Numerical validation of aκ-ω-κθ-ωθheat transfer turbulence model for heavy liquid metals

Abstract. Computational Fluid Dynamics codes are used in many industrial applications in order to evaluate interesting physical quantities, such as the heat transfer in turbulent flows. Commercial CFD codes use only turbulence models with an imposed constant turbulent Prandtl number P r t , which can give accurate results only for simulations when a strong similarity between the velocity field and the temperature field can be assumed. For fluids with a low Prandtl number, as for heavy liquid metals, a constant turbulent Prandtl number leads to an overestimation of the heat transfer, so experimental results and Direct Numerical Simulation cannot be reproduced. In this work we propose a new k-Ω-k θ -Ω θ turbulence model as an improvement of the k-ω-k θ -ω θ turbulence model, already validated by the authors, where Ω and Ω θ are calculated as the natural logarithm of the variables ω and ω θ . With this reformulation of the previous turbulence model we obtain some important advantages in numerical stability and robustness of the code. Results for the simulations of fully developed turbulent flows in two and three dimensional geometries are reported and compared with experimental correlations and DNS data, when available.

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“…This keeps the accuracy of the results and enhances the algorithm stability [6]. The new system of equations is…”

Section: Transport Equations and Turbulence Modelsmentioning

confidence: 97%

“…We briefly recall the RANS equations and the first formulation of a four parameter k-ε-k θ -ε θ , then we derive the k-ω formulation already validated by the authors [6,7,8,9]. Finally the new logarithmic k-Ω-k θ -Ω θ model is presented.…”

Section: Introductionmentioning

confidence: 99%

Numerical Validation of a Four Parameter Logarithmic Turbulence Model

Cerroni¹,

Vià²,

Manservisi³

et al. 2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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“…We implement and solve the system (17)(18)(19)(20) together with the Navier-Stokes equations (8-9-13) in an in-house parallel finite element code. We employ Taylor-Hood finite elements for the system of Navier-Stokes in order to satisfy the inf-sup condition and this system is solved with a standard projection method.…”

Section: Propertymentioning

confidence: 99%

“…This type of models have been already studied by some authors for forced convection and buoyant flows and should be more reliable in complex geometrical configurations [7,8,[14][15][16][17][18][19]. In particular, in [8,[17][18][19], a four parameter turbulence model for liquid metal flows has been developed and validated in several geometries. To extend this work we present a logarithmic k-Ω-k θ -Ω θ formulation of the four parameter turbulence model to improve its numerical robustness and the implementation of the boundary conditions as explained in [20].…”

Section: Introductionmentioning

confidence: 99%

A Logarithmic Turbulent Heat Transfer Model in Applications with Liquid Metals for PR = 0.01-0.025

Vià¹,

Manservisi²,

Giovacchini³

2020

Preprint

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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 not valid 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 or four parameter turbulence models. In this work we assess a four parameter logarithmic turbulence model for liquid metals based on RANS approach. Several simulation results considering fluids with Pr = 0.01 and Pr = 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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“…For details on the benefits of a logarithmic turbulence model and on the formulation of the eddy viscosity and eddy thermal diffusivity on can refer to [6], [7], [8], [9] and [10]. In the present turbulence model we adopt a realizability constrain where the eddy viscosity is limited from above by a value that depends on the local values of the mean strain rate tensor modulus and of the turbulent kinetic energy k [11], [12].…”

Section: Numerical Modellingmentioning

confidence: 99%

A multiscale numerical algorithm for heat transfer simulation between multidimensional CFD and monodimensional system codes

Chierici

Chirco

Vià

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. Nowadays the rapidly-increasing computational power allows scientists and engineers to perform numerical simulations of complex systems that can involve many scales and several different physical phenomena. In order to perform such simulations, two main strategies can be adopted: one may develop a new numerical code where all the physical phenomena of interest are modelled or one may couple existing validated codes. With the latter option, the creation of a huge and complex numerical code is avoided but efficient methods for data exchange are required since the performance of the simulation is highly influenced by its coupling techniques. In this work we propose a new algorithm that can be used for volume and/or boundary coupling purposes for both multiscale and multiphysics numerical simulations. The proposed algorithm is used for a multiscale simulation involving several CFD domains and monodimensional loops. We adopt the overlapping domain strategy, so the entire flow domain is simulated with the system code. We correct the system code solution by matching averaged inlet and outlet fields located at the boundaries of the CFD domains that overlap parts of the monodimensional loop. In particular we correct pressure losses and enthalpy values with source-sink terms that are imposed in the system code equations. The 1D-CFD coupling is a defective one since the CFD code requires point-wise values on the coupling interfaces and the system code provides only averaged quantities. In particular we impose, as inlet boundary conditions for the CFD domains, the mass flux and the mean enthalpy that are calculated by the system code. With this method the mass balance is preserved at every time step of the simulation. The coupling between consecutive CFD domains is not a defective one since with the proposed algorithm we can interpolate the field solutions on the boundary interfaces. We use the MED data structure as the base structure where all the field operations are performed, allowing the algorithm to be used with all the numerical codes where a MED duplicate of the field solution can be created. The MEDmem libraries come with the Salome platform and include basic methods for handling meshes and fields. We provide results that show the consistency of the proposed algorithm.

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Numerical validation of aκ-ω-κ_θ-ω_θheat transfer turbulence model for heavy liquid metals

Cited by 8 publications

References 14 publications

Numerical Validation of a Four Parameter Logarithmic Turbulence Model

Numerical Validation of a Four Parameter Logarithmic Turbulence Model

A Logarithmic Turbulent Heat Transfer Model in Applications with Liquid Metals for PR = 0.01-0.025

A multiscale numerical algorithm for heat transfer simulation between multidimensional CFD and monodimensional system codes

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