Direct Numerical Simulation of the Moist Stably Stratified Surface Layer: Turbulence and Fog Formation

Show simple item record MacDonald, Michael en Kurowski, MJ en Teixeira, J en 2020-06-02T22:27:36Z en 2020-03-27 en
dc.identifier.issn 0006-8314 en
dc.identifier.uri en
dc.description.abstract We investigate the effects of condensation and liquid water loading on the stably stratified surface layer, with an eye towards understanding the influence of turbulent mixing on fog formation. Direct numerical simulations of dry and moist open-channel flows are conducted, where in both a constant cooling rate is applied at the ground to mimic longwave radiative cooling. Depending on the cooling rate, this can lead to either turbulent (weakly stable) or laminar (very stable) flows. Compared to the completely dry case, the condensation of liquid water in the moist case enables slightly higher cooling rates to be achieved before leading to turbulence collapse. In the very stable cases, runaway cooling leads to the substantial condensation of liquid water close to the ground and fog (visibility less than 1 km) results over much of the domain. In the weakly stable cases, turbulent mixing narrowly yields visibilities of 1 km close to the ground over a similar time period. However, despite the idealized nature of the system, the present results suggest that turbulence impedes, although will not necessarily inhibit, fog formation. A possible mechanism for fog formation within turbulent flows is identified, wherein regions of increased liquid water content form within the low-speed streaks of the near-wall cycle. These streaks are energized in the moist cases due to reduced dissipation of turbulence kinetic energy compared to the dry case, although in both cases the streaks are less energetic and persistent than in neutrally-stratified flow. en
dc.publisher Springer (part of Springer Nature) en
dc.relation.ispartofseries Boundary-Layer Meteorology en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri en
dc.title Direct Numerical Simulation of the Moist Stably Stratified Surface Layer: Turbulence and Fog Formation en
dc.type Journal Article en
dc.identifier.doi 10.1007/s10546-020-00511-2 en
pubs.begin-page 343 en
pubs.volume 175 en
dc.rights.holder Copyright: The author en
pubs.end-page 368 en
dc.rights.accessrights en
pubs.subtype Article en
pubs.elements-id 797544 en Engineering en Mechanical Engineering en
pubs.record-created-at-source-date 2020-04-08 en

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