Lattice-Boltzmann simulation of heat transfer in turbulent pipe flows seeded with resolvednon-spherical particles

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Turbulent flows laden with particles are ubiquitous in a wide range of industrial and natural processes including biomass combustion, pollutant transport, sand storms, icy clouds, etc. In most of these applications particle shape is not spherical. Numerical simulation of turbulent flows with non-spherical particles is complicated because the orientation and distribution of particles play an important role and can significantly modify flow and turbulence behavior. Most numerical studies dealing with turbulent flows involving non-spherical particles are limited to point particles. However, when particles become larger than the Kolmogorov length scale, simulations become more complex and demand large computational efforts. Very few numerical studies of turbulent flows with interface-resolved non-spherical particles can be found in the scientific literature up to now. Most of these studies have considered isothermal conditions. However, heat transfer from/to particles can again significantly alter all flow properties. Hot particles can also modify the turbulence spectra through pressure dilatation. Such effects have never been addressed thoroughly in the past. The goal of this study is to bridge this gap by performing direct numerical simulation (DNS) of turbulent flows containing non-spherical particles and considering heat transfer effects. Given the complexity of the problem and very high computational costs required for the simulations, a lattice Boltzmann method (LBM) solver is chosen for this study. Due to the locality of all operations, parallel computations are straightforward with LBM. Moreover, it can relatively easily be applied to complex domains, which makes it suitable for the purpose of the present proposal. To this end, an immersed boundary method (IBM) combined with an LBM solver will be employed. In order to deliver information relevant for practical applications, the final simulations will consider a pipe flow, opening the door for a better physical understanding of important phenomena like particle position in catalytic reactors, or fouling in heat exchangers. Such DNS (here based on LBM) will improve our understanding of the physical transfer mechanisms. Combining turbulence, non-isothermal and fluid dynamics aspects and considering the mutual interactions that occur during the motion of non-spherical particles are the central goals of this proposal. The results of this study will also enable practical progress concerning heat transfer enhancement, possibly coupled to drag-reduction effects.