Postdoc M/F : High-Performance Computing for multi-physics simulations of solar receivers with fluidized beds

Job Description

Missions

In solar receivers, solar radiation is concentrated on vertical tubes containing a gas-particle mixture, with the goal of heating particles to ~1000°C. However, current Euler-Euler (Two-Fluid Model, TFM) simulations fail to accurately predict wall-to-bed heat transfer coefficients, with discrepancies of up to a factor of 2 compared to experiments (e.g., 1200 W/(m²·K) vs. 600 W/(m²·K)). The complex physics involves:
• Multi-scale couplings (micrometric particles vs. meter-scale receivers).
• Radiative heat transfer between particles and walls.
• Collective particle phenomena (e.g., "packets" of particles).
• Complex particle shapes (flattened, sharp-edged) affecting hydrodynamics and heat transfer.
This postdoc will address these challenges by developing advanced simulations to bridge the gap between experiments and simulations. The multi-physics waLBerla framework is already capable of simulating particulate flows on large CPU clusters. In the project the challenge will be to extend and adapt the DEM simulation and the fluid coupling to particles of complex shape and taking into account of radiative heat transfers.

Activity

The postdoctoral researcher will contribute to the following key tasks:
1. High-Fidelity Simulations of Solar Receivers
• Develop fully resolved simulations using the waLBerla framework (DEM for particles + LBM for fluid).
• Model radiative heat transfer between particles and walls, as well as particle-particle radiation.
• Account for complex particle shapes (non-spherical geometries) and their impact on near-wall concentration and heat transfer.

2. Multi-Physics Coupling
• Investigate couplings between temperature, velocity, and two-phase flow in asymmetrically heated receivers.
• Study local phenomena (e.g., individual particle heating, gas property variations) and their impact on global receiver performance.
• Validate simulations against experimental data.

3. Scalability and Performance Optimization
• Perform large-scale simulations (>10⁶ particles) to capture collective phenomena (e.g., coordinated particle motion near walls).
• Optimize computational performance for exascale computing (CPU/GPU acceleration).
• Collaborate with FAU (Friedrich-Alexander-Universität Erlangen-Nürnberg) and other European partners.

Your Profil

Skills

PhD in Fluid Mechanics, Computational Engineering, Thermal Sciences, or a related field.
Strong background in:
o Numerical methods (DEM, LBM, CFD).
o Multiphase flow modeling (gas-solid flows, fluidized beds).
o Heat transfer (conduction, convection, radiation).
Experience in:
o High-performance computing (HPC) (MPI, OpenMP, GPU acceleration).
o Scientific programming (C++, Python, Fortran).
o Open-source or commercial CFD codes (waLBerla, OpenFOAM, Neptune_CFD, TrioCFD…).
o Particle-resolved simulations.

Your Work Environment

The PROMES-CNRS Laboratory (Processes, Materials, and Solar Energy) invites applications for a postdoctoral position focused on high-fidelity modeling of wall-to-bed heat transfers in high-temperature solar receivers. This research is part of projects which aim to develop innovative concentrated solar power (CSP) technologies using gas-solid circulating dense fluidized beds as an alternative to traditional heat transfer fluids. The proposed work is part of the European project LBM4HPC: Lattice Boltzmann for Exascale. The project introduces a unifying abstraction layer specifically designed for the algorithmic structure and performance requirements of LBM-based solvers that decouples problem formulation from solver implementation and hardware-specific optimization.

Constraints and risks

Computer work

Compensation and benefits

Compensation

from 3071€ gross per month, depending on experience.

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

The research professions