M. Nandeppanavar ◽  
M.C. Kemparaju ◽  
R. Madhusudhan ◽  
S. Vaishali
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Boundary Layer ◽  
Differential Equations ◽  
Radiation Effects ◽  
Variable Viscosity ◽  
Heat Transfer Analysis ◽  
Concentration Profiles ◽  
Moving Plate ◽  
Content Type

PurposeThe steady two-dimensional laminar boundary layer flow, heat and mass transfer over a flat plate with convective surface heat flux was considered. The governing nonlinear partial differential equations were transformed into a system of nonlinear ordinary differential equations and then solved numerically by Runge–Kutta method with the most efficient shooting technique. Then, the effect of variable viscosity and variable thermal conductivity on the fluid flow with thermal radiation effects and viscous dissipation was studied. Velocity, temperature and concentration profiles respectively were plotted for various values of pertinent parameters. It was found that the momentum slip acts as a boost for enhancement of the velocity profile in the boundary layer region, whereas temperature and concentration profiles decelerate with the momentum slip.Design/methodology/approachNumerical Solution is applied to find the solution of the boundary value problem.FindingsVelocity, heat transfer analysis is done with comparing earlier results for some standard cases.Originality/value100

Numerical analysis of a hybrid tubular and cavity air receiver for solar thermal applications

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sayuj Sasidharan ◽  
Pradip Dutta
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Analysis ◽  
Heat Loss ◽  
Solar Thermal ◽  
Heat Transfer Analysis ◽  
Receiver Design ◽  
Radiation Emission ◽  
Content Type ◽  
Thermal Receiver

Purpose This paper aims to deal with characterisation of the thermal performance of a hybrid tubular and cavity solar thermal receiver. Design/methodology/approach The coupled optical-flow-thermal analysis is carried out on the proposed receiver design. Modelling is performed in two and three dimensions for estimating heat loss by natural convection for an upward-facing cavity. Heat loss obtained in two dimensions by solving coupled continuity, momentum and energy equation inside the cavity domain is compared with the loss obtained using an established Nusselt number correlation for realistic receiver performance prediction. Findings It is found that radiation emission from a heated cavity wall to the ambient is the dominant mode of heat loss from the receiver. The findings recommend that fluid flow path must be designed adjacent to the surface exposed to irradiation of concentrated flux to limit conduction heat loss. Research limitations/implications On-sun experimental tests need to be performed to validate the numerical study. Practical implications Numerical analysis of receivers provides guidelines for effective and efficient solar thermal receiver design. Social implications Pressurised air receivers designed from this method can be integrated with Brayton cycles using air or supercritical carbon-dioxide to run a turbine generating electricity using a solar heat source. Originality/value The present paper proposes a novel method for coupling the flux map from ray-tracing analysis and using it as a heat flux boundary condition for performing coupled flow and heat transfer analysis. This is achieved using affine transformation implemented using extrusion coupling tool from COMSOL Multiphysics software package. Cavity surface natural convection heat transfer coefficient is obtained locally based on the surface temperature distribution.

Numerical simulation of Nusselt-Rayleigh correlation in Bénard cells. A solution based on the network simulation method

2015 ◽  
Vol 25 (5) ◽  
pp. 986-997 ◽  
Author(s):  
Manuel Cánovas ◽  
Iván Alhama ◽  
Emilio Trigueros ◽  
Francisco Alhama
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Porous Media ◽  
Design Methodology ◽  
Network Simulation ◽  
Simulation Method ◽  
Extensive Study ◽  
Dimensionless Number ◽  
Content Type ◽  
Network Simulation Method

Purpose – Natural convection with heat transfer in porous media has been subject of extensive study in engineering due to its numerous applications. A case of particular interest is the Bénard-type flow.The paper aims to discuss this issue. Design/methodology/approach – Based on the network simulation method in order to solve this problem, a numerical model is proposed. Findings – Nusselt-Rayleigh correlation is determined for a broad range of Rayleigh, the dimensionless number that influences the solution, above and below the threshold which separates the conduction and convection pure mechanisms. Originality/value – Based on the network simulation method.

Numerical solution of mixed convection in a lid-driven cavity with arc-shaped moving wall

2017 ◽  
Vol 34 (3) ◽  
pp. 869-891 ◽  
Author(s):  
Muneer A. Ismael
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Numerical Solution ◽  
Rotational Speed ◽  
Uniform Mesh ◽  
Content Type ◽  
Driven Cavity ◽  
Moving Wall ◽  
Mesh Grid ◽  
Rayleigh Numbers

Purpose This paper investigates a numerical treatment to steady mixed convection in a lid-driven square cavity with arc-shaped moving wall or lid. The horizontal walls are thermally insulated. The vertical left wall is kept isothermally at high temperature, while the right arc-shaped moving wall is kept isothermally at low temperature. Design/methodology/approach Finite difference method in Cartesian coordinates with the upwind scheme is used in numerical solution. The irregular curved boundary has been treated by invoking non-uniform mesh grid with the ability to generate boundary fitted nodes. Jensen’s formulas of Neumann’s boundary condition have derived for the non-uniform mesh grid. The arc-shaped moving wall is considered as a segment of a rotating cylinder; thus, the studied pertinent parameters are the rotational speed of the arc-shaped wall in both aiding and opposing directions ω = −1,000-1,000, the arc-wall radius Ro = 0.5099-1.534 which is governed by its center (X0, Y0) = (1.1, 0.5)-(2.45, 0.5) and the Rayleigh number Ra = 103 − 106. Findings The results have shown that for low Rayleigh numbers, the rotational speed enhances heat transfer irrespective to the direction of rotation, while for high Rayleigh numbers, the aiding anticlockwise rotation (negative ω) enhances the heat transfer, while the opposing clockwise rotation (positive ω) manifests a retardation effect on the heat transfer. For a motionless arc-wall, its radius is ineffective for aiding heat transfer, while for non-zero arc-shaped wall speed, the heat transfer is an increasing function of its radius. Originality/value The arc-shaped moving wall has never been investigated until now. Therefore, the originality of this paper is due to studying the mixed convection in a lid-driven cavity with moving arc-shaped wall and inspecting the effect of its curvature and rotational speed in both directions on the flow and thermal fields.

Upward and downward conjugate mixed convection heat transfer in a partially porous cavity

2016 ◽  
Vol 26 (1) ◽  
pp. 159-188 ◽  
Author(s):  
Abderrahim Bourouis ◽  
Abdeslam Omara ◽  
Said Abboudi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mixed Convection ◽  
Transfer Rate ◽  
Vertical Wall ◽  
Thermal Conductivity Ratio ◽  
Conductivity Ratio ◽  
Content Type ◽  
Moving Wall ◽  
The Right

Purpose – The purpose of this paper is to provide a numerical study of conjugate heat transfer by mixed convection and conduction in a lid-driven enclosure with thick vertical porous layer. The effect of the relevant parameters: Richardson number (Ri=0.1, 1, 10) and thermal conductivity ratio (Rk=0.1, 1, 10, 100) are investigated. Design/methodology/approach – The studied system is a two dimensional lid-driven enclosure with thick vertical porous layer. The left vertical wall of the enclosure is allowed to move in its own plane at a constant velocity. The enclosure is heated from the right vertical wall isothermally. The left and the right vertical walls are isothermal but temperature of the outside of the right vertical wall is higher than that of the left vertical wall. Horizontal walls are insulated. The governing equations are solved by finite volume method and the SIMPLE algorithm. Findings – From the finding results, it is observed that: for the two studied cases, heat transfer rate along the hot wall is a decreasing function of thermal conductivity ratio irrespective of Richardson numbers contrary to the heat transfer rate along the fluid-porous layer interface which is an increasing function of thermal conductivity ratio. At forced convection dominant regime, the difference between heat transfer rate for upward and downward moving wall is insensitive to the thermal conductivity ratio. For downward moving wall, average Nusselt number is higher than that of upward moving wall. Practical implications – Some applications: building applications, furnace design, nuclear reactors, air solar collectors. Originality/value – From the bibliographic work and the authors’ knowledge, the conjugate mixed convection in lid-driven partially porous enclosures has not yet been investigated which motivates the present work that represent a continuation of the preceding investigations.

Effect of thickness and thermal conductivity of metal foams filled in a vertical channel – a numerical study

2019 ◽  
Vol 29 (1) ◽  
pp. 184-203 ◽  
Author(s):  
Banjara Kotresha ◽  
N. Gnanasekaran
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Metal Foam ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Vertical Channel ◽  
Metal Foams ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Content Type

PurposeThis paper aims to discuss about the two-dimensional numerical simulations of fluid flow and heat transfer through high thermal conductivity metal foams filled in a vertical channel using the commercial software ANSYS FLUENT.Design/methodology/approachThe Darcy Extended Forchheirmer model is considered for the metal foam region to evaluate the flow characteristics and the local thermal non-equilibrium heat transfer model is considered for the heat transfer analysis; thus the resulting problem becomes conjugate heat transfer.FindingsResults obtained based on the present simulations are validated with the experimental results available in literature and the agreement was found to be good. Parametric studies reveal that the Nusselt number increases in the presence of porous medium with increasing thickness but the effect because of the change in thermal conductivity was found to be insignificant. The results of heat transfer for the metal foams filled in the vertical channel are compared with the clear channel in terms of Colburn j factor and performance factor.Practical implicationsThis paper serves as the current relevance in electronic cooling so as to open up more parametric and optimization studies to develop new class of materials for the enhancement of heat transfer.Originality/valueThe novelty of the present study is to quantify the effect of metal foam thermal conductivity and thickness on the performance of heat transfer and hydrodynamics of the vertical channel for an inlet velocity range of 0.03-3 m/s.

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