scholarly journals Hybrid Nanofluid Flow Past a Shrinking Cylinder with Prescribed Surface Heat Flux

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1493
Author(s):  
Najiyah Safwa Khashi’ie ◽  
Iskandar Waini ◽  
Nurul Amira Zainal ◽  
Khairum Hamzah ◽  
Abdul Rahman Mohd Kasim
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Flux ◽  
Flat Plate ◽  
Surface Heat Flux ◽  
Numerical Study ◽  
Surface Heat ◽  
Hybrid Nanofluid ◽  
Suction Parameter ◽  
Hybrid Nanofluids

This numerical study was devoted to examining the occurrence of non-unique solutions in boundary layer flow due to deformable surfaces (cylinder and flat plate) with the imposition of prescribed surface heat flux. The hybrid Al2O3-Cu/water nanofluid was formulated using the single phase model with respective correlations of hybrid nanofluids. The governing model was simplified by adopting a similarity transformation. The transformed differential equations were then numerically computed using the efficient bvp4c solver with the ranges of the control parameters 0.5%≤ϕ1,ϕ2≤1.5% (Al2O3 and Cu volumetric concentration), 0≤K≤0.2 (curvature parameter), 2.6<S≤3.2 (suction parameter) and −2.5<λ≤0.5 (stretching/shrinking parameter). Dual steady solutions are presentable for both a cylinder (K>0) and a flat plate (K=0) with the inclusion of only the suction (transpiration) parameter. The real and stable solutions were mathematically validated through the stability analysis. The Al2O3-Cu/water nanofluid with ϕ1=0.5% (alumina) and ϕ2=1.5% (copper) has the highest skin friction coefficient and heat transfer rate, followed by the hybrid nanofluids with volumetric concentrations (ϕ1=1%,ϕ2=1%) and (ϕ1=1.5%,ϕ2=0.5%), respectively. Surprisingly, the flat plate surface abates the separation of boundary layer while it enhances the heat transfer process.

scholarly journals Convective Flow Of Micropolar Fluids Along An Inclined Flat Plate With Variable Electric Conductivity And Uniform Surface Heat Flux

1970 ◽  
Vol 6 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Md Jashim Uddin
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Flux ◽  
Differential Equations ◽  
Flat Plate ◽  
Electric Conductivity ◽  
Surface Heat Flux ◽  
Convective Flow ◽  
Surface Heat ◽  
Micropolar Fluids

Magnetohydrodynamic (MHD) twodimensional steady convective flow and heat transfer of micropolar fluids flow along an inclined flat plate with variable electric conductivity and uniform surface heat flux has been analyzed numerically in the presence of heat generation. With appropriate transformations the boundary layer partial differential equations are transformed into nonlinear ordinary differential equations. The local similarity solutions of the transformed dimensionless equations for the velocity flow, microrotation and heat transfer characteristics are assessed using Nachtsheim- Swigert shooting iteration technique along with the sixth order Runge-Kutta-Butcher initial value solver. Numerical results are presented graphically in the form of velocity, microrotation, and temperature profiles within the boundary layer for different parameters entering into the analysis. The effects of the pertinent parameters on the local skin-friction coefficient (viscous drag), plate couple stress and the rate of heat transfer (Nusselt number) are also discussed and displayed graphically. Keywords: Convective flow; Micropolar fluid; Heat transfer; Electric conductivity; Inclined plate; Locally self-similar solution DOI: http://dx.doi.org/10.3329/diujst.v6i1.9336 DIUJST 2011; 6(1): 69-79

Hybrid nanofluid flow and heat transfer past a vertical thin needle with prescribed surface heat flux

2019 ◽  
Vol 29 (12) ◽  
pp. 4875-4894 ◽  
Author(s):  
Iskandar Waini ◽  
Anuar Ishak ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Dual Solutions ◽  
Hybrid Nanofluid ◽  
Nanofluid Flow ◽  
Needle Size ◽  
Content Type ◽  
Flow And Heat Transfer

Purpose The purpose of this paper is to study the steady mixed convection hybrid nanofluid flow and heat transfer past a vertical thin needle with prescribed surface heat flux. Design/methodology/approach The governing partial differential equations are transformed into a set of ordinary differential equations by using a similarity transformation. The transformed equations are then solved numerically using the boundary value problem solver (bvp4c) in Matlab software. The features of the skin friction coefficient and the local Nusselt number as well as the velocity and temperature profiles for different values of the governing parameters are analyzed and discussed. Findings It is found that dual solutions exist for a certain range of the mixed convection parameter where its critical values decrease with the increasing of the copper (Cu) nanoparticle volume fractions and for the smaller needle size. It is also observed that the increasing of the copper (Cu) nanoparticle volume fractions and the decreasing of the needle size tend to enhance the skin friction coefficient and the local Nusselt number on the needle surface. A temporal stability analysis is performed to determine the stability of the dual solutions in the long run, and it is revealed that only one of them is stable, while the other is unstable. Originality/value The problem of hybrid nanofluid flow and heat transfer past a vertical thin needle with prescribed surface heat flux is the important originality of the present study where the dual solutions for the opposing flow are obtained.

Influence of Space-Varying Surface Heat Flux on the Heat Transfer Due to a Moving Fluid Over a Moving Surface

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Swati Mukhopadhyay ◽  
Iswar Chandra Mondal ◽  
Kuppalapalle Vajravelu ◽  
Robert A. Van Gorder
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Flux ◽  
Power Law ◽  
Surface Heat Flux ◽  
Flat Surface ◽  
Similarity Solutions ◽  
Surface Heat ◽  
Forced Convective Heat Transfer ◽  
Moving Fluid

Boundary-layer forced convective heat transfer at a moving flat surface parallel to a moving stream is presented for the case where the plate is subjected to a variable heat flux. In particular, we assume that the surface heat flux varies with spatial variable x according to a power-law rule. The similarity solutions for the problem are obtained by solving the reduced ordinary differential equations numerically, while exact solutions are provided for certain parametric values. It is noted that even in the case of prescribed surface heat flux, dual solutions exist when the surface and the fluid move in opposite directions.

Hybrid nanofluid flow on a shrinking cylinder with prescribed surface heat flux

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Iskandar Waini ◽  
Anuar Ishak ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Stagnation Point ◽  
Surface Heat Flux ◽  
Temporal Stability ◽  
Surface Heat ◽  
Physical Parameters ◽  
Hybrid Nanofluid ◽  
Content Type ◽  
Long Run

Purpose This study aims to investigate the flow impinging on a stagnation point of a shrinking cylinder subjected to prescribed surface heat flux in Al2O3-Cu/water hybrid nanofluid. Design/methodology/approach Using similarity variables, the similarity equations are obtained and then solved using bvp4c in MATLAB. The effects of several physical parameters on the skin friction and heat transfer rate, as well as the velocity and temperature profiles are analysed and discussed. Findings The outcomes show that dual solutions are possible for the shrinking case, in the range λc<λ<−1, where λc is the bifurcation point of the solutions. Meanwhile, the solution is unique for λ≥−1. Besides, the boundary layer is detached on the surface at λc, where the value of λc is affected by the hybrid nanoparticle φhnf and the curvature parameter γ. Moreover, the friction and the heat transfer on the surface increase with the rising values φhnf and γ. Finally, the temporal stability analysis shows that the first solution is stable in the long run, whereas the second solution is not. Originality/value The present work considers the problem of stagnation point flow impinging on a shrinking cylinder containing Al2O3-Cu/water hybrid nanofluid, with prescribed surface heat flux. This paper shows that two solutions are obtained for the shrinking case. Further analysis shows that only one of the solutions is stable as time evolves.

scholarly journals Wall-Jet Turbulent Boundary Layer Heat Flux, Velocity, and Temperature Spectra and Time Scales

1996 ◽  
Author(s):  
David G. Holmberg ◽  
David J. Pestian
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Velocity Field ◽  
Turbulent Boundary Layer ◽  
Flat Plate ◽  
Surface Heat Flux ◽  
Free Stream ◽  
Surface Heat ◽  
Wall Jet ◽  
Time Resolved

The interactions of boundary layer flow temperature fluctuations (t′) and velocity fluctuations (u′, v′) together with surface heat flux fluctuations (q′) have been investigated experimentally in a flat plate turbulent boundary layer in order to better understand time-resolved interactions between flow unsteadiness and surface heat flux. A Heat Flux Microsensor (HFM) was placed on a heated flat plate beneath a turbulent wall jet, and a split-film boundary layer probe was traversed above it together with a cold-wire temperature probe. The recorded simultaneous time-resolved u′v′t′q′ data can be correlated across the boundary layer. Results indicate that wall heat transfer (both mean and fluctuating components) is controlled by the u′ fluctuating velocity field. In the presence of high free-stream turbulence (FST), the heat flux is largely controlled by free stream eddies of large size and energy reaching deep into the boundary layer, such that heat flux spectra can be determined from the free-stream velocity field. This is evidenced by uq coherence present across the boundary layer, as well as by similarity in heat flux and u velocity spectra, and by the presence of large velocity scales down to the nearest wall measuring location just above the laminar sublayer.

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