Particle-to-fluid heat transfer in particle-laden turbulence

Preferential concentration of inertial particles by turbulence is a well recognized phenomenon. This study investigates how this phenomenon impacts the mean heat transfer between the fluid phase and the particle phase. Using direct numerical simulations of homogeneous and isotropic turbulent flows coupled with Lagrangian point particle tracking, we explore this phenomenon over wide range of input parameters. Among the nine independent dimensionless numbers defining this problem, we show that particle Stokes number, defined based on large eddy time, and a new identified number called heat mixing parameter have the most significant effect on particle to gas heat transfer, while variation in other non-dimensional numbers can be ignored. An investigation of regimes with significant particle mass loading, suggests that the mean heat transfer from particles to gas is hardly affected by momentum two-way coupling. Using our numerical results we propose an algebraic reduced order model for heat transfer in particle-laden turbulence.