Mean Heat Flux Modulation by Particle Thermal Feedback in a Thermally Inhomogeneous Flow

We investigate how particle thermal feedback modulates heat flux in a turbulent shearless flow. This is done by utilizing a recently developed decomposition of the velocity-temperature correlation into particle velocity and temperature time derivative correlations. A set of Eulerian-Lagrangian point-particle direct numerical simulations (DNSs) with a Taylor microscale Reynolds number from 56 to 124 have been carried out. These simulations cover a broad spectrum of thermal Stokes numbers and Stokes numbers at a constant volume fraction, providing insight into the role of thermal feedback. Our findings indicate that thermal feedback has a more significant impact on particle heat flux compared to fluid convective heat flux, with both exhibiting opposite effects in a two-way coupling regime. Additionally, we explore the reasons behind the observed behavior of the global particle contribution to the heat flux ratio and identify the main factors that can either diminish or amplify this ratio under varying conditions of particle inertia and thermal inertia.