Condensation-induced flow structure modifications in turbulent channel flow investigated in direct numerical simulations

TL;DR

This study uses direct numerical simulations to explore how condensation-induced heat release affects turbulence and flow structures in a cooled vertical channel, revealing increased streak spacing and turbulence modulation.

Contribution

It introduces a coupled model of condensation and turbulence in channel flow, highlighting the impact of latent heat release on flow structures and turbulence damping.

Findings

Latent heat release increases post-interaction streak spacing.

Condensation opposes wall cooling, affecting turbulence damping.

Flow modifications are observed due to localized phase transition events.

Abstract

The turbulent flow of a fluid carrying trace amounts of a condensable species through a differentially cooled vertical channel geometry is simulated using single-phase direct numerical simulations. The release of latent heat during condensation is modeled by interdependent temperature and vapor concentration source terms governing the relation between the removal of excess vapor from the system and the associated local increase in fluid temperature. A coupling between condensation and turbulence is implemented via solutal and thermal buoyancy. When compared to simulations of an identical system without phase transition modeling, the modifications of the subcooled boundary layer due to the transient and highly localized release of latent heat could be observed. A separate analysis of fluid before and after phase transition events shows a clear increase in post-interaction streak spacing, with the release of latent heat during condensation events opposing the cooling effect of the channel wall and the associated damping of turbulence.