DOI: 10.1615/ICHMT.2009.CONV
ISBN Print: 978-1-56700-261-4
ISSN Online: 2642-3499
ISSN Flash Drive: 2642-3502
LES-BASED PREDICTION OF DEPOSIT FORMATION ON A WALL-BOUNDED SHORT CYLINDER
ABSTRACT
We present some results of unsteady Lagrangian numerical simulations of the dynamics of wall deposition of particles in a turbulent flow over a single short cylinder (h/d=0.4) bounded by heated end-walls, as found in common plate-fin-and-tube heat exchangers. The particles are assumed to be non-reacting, relatively large (d >1 μm) and passive, with no feedback on the fluid velocity or heat transfer. The simulations were performed using the instantaneous velocity and temperature fields generated from an a priori LES (Borello et al., [2008]). The particle dispersion due to turbulence is described by the Particle Cloud Tracking (PCT) of Baxter (1989) and the deposition criteria are based on the minimum shear velocity evaluated from the hydrodynamic rolling moment due the drag force against the adhesion moment on the surface. Some results are presented for two cases, the first corresponding to a long integration time by considering a large number of dense clouds, and the second with the integration over a single vortex shedding period considering a selection of small dilute clouds. The latter case reflects well the unsteady velocity field, showing irregularly scattered deposition sites on the cylinder and the bounding top and bottom walls corresponding to the imprints of dominant vortical structures.