查看更多>>摘要：This special issue encompasses the experimental and theoretical investigations on transport phenomena of nanofluids in cavities。 The contributions are classified as follows: (1) nanofluid flow in square/rectangular cavities， (2) nanofluid flow in cavities with obstacles， (3) nanofluid flow in wavy enclosures， (4) nanofluid flow in trapezoidal/circular/annular cavities， and (5) nanofluid flow in enclosures。
查看更多>>摘要：Combined effects of using inclined partition and magnetic field on the cooling performance of double slot jet impingement are analyzed with finite element method。 Two different shear thinning nanofluids are used while experimental data is available for the rheological properties。 Different values of of Reynolds number (Re between 100 and 1000)， velocity ratio (VR， between 0。2 and 1)， opening ratio (OR， between 0。05 and 0。95)， magnetic field strength (Ha， between 0 and 30) and inclination of partition (f2， between 0 and 40) are used。 It is observed that varying VR of the jets， size/inclination of the partition， magnetic field strength and nanfluid type， can be used to control the local and average convective heat transfer and cooling performance features effectively。 The average Nusselt number (Nu) rises with higher VR while at the highest VR the amount of increments are 23。5% and 28。5% with first (NFl) and second (NF2) nanofluid (NF)。 When magnetic field is imposed， effects of OR becomes important with NF1 at the lowest strength of magnetic field。 Average Nu reduces with higher magnetic field strength for NF1 while 14。4% reduction for the highest strength at OR = 0。95 is achieved。 However， for NF2 the trend is opposite and 18。8% increment is obtained。 Variations in the average Nu becomes 7。6% and 1。8% for NFl and NF2 when inclination of the partition is changed。 The cooling performance is estimated by using a feed-forward network modeling approach in terms of average Nu for NFl and NF2 by using 25 neuron in the hidden layer。
查看更多>>摘要：The heating or cooling performance of convective thermal systems is critically dependent upon their geometrical shapes/configurations apart from other controlling aspects。 Here， an effort is made to address the shape impact on thermal performance， using square and circular systems under the classical differentially heating configuration。 The comparison of systems' performance is made by applying the constraints of identical fluid volume， heating and cooling surfaces， and cavity inclinations for both systems。 The study covers mostly used practical working fluids namely air， water， and a water-based nanofluid。 For such a type of thermal system analysis， the numerical approach is chosen appropriately to generate a huge volume of the solved results。 The Prandtl number， Rayleigh number， the nanofluid concentration， and cavity orientation are used as the system parameters， and the study reveals a strong impact of the cavities' shapes。 In general， the thermal performance and evolved circulation (due to the differential heating) are found superior with the circular cavity over its equivalent square cavity configuration。 The analysis confirms that the geometric modification is a better choice for achieving superior heat transfer; the heat transfer enhancement could be up to similar to 22。21% (when the cavity is horizontal)， 24。11% (with inclined cavity) with air as a working medium。 There is a further enhancement on heat transfer with the modified circular cavity up to 2。76% (with horizontal cavity)， 15。19% (with inclined cavity) using nanofluid。 The heat flow dynamics from the heating side to the cooling side are also explored using the Bejan's heatlines。 The outcome of this study will help the designer to model the thermal device considering various controlling aspects from an appropriate thermal management point of view。
Ali, I. R.Alsabery, A. I.Mohamad, M.Kamardan, M. G....
15页
查看更多>>摘要：Mixed convection in a rectangular double lid-driven cavity filled with hybrid nanofluid (Al2O3-Cu-water) subjected to insulated sidewalls and sinusoidal temperature on horizontal walls is numerically investigated。 Using the SIMPLE algorithm for pressure， velocity coupling， the momentum， mass conservation， and energy equations are numerically solved by the finite-volume method (FVM)。 The data were validated by comparing the present results with the results of the problem solved by Sarris et al。 (Numer Heat Transf Part A Appl 42(5):513-530， 2010) for pure liquid。 The effects of amplitude ratio， phase deviation， and Reynolds numbers on the flow and heat transfer characteristics are discussed。 It is found that the rate of heat transfer is improved as the volume fraction of the hybrid nanoparticles and the amplitude ratio are increased。 The non-uniform heating at cavity walls tend to provide higher heat transfer rate and the heat transfer rate increases with respect to Reynolds number。
查看更多>>摘要：This paper reports the numerical study of magnetohydrodynamic radiative-convective flow in a square cavity containing a porous medium with Hall currents。 This study is relent to hydromagnetic fuel cell design and thermofluidic dynamics of complex magnetic liquid fabrication in enclosures。 The governing equations of this fluid system are solved by a finite-difference vorticity stream function approach executed in MATLAB software。 A detailed parametric investigation of the impact of Rayleigh number (thermal buoyancy parameter)， Hartman number (magnetic body force parameter)， Darcy number (permeability parameter)， Hall parameter and radiation parameter on the streamline， temperature contours， local Nusselt number along the hot wall and mid-section velocity profiles is computed。 Validation with previous special cases in the literature is included。 Hall current and radiative effects are found to significantly modify thermofluidic characteristics。 From the numerical results， it is found that the magnetic field suppresses the natural convection only for small buoyancy ratios。 But， for larger buoyancy ratio， the magnetic field is effective in suppressing the thermal convective flow。
查看更多>>摘要：In this manuscript， phase change material (PCM) including the nanoparticles is considered in a 3D cubic enclosure to investigate the mixed convection of heat transfer under the magnetic field effect。 Double rotating cylinders also are located in the middle of the enclosure to study the effect of their angular velocity in different conditions。 Governing equations are solved by Galerkin Finite Element Method (GFEM) and were confirmed by previous studies。 As main outcomes， results with enhanced angular velocity， both the average temperature and cumulative energy were significantly decreased。 Furthermore， unaltered fluidity (Ha = 0) imposes greater entropy， but this tendency reverses when the Hartman number (Ha) rises， resulting in minimum entropy trends。
查看更多>>摘要：Immiscible flow has been extensively emerged in science and technology。 Researchers and architects were delighted by the concept of multiple fluid transport by the means of shear pressure。 The reliance of drag impact of the two immiscible liquids is very much aspired but yet challenging。 A mathematical examination has been conveyed to understand the free convection inside a vertical vessel。 There are two immiscible liquids filled in the enclosure which are synthesized as two discrete regions encompassing a nanofluid and permeable fluid。 The Tiwari-Das model and Dupuit-Forchheimer is utilized to define the nanofluid and permeable fluid， respectively。 Southwell over-relaxation technique subject to suitable interface and boundary conditions is bestowed to solve the conservation equations。 Essential criteria defining the fluid flow and energy transfer are studied deliberately。 The outcomes demonstrate that the Grashof， Brinkman and Darcy numbers augment the velocity， whereas inertial， solid volume fraction， viscosity and thermal conductivity ratios depletes the momentum。 The temperature distributions are not much modulated with any of the controlling parameters。 By sagging nanoparticles， the flow is not much reformed but reckoning copper nanoparticle as ethylene glycol-mineral oil base fluid regulates the supreme flow。 Diamond nanoparticle dropped in water catalyzes the highest rate of heat transfer。
Abdulsahib, Ahmed DhaferHashim, Atheer SaadAl-Farhany, KhaledAbdulkadhim, Ammar...
17页
查看更多>>摘要：The current article presents a numerical simulation of the nanofluid convection inside a square enclosure with two inner adiabatic circular bodies。 Galerkin finite-element analysis was utilized to solve the governing equations under the assumptions of laminar， steady flow conditions considering a homogeneous single-phase approach。 The parameters under investigation are Rayleigh number (Ra)， solid volume fraction， the horizontal position of the two inner cylinders， and the inclination angle of the enclosure。 The results indicate that increasing the Rayleigh number， and the solid volume fraction improves the heat transport rate。 It is obtained that at low Ra， there is no significant impact on the enclosure angle， while as the Ra goes up， the heat transfer rate increases gradually。 In addition， the best location of the internal bodies is in the middle of the cavity as it exhibits an increase in the flow velocity。 To obtain the highest Nusselt number， it is recommended to use an inclination angle of 30 at any value of the Rayleigh number。
查看更多>>摘要：In the present paper， numerical investigations of the magnetohydrodynamics forced convection of CNT-water nanofluid inside a square enclosure with one inlet and one outlet were performed。 The analysis was carried out for a wide range of Reynolds number (100 <= Re <= 1000)， Hartmann number (0 <= Ha <= 60)， inclination angle of the magnetic field (0 degrees <= gamma <= 90 degrees)， elasticity of the bottom and left walls of the enclosure (10(4) <= E <= 10(7))， location of the center of the hexagonal body in horizontal directions (0。3 <= x(0)/L <= 0。7) and in normal directions (0。25 <= y(0)/L <= 0。75)， size of the internal hexagonal body (0。1 <= a/L <= 0。3)， and， finally， the volume fraction of the nanoparticles (phi = 0 and 0。1)。 For the flexible walls of the enclosure， a series of coupled fluid-structure interaction (FSI) analyses were accomplished by utilizing the Arbitrary Lagrangian-Eulerian formulation。 It has been revealed that the bottom wall of the enclosure is very sensitive to the elastic wall， while the Nusselt number on the top wall increases with Hartmann number no matter which wall is elastic。 It is also the most contributor to the heat transfer at Reynolds numbers of Re = 100 and 500， while the contribution of other walls changes with Reynolds number。
查看更多>>摘要：The purpose of the current article is to evaluate the impact of coupled buoyancy and thermocapillary driven convection in a cylindrical porous annulus saturated with Ag/MgO-water hybrid nanofluid along with viscous dissipation effects。 The left side wall of the annulus is kept heated， while the right side wall of the annulus is kept cold。 The top and bottom limits are supposed to be adiabatic。 A thin circular baffle is anchored to the inner cylinder。 The primary goal of this research is to look into the effect of baffle size and location on Marangoni convection， thermal behaviour， and flow fields。 Here， the effects of viscous dissipation are taken into account。 The governing equations are subjected to the finite difference approach， which employs the ADI， SOR， and central differencing schemes。 In this work， contour plots and average Nusselt number profiles are used to demonstrate the flow type， temperature behaviour， and thermal variations along the enclosure。 The research demonstrates that the size and location of the fin plays a prominent role in influencing fluid flow within the annulus。 An improvement in thermal transfer rate is reported for phi and for the higher value of Ma considering the viscous dissipation， length and location of the baffle。
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Springer Nature