Multifield Approach and Interface Locating Method for Two-Phase Flows in Nuclear Power Plant

Mimouni, S.; Denefle, R.; Fleau, Solène; Vincent, Stéphane

doi:10.1007/978-981-287-615-7_33

Cited by 4 publications

(4 citation statements)

References 18 publications

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“…Thus, a new drag force expression has been developed to deal with large interfaces within the MFA. Details can be found in [29,47]. The modeling of large interfaces and surface tension forces with the Ishii model is based on a volumetric formulation [27,29,48] taken from [37].…”

Section: Multi-field Approach (Mfa) 231 a Two-velocity Model For Twmentioning

confidence: 99%

A priori filtering and LES modeling of turbulent two-phase flows application to phase separation

et al. 2018

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The Large Eddy Simulation (LES) of two-phase flows with resolved scale interfaces is investigated through the a priori filtering of Direct Numerical Simulations (DNS) of one-fluid and multifield models. A phase inversion benchmark [1][2][3][4] is considered highlighting many coalescence and interface rupture events in a kind of atomization process. The order of magnitude of specific two-phase subgrid LES terms is first considered with the two modeling approaches. Then, different existing models such as Smagorinsky [5], Wall-Adapting Local Eddyviscosity (WALE) model [6], Bardina [7], Mixed [8] and Approximate Deconvolution Model (ADM) [9] are used to account for two-phase subgrid effects. These models are compared to filtered DNS results. The main conclusion concerning a priori LES filtering is that the inertia term is not predominant in two-phase flows with fragmentation and rupture of interface. This conclusion is different from that of the studies of [3,[10][11][12][13]. concerning LES models, functional modeling do 1 not correlate to filtered DNS results whereas structural approaches do. Bardina and ADM are clearly the good LES framework to consider for two-phase flows with resolved scale interfaces. ADM is clearly better than Bardina in our study. The authors greatly acknowledge the reviewer for its comments and remarks that have guided us in improving the technical and editorial aspects of the manuscript. From a general point of view, all the comments and remarks recommended by the reviewer have been taken into account. They are highlighted in the text in red. More specifically, we can detail them as follows: COMPUTERS & FLUIDS 1) I would recommend to add the main conclusions to the abstract and to add a separate section conclusions to the paper.In agreement with reviewer remark and in order to improve the fast reading and understanding of the paper, we have included a conclusion part in the abstract. In addition, the last section have been extended to "Summary, conclusion and future work", with addition of conclusions in order to highlight the originality and main results of the work. 2) Abstract : DNS and ADM should be defined.Done. The same has been achieved for the Wall-Adapting Local Eddy-viscosity (WALE) model. 3) A streak of the interface points towards the upper left corner of the box. Is that physical?Yes, this a physical feature of the interface. As we are dealing with liquid-liquid twophase flows, when the light fluid (blue surface) goes to the top part of the cavity under gravity effects, heavy liquid can be trapped near vertical walls or vertical corners, inducing this king of interface topology.4) The sentence "Among the few existing …" seems to have a grammar mistake. Detailed Response to ReviewersThis sentence has been rewritten as follows "Among the few existing references, it is worth mentioning the work on LES formulation for the one-fluid model and subsequent a priori LES filtering of DNS simulations for the estimate of new specific two-phase contributions in the mass, momentu...

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Section: Multi-field Approach (Mfa) 231 a Two-velocity Model For Twmentioning

confidence: 99%

A priori filtering and LES modeling of turbulent two-phase flows application to phase separation

et al. 2018

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“…A bubble with a diameter inferior to 8x will present indeed, because of the CSF scheme for the curvature calculation, an overlap of the information used to calculate the curvature at two opposite points of the interface. More precisely, the dispersed gas field creation is activated where (Mimouni, 2014):…”

Section: Three Field Modelmentioning

confidence: 99%

CFD calculations of flow pattern maps and LES of multiphase flows

Mimouni

Fleau

Vincent

2017

Nuclear Engineering and Design

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Boiling crisis and flows occurring in a steam generator or a heat exchanger remain a major limiting phenomenon for the analysis of operation and safety of both nuclear reactors and conventional thermal power systems. Firstly, the choice is made to investigate a hybrid modeling of the flow, considering the gas phase as two separated fields, each one being modeled with different closure laws. In so doing, the small and spherical bubbles are modeled through a dispersed approach within the two-fluid model, and the distorted or large bubbles are simulated with an interface locating method. This kind of approach is requiring a set of mass transfer terms between the continuous and the dispersed fields of the same physicochemical phase. The main outcome is the simulation of three field cases with a complete set of coupling terms between the two gas fields. Firstly, validation results are presented in the Castillejos test case where air is injected at the bottom of a cylindrical bubble column. Next, METERO experiments are simulated with this multifield approach. METERO is an experimental rig dedicated to the study of turbulent mixing of air and water in horizontal flows. The different regimes encountered in the METERO experiments, i.e. stratified flows, slug flows, plug flows, stratified dispersed bubbly flows and dispersed bubbly flows are simulated and presented in the paper. Finally, MAXI2 experiment (liquid/vapour flow in oblique tubes bundle geometry) is simulated: the three-field approach gives a reasonable agreement with experimental data whereas the standard two-field approach (dedicated to dispersed bubbly flow) fails. The important topic of turbulence modelling for two-phase flows is also addressed in the paper. The key point is that standard LES models may fails in the simulation of large interfaces. But the ADM model could constitute an interesting alternative in further studies.

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“…This method was initially developed to represent dispersed flows [14]. Over the past decade, multi-scale extension has developed, to expand the flow regimes that can be modeled within the Euler-Euler framework [15][16][17][18][19]: in the present study, this last approach was employed, through the NEPTUNE_CFD 6.1 software. The simulations performed in this study relied on a two-field approach, with one field for the vapor phase, and another field for the liquid.…”

Section: Introductionmentioning

confidence: 99%

Euler–Euler Multi-Scale Simulations of Internal Boiling Flow with Conjugated Heat Transfer

2023

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A numerical approach was implemented, to study a boiling flow in a horizontal serpentine tube. A NEPTUNE_CFD two-fluid model was used, to study the behavior of the refrigerant R141b in diabatic cases. The model was based on the Euler–Euler formalism of the Navier–Stokes equations, in which governing equations are solved for both phases of the fluid at each time step. The conjugate heat transfer—between the tube wall and the fluid—was considered via a coupling with the SYRTHES 4.3 software, which solves solid conduction in three dimensions. A mesh convergence study was carried out, which found that a resolution of 40 meshes per diameter was necessary for our case. The approach was validated by comparison with an experimental study of the literature, based on the faithful reproduction of the positions of two-phase flow regime transitions in the domain. Original post-processing was used, to unravel the flow characteristics. The mean and RMS fields of void fraction, temperatures and stream wise velocities in several sections were analyzed, when statistical convergence was reached. A thermal equilibrium was reached in the saturated liquid, but not in the vapor phase, due to the flow dynamic and possibly the presence of droplets. Finally, a thermal analysis of the configuration was proposed. It demonstrated the strong coupling between the temperature distribution in the solid, and the two-phase flow regimes at stake in the fluid domain.

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Multifield Approach and Interface Locating Method for Two-Phase Flows in Nuclear Power Plant

Cited by 4 publications

References 18 publications

A priori filtering and LES modeling of turbulent two-phase flows application to phase separation

A priori filtering and LES modeling of turbulent two-phase flows application to phase separation

CFD calculations of flow pattern maps and LES of multiphase flows

Euler–Euler Multi-Scale Simulations of Internal Boiling Flow with Conjugated Heat Transfer

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