Statistics of Heat Transfer in Two-Dimensional Turbulent Rayleigh-Bénard Convection at Various Prandtl Number

Yang, Hui; Wei, Yikun; Zhu, Zuchao; Yue, Qian

doi:10.3390/e20080582

Cited by 9 publications

(7 citation statements)

References 39 publications

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“…The flow structure for the highest value of the magnetic field presents a model picture of turbulence-with high velocity vectors, thermal plumes meandering on the active surfaces and dissipating as a result of the intensity of the flow. This obtained flow field is almost identical to the results presented in [46] for Prandtl number 100 and Ra = 5.4 × 10 9 (Prandtl number in ∆T = 11 • C is equal to 98.7 and Ra TM = 1.12 × 10 9 ). Therefore, it can be concluded that the strong magnetic field applied to the paramagnetic fluid can accelerate the full turbulence formation in comparison to free convection without changing the thermal conditions of the system.…”

Section: Velocitiessupporting

confidence: 87%

An Analysis of a Laminar-Turbulent Transition and Thermal Plumes Behavior in a Paramagnetic Fluid Subjected to an External Magnetic Field

Kraszewska

Donizak

2021

Energies

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Transition to turbulence and changes in the fluid flow structure are subjects of continuous analysis and research, especially for unique fields of research such as the thermo-magnetic convection of weakly magnetic fluids. Therefore, an experimental and numerical research of the influence of an external magnetic field on a natural convection’s fluid flow was conducted in the presented research. The experimental part was performed for an enclosure with a 0.5 aspect ratio, which was filled with a paramagnetic fluid and placed in a superconducting magnet in a position granting the enhancement of the flow. The process was recorded as temperature signals from the thermocouples placed in the analyzed fluid. The numerical research enabled an investigation based not only on temperature, but velocities as well. Experimental and numerical data were analyzed with the application of extended fast Fourier transform and wavelet analysis. The obtained results allowed the determination of changes in the nature of the flow and visualization of the influence of an imposed strong magnetic field on a magnetic fluid. It is proved that an applied magnetic field actuates the flow in Rayleigh-Benard convection and causes the change from laminar to turbulent flow for fairly low magnetic field inductions (2T and 3T for ΔT = 5 and 11 °C respectively). Fast Fourier transform allowed the definition of characteristic frequencies for oscillatory states in the flow, as well as an observation that the high values of magnetic field elongate the inertial range of the flow on the power spectrum density. Temperature maps obtained during numerical simulations granted visualizations of thermal plume formation and behavior with increasing magnetic field.

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Section: Velocitiessupporting

confidence: 87%

An Analysis of a Laminar-Turbulent Transition and Thermal Plumes Behavior in a Paramagnetic Fluid Subjected to an External Magnetic Field

Kraszewska

Donizak

2021

Energies

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“…The Rayleigh–Taylor instability is a well-known and widely studied gravity-driven effect occurring when a layer of a heavier fluid lies on top of another layer of a lighter fluid [ 38 , 39 , 40 ]. Perturbation at the interface between the two fluids causes the heavier one to penetrate the lighter fluid.…”

Section: Numerical Applicationsmentioning

confidence: 99%

Lattice Boltzmann Solver for Multiphase Flows: Application to High Weber and Reynolds Numbers

Hosseini

Safari

Thévenin

2021

Entropy

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The lattice Boltzmann method, now widely used for a variety of applications, has also been extended to model multiphase flows through different formulations. While already applied to many different configurations in low Weber and Reynolds number regimes, applications to higher Weber/Reynolds numbers or larger density/viscosity ratios are still the topic of active research. In this study, through a combination of a decoupled phase-field formulation—the conservative Allen–Cahn equation—and a cumulant-based collision operator for a low-Mach pressure-based flow solver, we present an algorithm that can be used for higher Reynolds/Weber numbers. The algorithm was validated through a variety of test cases, starting with the Rayleigh–Taylor instability in both 2D and 3D, followed by the impact of a droplet on a liquid sheet. In all simulations, the solver correctly captured the flow dynamics andmatched reference results very well. As the final test case, the solver was used to model droplet splashing on a thin liquid sheet in 3D with a density ratio of 1000 and kinematic viscosity ratio of 15, matching the water/air system at We = 8000 and Re = 1000. Results showed that the solver correctly captured the fingering instabilities at the crown rim and their subsequent breakup, in agreement with experimental and numerical observations reported in the literature.

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“…Some related work can be seen in references [ 34 , 35 , 36 , 37 , 38 ]. Yikun Wei et al [ 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ] investigated thermal behavior, heat transfer, and entropy using the Lattice Boltzmann Method and also a numerical approach.…”

Section: Introductionmentioning

confidence: 99%

Hall and Ion-Slip Effect on CNTS Nanofluid over a Porous Extending Surface through Heat Generation and Absorption

Ameen

Shah

Islam

et al. 2019

Entropy

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In this research work, a 3D rotating flow of carbon nanotubes (CNTs) over a porous stretchable sheet for heat and mass transfer is investigated. Kerosene oil is considered as a base liquid and two types of CNTs, (Single & Multi) WCNTs are added as the additives to the base liquid. The present analysis further comprises the combined effect of the Hall, ion-slip, and thermal radiation, along with heat generation/absorption. The appropriate ordinary differential system of equations after applying appropriate transformation is calculated. The resulting nonlinear system of equations (conservation of mass, momentum, temperature) is explained by HAM (Homotopy Analysis Method). Solution of velocities and thermal fields are obtained and discussed graphically. Expression of C f and N u are intended for both type of nanoliquids. The influences of prominent physical factors are plotted for velocities and thermal profiles using Methematica. These graphical results are qualitatively in excellent agreement with the previous published results. Also, single wall nanoparticles are found to have higher temperatures than multi wall CNTs nanoparticles.

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Statistics of Heat Transfer in Two-Dimensional Turbulent Rayleigh-Bénard Convection at Various Prandtl Number

Cited by 9 publications

References 39 publications

An Analysis of a Laminar-Turbulent Transition and Thermal Plumes Behavior in a Paramagnetic Fluid Subjected to an External Magnetic Field

An Analysis of a Laminar-Turbulent Transition and Thermal Plumes Behavior in a Paramagnetic Fluid Subjected to an External Magnetic Field

Lattice Boltzmann Solver for Multiphase Flows: Application to High Weber and Reynolds Numbers

Hall and Ion-Slip Effect on CNTS Nanofluid over a Porous Extending Surface through Heat Generation and Absorption

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