Numerical simulation of forced and mixed convection turbulent liquid sodium flow over a vertical backward facing step with a four parameter turbulence model

Vià, Roberto Da; Manservisi, Sandro

doi:10.1016/j.ijheatmasstransfer.2019.01.129

Cited by 18 publications

(12 citation statements)

References 23 publications

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“…In [11], an anisotropic three-equation turbulence model has been proposed and applied to this configuration in forced and mixed convection regimes showing a promising potential for the prediction of the turbulent heat flux. In [16], RANS simulations have been performed with an isotropic four-parameter turbulence model (4P) in forced and mixed convection regimes considering a linear expression for the Reynolds stress tensor and the turbulent heat flux. Results are promising in both regimes but the adoption of the anisotropic formulation that we are proposing could improve the prediction of the turbulent heat flux components.…”

Section: Backward Facing Step Geometrymentioning

confidence: 99%

“…In [11], the thermal model has been coupled with a low-Reynolds linear k-ε model, while in [12], the coupling with a second-order Reynolds stress model has shown better results. In [13][14][15][16], an isotropic four-parameter model has been proposed. The model introduces two additional thermal transport equations for the evaluation of the squared temperature fluctuations k θ and its dissipation ε θ .…”

Section: Introductionmentioning

confidence: 99%

“…Both configurations have been tested with the isotropic four-parameter turbulence model. Plane channel simulations for several Re τ and Pr = 0.01, 0.025 have been successfully performed [13,14,16]. Numerical simulations in forced and mixed convection regimes are very promising for the backward-facing step configuration [15], however the adoption of an anisotropic formulation is required to improve the prediction of turbulent heat flux components.…”

Section: Introductionmentioning

confidence: 99%

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A New Anisotropic Four-Parameter Turbulence Model for Low Prandtl Number Fluids

Barbi

Giovacchini

Manservisi

2021

Fluids

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Due to their interesting thermal properties, liquid metals are widely studied for heat transfer applications where large heat fluxes occur. In the framework of the Reynolds-Averaged Navier–Stokes (RANS) approach, the Simple Gradient Diffusion Hypothesis (SGDH) and the Reynolds Analogy are almost universally invoked for the closure of the turbulent heat flux. Even though these assumptions can represent a reasonable compromise in a wide range of applications, they are not reliable when considering low Prandtl number fluids and/or buoyant flows. More advanced closure models for the turbulent heat flux are required to improve the accuracy of the RANS models dealing with low Prandtl number fluids. In this work, we propose an anisotropic four-parameter turbulence model. The closure of the Reynolds stress tensor and turbulent heat flux is gained through nonlinear models. Particular attention is given to the modeling of dynamical and thermal time scales. Numerical simulations of low Prandtl number fluids have been performed over the plane channel and backward-facing step configurations.

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Section: Backward Facing Step Geometrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A New Anisotropic Four-Parameter Turbulence Model for Low Prandtl Number Fluids

Barbi

Giovacchini

Manservisi

2021

Fluids

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“…As a consequence of the change of state variables, some model coefficients had to be changed in order to improve the numerical stability, and the resulting models have been validated with simulations of plane channels and cylindrical ducts for Pr = 0.025. The model, in a fully logarithmic version and with additional terms accounting for buoyancy, has also been used to simulate a sodium turbulent flow over a backward facing step geometry, with Pr = 0.0088, in the cases of forced and mixed convection [24]. Many studies have been performed to both examine the range of validity of the model and to improve its numerical stability.…”

Section: Introductionmentioning

confidence: 99%

A Logarithmic Turbulent Heat Transfer Model in Applications with Liquid Metals for Pr = 0.01–0.025

2020

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The study of turbulent heat transfer in liquid metal flows has gained interest because of applications in several industrial fields. The common assumption of similarity between the dynamical and thermal turbulence, namely, the Reynolds analogy, has been proven to be invalid for these fluids. Many methods have been proposed in order to overcome the difficulties encountered in a proper definition of the turbulent heat flux, such as global or local correlations for the turbulent Prandtl number and four parameter turbulence models. In this work we assess a four parameter logarithmic turbulence model for liquid metals based on the Reynolds Averaged Navier-Stokes (RAN) approach. Several simulation results considering fluids with P r = 0.01 and P r = 0.025 are reported in order to show the validity of this approach. The Kays turbulence model is also assessed and compared with integral heat transfer correlations for a wide range of Peclet numbers.

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“…In the past few decades, a lot of effort has been devoted to investigating the flow and heat transfer properties of liquid sodium (Schumm et al, 2016;Da Vià and Manservisi, 2019). A lot of work, including both experimental and numerical studies, has been carried out to provide information on heat transfer in liquid sodium.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Turbulent Heat Transfer Properties at Low Prandtl Number

et al. 2020

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The sodium-cooled fast reactor (SFR), which is one of the most promising candidates for meeting the goal declared by the Generation IV International Forum (GIF), has drawn a lot of attention. Turbulent heat transfer in liquid sodium, which is a low-Prandtl fluid, is an extremely complex phenomenon. The limitations of the commonly used eddy diffusivity approach have become more evident when considering low-Prandtl fluids. The current study focuses on the assessment and optimization of the existing modeling closure for single-phase turbulence in liquid sodium based on reference results provided by the LES method. In this study, a wall-resolved Large-Eddy Simulation was performed to simulate the flow and heat transfer properties in a turbulent channel at low Prandtl number. The simulation results were first compared with the DNS results obtained from the literature. A good agreement demonstrated the capability of the employed numerical approach to predict the turbulent and heat transfer properties in a low-Prandtl number fluid. Consequently, new reference results were obtained for the typical Prandtl number and wall heat flux of an SFR. A time-averaged process was employed to evaluate the temperature profile quantitatively as well as the turbulent heat flux. Their dependency was also evaluated based on a systematic CFD simulation that covers the typical Reynolds numbers of SFRs. Based on the reference results obtained, the coefficients employed in an algebraic turbulent heat flux model (AFM) are calibrated. The optimized coefficients provide more accurate prediction of heat transfer properties for typical flow conditions of an SFR than the existing models found in the literature.

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Numerical simulation of forced and mixed convection turbulent liquid sodium flow over a vertical backward facing step with a four parameter turbulence model

Cited by 18 publications

References 23 publications

A New Anisotropic Four-Parameter Turbulence Model for Low Prandtl Number Fluids

A New Anisotropic Four-Parameter Turbulence Model for Low Prandtl Number Fluids

A Logarithmic Turbulent Heat Transfer Model in Applications with Liquid Metals for Pr = 0.01–0.025

Numerical Investigation of Turbulent Heat Transfer Properties at Low Prandtl Number

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