Study of Evaporation from Wavy Surfaces by Coupled Turbulent Air Flow and Porous Media Flow
Abstract
The introduction of a topographical-level soil surface (large-scale roughness or wavy surfaces) is of great significance in agricultural hydrology (e.g. tilled soil), canopy flows, and submarine sediment transport, etc. Surface topology can have a significant influence on mass/energy interactions between the subsurface and the atmosphere during evaporation. The naturally occurring turbulent air flow above a wavy surface may enhance the influences. However, most previous works only consider evaporation behavior from flat surfaces, or do not incorporate both porous media flow and atmospheric flow for studying turbulence over wavy soil surfaces. The goal of this work is to provide an initial understanding of evaporation from irregular soil surfaces at the REV scale by experimental and numerical approaches. A coupled free flow and porous media flow model was developed to describe evaporation under non-isothermal conditions. Turbulent air flow was taken into consideration. Experiments using an open-ended wind tunnel and soil tank were conducted and two wavy surfaces were built. The experimental system was instrumented with various environmental sensors to continuously collect atmospheric and subsurface data. Both particle imaging velocimetry (PIV) and hotwire were applied to capture the velocity profile above the soil surface. Experimental results show that the evaporation first happened at the uphill area of the upward wavy surface. Initial modeling results considering turbulence show that the existence of a recirculation area leads to a local thicker boundary layer and a local minimum value of the diffusive flux. Future work will focus on the influence of wavy surfaces and turbulence on evaporation by experimental and numerical modeling approaches.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A31K3012G
- Keywords:
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- 0315 Biosphere/atmosphere interactions;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3307 Boundary layer processes;
- ATMOSPHERIC PROCESSESDE: 3322 Land/atmosphere interactions;
- ATMOSPHERIC PROCESSESDE: 3379 Turbulence;
- ATMOSPHERIC PROCESSES