NUMERICAL SIMULATION OF THERMAL PLUMES USING LATTICE BOLTZMANN METHOD

Mostafa Taha (1) , Aymeric Lamorlette (1) , J Consalvi (2) , Pierre Boivin (1)

1 M2P2 - Laboratoire de Mécanique, Modélisation et Procédés Propres
2 IUSTI - Institut universitaire des systèmes thermiques industriels

Thermal plumes are involved in many aspects of fire safety including wildfires, fire detection, and fire suppression. Consequently, the accurate prediction of those turbulent plumes is fundamental and indispensable. In the literature many works on thermal plumes were reported, from the early correlative approaches from experiments to more recent numerical simulations. Most of numerical studies have considered numerical simulations based on Navier-Stokes equations from direct numerical simulation, DNS, large eddy simulation, LES, reaching Reynolds Averaged Navier Stokes, RANS. In this work, a new promising technique is investigated, utilizing a whole different set of equations called the Lattice Boltzmann equations. The speed of the LBM makes it attractive nowadays compared to classical Navier-Stokes solvers. The need of such a low cost method rises from the huge computational resources required for LES in large–scale plumes. Hybrid LBM-NS will be used in this study where the LBM will be used for mass and momentum conservations while the usual Navier-Stokes formulation will be considered for the energy equation. This hybrid technique is chosen because it is easily extendable afterwards for fire plume simulations where combustion will be required. Free inlet/outlet boundary conditions are considered along the sides and at the top boundary of the computational domain, a no slip boundary condition is applied on the ground, as for the inlet a velocity profile is imposed in addition to a constant heat input or temperature. Different collision models and sub-grid models are assessed and different levels of refinements are exploited for mesh convergence study. Comparisons and validations with other numerical simulations are held to demonstrate the potential inherited in the LBM from both accuracy and cost points of view. Experimental results and analytical solutions from the literature will be used for validation as well.

Mots clés: CFD; Lattice Boltzmann method; ProLB; Thermal plumes; Buoyancy force; Turbulent flow

Domaines: Mécanique des fluides [physics.class-ph]

Mostafa Taha, Aymeric Lamorlette, J Consalvi, Pierre Boivin. NUMERICAL SIMULATION OF THERMAL PLUMES USING LATTICE BOLTZMANN METHOD. 14th World Congress in Computational Mechanics (WCCM) ECCOMAS Congress 2020, Jul 2020, Paris, France. ⟨hal-03598490⟩