# MONACO_2025: Modelling natural convection: A Challenge for the Full Digital 2025 Ambition

Remi Manceau

► To cite this version:

Remi Manceau. MONACO_2025: Modelling natural convection: A Challenge for the Full Digital 2025 Ambition. 17th ERCOFTAC SIG15/MONACO_2025 workshop: Turbulent natural convection flows in differentially heated cavities, Jan 2023, Pau, France. hal-03969991

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Submitted on 3 Sep 2024

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<figure><img src="image_1.png" /></figure>

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# MONACO_2025

## MOdelling NAtural CONvection:
A Challenge for the Full Digital 2025 Ambition

ANR Project ANR-17-CE06-0005-01
(01/03/2018-28/2/2023)

Coordinator:
Rémi Manceau (LMAP, CNRS-University of Pau-Inria)

<figure><img src="image_2.png" /></figure>

17th ERCOFTAC SIG15 / MONACO_2025 workshop

Turbulent natural convection flows in differentially heated cavities

19-20 January 2023, Pau, France
✓ **Road vehicles: underhood thermal management**

▷ CFD = routine tool for cruise regime (forced convection)

▷ Transient phases (stops): dominated by natural convection ⇒ CFD defective

▷ Dimensioning: costly wind-tunnel experiments using full size models

▷ Ambition fixed in 2015: full digital in 2025

✓ **Nuclear engineering**

▷ Importance of natural convection: thermal shocks, stratification, boiling, etc.

▷ Improvement of safety and extension of the lifespan of the power plants

▷ Design of future generations of power plants, including SMR

Very different industrial contexts / very close scientific issues
⇒ Numerical simulation of turbulent flows in natural convection
regime

✓ **Themes of the challenge *Clean, secure and efficient energy***:

▷ Desing of technologies with low environmental impact

▷ Prevention of risks linked to energy technologies
## LMAP

(Applied mathematics department)
University of Pau/CNRS/E2S
UPPA
Inria project-team CAGIRE

* ✓ Coordinator: Rémi Manceau

* ✓ Turbulence modelling

## Institute Pprime

CNRS/ENSMA/University of
Poitiers

* ✓ Project leader: Didier Saury

* ✓ Experiments

## PSA Group (now Stellantis)

R&D Vélizy

* ✓ Project leader: Vincent Herbert

* ✓ Simulation and experiments in industrial configurations

## EDF

R&D Chatou

* ✓ Project leader: Sofiane Benhamadouche

* ✓ Modelling and code development (Code_Saturne)
# Objectives

## ✓ Scientific objectives

* Progress in modelling of turbulence/buoyancy interactions

* Hybrid RANS/LES modelling: cost compatible with industrial needs

* Statistical approach (RANS) (low cost) where possible

* Fine-grained description of turbulence (LES) only where necessary

* New experimental database in cavity = unique database open to the community

## ✓ Technical objectives

* Propose a numerical methodology for dimensioning, operational reliability and safety

* Address regimes dominated by natural convection, which were not addressed numerically

* Decision-making tools in order to reach the appropriate methodology for the high-performance design of low-emission vehicle and power plants with a high level of safety
Work program

<figure><img src="image_3.png" /></figure>

✓ 1 PhD thesis supported by PSA

✓ 2 PhD theses supported by EDF

✓ 2 PhD theses and 18 months of post-doc supported by the ANR
<figure><img src="image_4.png" /><figcaption>Figure: Temperature variance at the wall: conjugate heat transfer</figcaption></figure>

* ✓ Dynamic second-moment closure (EB-RSM)

* ✓ Thermal second-moment closure (EB-DFM)

* ⇒ Extension to all possible boundary conditions

* ✓ Eddy-viscosity models (automotive industry)

* ✓ Issue of the sensitivity to buoyancy

* ⇒ Extension of the model (Boussinesq) to buoyancy

<figure><img src="image_5.png" /><figcaption>Figure: Velocity in a differentially heated infinite cavity</figcaption></figure>
# Summary of the results

<figure><img src="image_6.png" /><figcaption>Figure: Q contours in a periodic hill flow</figcaption></figure>

* ✓ Development of the HTLES hybrid RANS/LES model in Code_Saturne

* ✓ Improvement of the model (theory → practice)

* ✓ Convincing results for wall-bounded dynamics

* ✓ Encouraging for mechanical and thermal fatigue

* ✓ Extension of the HTLES approach to natural convection

* ✓ Problems at the RANS → LES transition
⇒ New model (elliptic shielding)

<figure><img src="image_7.png" /><figcaption>Figure: Q contours in a differentially-heated cavity</figcaption></figure>
Summary of the results

<figure><img src="image_8.png" /><figcaption>Figure: Cavity with a partially heated inner obstacle at Ra = 1.4 × 10⁹</figcaption></figure>

✓ Experimental configuration representative of the underhood of a vehicle

✓ PIV (mean and rms velocities) and thermocouples (temperature)

✓ Stationary and transient cases

✓ Identification of a complex physics (laminar/turbulent transition, high and low frequencies, complex recirculation patterns, flapping of the jet)

✓ Ongoing validation of models from RANS to LES
Publications (so far)

✓ 4 PhD theses:

Duffal, V. (2020). "Développement d'un modèle hybride RANS-LES pour l'étude des efforts installationnaires en paroi". PhD thesis. Université de Pau et des Pays de l'Adour.

Weppe, A. (2022). "Etude expérimentale d'écoulements turbulents à effets de flottabilité dominants en milieu confiné comportant un obstacle partiellement chauffé". PhD thesis. École Nationale Supérieure de Mécanique et d'Aérotechnique.

Mangeon, Gaëtan (Feb. 2020). "Second-moment closure of the turbulent heat fluxes for all type of thermal boundary conditions at the wall". Theses. Université de Pau et des Pays de l'Adour.

Jameel, Syed Mohd Saad (Dec. 2020). "Turbulence modelling of mixed and natural convection regimes in the context of the underhood-space of automobiles.". Theses. Université de Pau et des Pays de l'Adour.

✓ 4+1 articles:

Weppe, A., F. Moreau, and D. Saury (Sept. 2022). "Experimental investigation of a turbulent natural convection flow in a cubic cavity with an inner obstacle partially heated". In: *International Journal of Heat and Mass Transfer* 194, p. 123052.

Mangeon, Gaëtan, Sofiane Benhamadouche, Jean-François Wald, and Remi Manceau (Dec. 2020). "Extension to various thermal boundary conditions of the elliptic blending model for the turbulent heat flux and the temperature variance". In: *Journal of Fluid Mechanics* 905.A1, pp. 1–34.

Manceau, Remi (2019a). "Hybrid temporal LES: Development and applications". In: *ERCOFTAC Bulletin*. Progress in RANS-based Scale-Resolving Flow Simulation Methods 120, pp. 38–42.

Weppe, Alexandre, Florian Moreau, and Didier Saury (Nov. 2021a). "Experimental study of a natural convection flow in a cubic enclosure with a partially heated inner block". In: *Journal of Physics: Conference Series* 2116.1, p. 012033.
Duffal, Vladimir, Benoît de Laage de Meux, and Remi Manceau (2022). "Development and Validation of a new formulation of Hybrid Temporal Large Eddy Simulation". In: *Flow, Turbulence and Combustion* 108, p. 42.

✓ 13 conferences:

Duffal, Vladimir, Benoît de Laage de Meux, and Remi Manceau (July 2019a). "Development and validation of a hybrid RANS/LES approach based on temporal filtering". In: *ASME - KSME Joint Fluids Engineering Conference 2019*. Proc. ASME - JSME - KSME Joint Fluids Engineering Conference 2019, Jul 2019, San Francisco, CA, United States. San Francisco, CA, United States.

Bikkanahally, Puneeth, Remi Manceau, and Franck Marippolito (Jan. 2021). "Development of a hybrid RANS-LES model based on temporal filtering for natural convection flows". In: *WCCM - 14th World Congress in Computational Mechanics, ECCOMAS Congress 2020*. Virtual, France.

Manceau, Remi (May 2018). "Modélisation des transferts thermiques turbulents (conférence plénière)". In: *26e congrès français de thermique*. Pau, France.

Jena, Sofen Kumar, Puneeth Bikkanahally, and Remi Manceau (Dec. 2022). "Numerical simulation of a turbulent natural convection flow in a cubic cavity with centrally placed partially heated inner obstacle". In: *3rd high-fidelity industrial LES/DNS symp. (HiFiLeD)*. Brussels, Belgium.

Manceau, Remi (Oct. 2019b). "Modelling of turbulent natural convection (keynote lecture)". In: *16th ERCOFTAC SIG15 Workshop on Modelling of wall bounded turbulent natural convection*. Jozef Stefan Institute (IJS). Ljubljana, Slovenia.

Bikkanahally, Puneeth and Remi Manceau (Oct. 2020). "Modeling turbulent flows in the natural convection regime using hybrid RANS-LES approaches". In: *jspyrene2020 : Journée Scientifique autour du cluster Pyrene et autres moyens de calcul 2020*. Pau, France.
Manceau, Remi and Puneeth Bikkanahally (Sept. 2021). "Hybrid Temporal LES: from theory to applications". In: *HiFiLeD - 2nd High Fidelity Industrial LES/DNS Symposium*. Toulouse / Virtual, France.

Duffal, Vladimir, Benoît de Laage de Meux, and Remi Manceau (Sept. 2021). "A new formulation of hybrid temporal large-eddy simulation". In: *ETMM 2021 - 13th International ERCOFTAC symposium on engineering, turbulence, modelling and measurements*. Rhodes / Virtua, Greece.

Jameel, Syed Mohd Saad, Remi Manceau, and Vincent Herbert (Sept. 2019a). "A buoyancy extension for eddy-viscosity models for the natural convection regime". In: *17th European Turbulence Conference (ETC-2019)*. Torino, Italy.

– (July 2019b). "Sensitization of eddy-viscosity models to buoyancy effects for predicting natural convection flows". In: *HEFAT 2019 - 14th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics*. Proc. HEFAT 2019 - 14th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics. Wicklow, Ireland.

Mangeon, Gaëtan, S. Benhamadouche, Jean-François Wald, and Remi Manceau (Sept. 2018a). "Modelling of the dissipation rate of the temperature variance". In: *ETMM12 - 12th International ERCOFTAC Symposium on Engineering Turbulence Modelling and Measurements*. Montpellier, France.

Mangeon, Gaëtan, Sofiane Benhamadouche, Jean-François Wald, and Remi Manceau (July 2018c). "Unifying the near-wall treatment of the turbulent heat fluxes for all kinds of temperature boundary conditions with the Elliptic Blending approach". In: *THMT-18 - 9th International Symposium on Turbulence, Heat and Mass Transfer*. Rio De Janeiro, Brazil.

Weppe, Alexandre, Florian Moreau, and Didier Saury (Sept. 2021b). "Experimental study of Natural convection flow in a cubic enclosure with a partially heated inner block". In: *EUROTHERM2020 - 8th European Thermal Sciences Conference*. Lisbonne, Portugal.
✓ 5 posters:

Mangeon, Gaëtan, Sofiane Benhamadouche, Remi Manceau, and Jean-François Wald (May 2019). *Conjugate heat transfer: A big challenge for RANS modeling*. Code_Saturne user meeting. Poster.

Jameel, Syed Mohd Saad, Remi Manceau, and Vincent Herbert (Dec. 2017). *Turbulence modelling of mixed and natural convection flow in underhood space of automobiles*. Journée doctorants PSA. Poster.

Mangeon, Gaëtan, Sofiane Benhamadouche, Remi Manceau, and Jean-François Wald (May 2018b). *Modeling of the dissipation rate of the temperature variance*. Code_Saturne user meeting. Poster.

Duffal, Vladimir, Remi Manceau, and Benoît de Laage de Meux (May 2019b). *Hybrid RANS/LES modelling of unsteady turbulent loads in hydraulic pumps. A hybrid approach based on temporal filtering*. Code_Saturne user meeting. Poster.

Duffal, Vladimir, Benoît de Laage de Meux, and Remi Manceau (May 2018). *Hybrid RANS/LES modelling of unsteady turbulent loads in hydraulic pumps*. Code_Saturne user meeting. Poster.
Acknowledgements

R. Manceau thanks:

✓ The Agence Nationale de la Recherche for partially financing the project MONACO_2025 (ANR-17-CE06-0005-01_ACT)

✓ The MCIA, Bordeaux, for providing computing resources

✓ GENCI-IDRIS for providing computing resources under the grants A0072A10980 and A0102A10980