Influence of Evaporating Droplets in the Turbulent Marine Atmospheric Boundary Layer

Peng, Tianze; Richter, David H.

doi:10.1007/s10546-017-0285-7

Cited by 18 publications

(24 citation statements)

References 32 publications

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“…The observed saturation of

{\overset{true¯}{Q}}_{S}^{d}

for drops with V s / κu * > 1 can be related to their shorter residence time in the air. The behavior of the drop‐mediated latent and sensible heat fluxes in Figure 8 is also consistent with the observation by Peng and Richter () that small droplets add as much latent heat flux as they take away from the sensible heat flux, whereas large droplets (with V s / κu * > 1 and relatively short residence times) do not reach the equilibrium temperature as quickly, and so can contribute to the enthalpy flux.…”

Section: Numerical Resultssupporting

confidence: 88%

“…This reduction does not affect the feedback momentum and heat fluxes but makes the residence times of drops considered in DNS (based on the ratio V s /κu * ) similar to the adopted estimates of residence times of spume drops in the air in natural conditions. Similar reduced-gravity conditions were considered by Peng and Richter (2017) in the DNS study of droplet-laden open channel flow modeling MABL.…”

Section: 1029/2018jc014346mentioning

confidence: 95%

“…In their later study, Richter and Sullivan () considered the feedback effects of solid, nonevaporating particles on the vertical turbulent heat flux and found it to be significant. Thermodynamic coupling between evaporating particles/droplets and air and its influence on the sensible and latent heat fluxes were further studied by Helgans and Richter () in a particle‐laden turbulent Couette flow in zero‐gravity environment and by Peng and Richter () in a droplet‐laden open channel flow with gravitational settling taken into account. The results of both studies show that evaporating droplets have opposite effects with regard to bulk sensible and latent heat transfer.…”

Section: Introductionmentioning

confidence: 99%

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The Study of Momentum, Mass, and Heat Transfer in a Droplet‐Laden Turbulent Airflow Over a Waved Water Surface by Direct Numerical Simulation

2018

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This paper investigates turbulent exchange processes in a droplet‐laden air flow over a waved water surface by performing direct numerical simulation (DNS). Turbulent Couette flow is considered in DNS as a model of a constant‐flux layer in the marine atmospheric surface layer. Two‐dimensional stationary waves at the water surface are prescribed and assumed to be unaffected by the airflow and/or droplets. Evaporating droplets of different sizes are injected into the air in the vicinity of wave crests with initial velocities and temperatures of water, and thus mimicking spume sea‐spray droplets. Evolution equations of the airflow velocity, temperature, and humidity are solved in a Eulerian framework simultaneously with the equations of individual droplets coordinates and velocities, temperatures, and masses tracked in a Lagrangian framework. The momentum (Qm) and sensible (QS) and latent (QL) heat fluxes from the droplets to air are evaluated both as phase‐averaged Eulerian fields and as fluxes integrated over time along Lagrangian droplets trajectories. The results show that droplets extract momentum from the surrounding air (Qm < 0), and QL > 0 and increases with droplet diameter, d, whereas QS < 0, reaches maximum for droplets with diameters of the order of 200 μm, and saturates for larger droplets. The resulting enthalpy flux QS + QL > 0 vanishes for droplets with diameters d < 100 μm, and increases with d for larger droplets. DNS results also show that droplets reduce mean air velocity and temperature and increase relative humidity as compared to the droplet‐free flow.

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“…The observed saturation of

{\overset{true¯}{Q}}_{S}^{d}

Section: Numerical Resultssupporting

confidence: 88%

Section: 1029/2018jc014346mentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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The Study of Momentum, Mass, and Heat Transfer in a Droplet‐Laden Turbulent Airflow Over a Waved Water Surface by Direct Numerical Simulation

2018

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“…In the former, scalars are treated as a continuous field on the computational grid (Chamecki et al, ), while in the latter, aerosols are treated as Lagrangian point particles that are advected and dispersed by the local velocity interpolated from the LES computational mesh. Other numerical methodologies, including direct numerical simulation (DNS) and Lagrangian stochastic models, have been utilized for studying spray aerosol processes in the MABL as well (Mueller & Veron, , ; Peng & Richter, ; Richter & Chamecki, ). The goal of these techniques is to accurately resolve turbulence in ways unattainable on coarse global‐ or regional‐scale model grids, then to use this information to better parameterize unresolved turbulent transport processes in the MABL.…”

Section: Introductionmentioning

confidence: 99%

Parameterized Vertical Concentration Profiles for Aerosols in the Marine Atmospheric Boundary Layer

et al. 2018

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Information about sea spray aerosol particle transport and their vertical distribution in the marine atmospheric boundary layer (MABL) is important in marine meteorological forecasting and geobiochemical models. However, due to difficulties in field observations, values of aerosol concentration are often limited to point measurements, and obtaining the size‐resolved concentration profiles is quite challenging. Hence, numerical and analytical studies are vital in modeling the transport of aerosols in the atmospheric boundary layer and beyond. Due to their coarse resolution, most mesoscale and global aerosol models do not accurately resolve the sea spray and aerosol concentrations in the MABL, especially in the surface layer. The objective of the present study is to develop a relatively simple, one‐dimensional analytical model to calculate concentration profiles of aerosols in the MABL. In this study, a new analytical model relating surface flux to vertical concentration profile in the MABL is proposed. The model accounts for the different atmospheric stability and particle settling velocity, thus providing size‐resolved vertical profiles of aerosol concentration. The equations developed here extend the surface layer similarity models to the mixed layer. Model results are compared to aerosol concentration profiles emitted from a surface source obtained from large eddy simulations, for both neutral and unstable atmospheric stability and for particle sizes ranging from 1 to 30 μm. Though the model is developed for sea spray aerosols, it can be used to calculate vertical concentration profiles for other types of settling particles, including dust and sand particles in the atmospheric boundary layer.

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“…In particular, a primary objective is to assess the accuracy of equilibrium theories such as that of Prandtl (1952) which are frequently used in inferring sea surface generation functions for spray and marine aerosols. To achieve this goal, we combine the LES model of Sullivan et al (2018b) with a Lagrangian treatment of spray droplets as implemented, for example, in Richter and Sullivan (2013) and Peng and Richter (2017). The use of Lagrangian droplets coupled to an Eulerian flow field is an increasingly popular method for studying particle-turbulence interaction (Balachandar and Eaton 2010), and has been used in the past for investigating wavy surfaces as well (Marchioli et al 2006;Druzhinin et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Turbulent Transport of Spray Droplets in the Vicinity of Moving Surface Waves

Richter

Dempsey

Sullivan

2019

Journal of Physical Oceanography

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A common technique for estimating the sea surface generation functions of spray and aerosols is the so-called flux–profile method, where fixed-height concentration measurements are used to infer fluxes at the surface by assuming a form of the concentration profile. At its simplest, this method assumes a balance between spray emission and deposition, and under these conditions the concentration profile follows a power-law shape. It is the purpose of this work to evaluate the influence of waves on this power-law theory, as well as investigate its applicability over a range of droplet sizes. Large-eddy simulations combined with Lagrangian droplet tracking are used to resolve the turbulent transport of spray droplets over moving, monochromatic waves at the lower surface. The wave age and the droplet diameter are varied, and it is found that droplets are highly influenced both by their inertia (i.e., their inability to travel exactly with fluid streamlines) and the wave-induced turbulence. Deviations of the vertical concentration profiles from the power-law theory are found at all wave ages and for large droplets. The dynamics of droplets within the wave boundary layer alter their net vertical fluxes, and as a result, estimates of surface emission based on the flux–profile method can yield significant errors. In practice, the resulting implication is that the flux–profile method may unsuitable for large droplets, and the combined effect of inertia and wave-induced turbulence is responsible for the continued spread in their surface source estimates.

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Influence of Evaporating Droplets in the Turbulent Marine Atmospheric Boundary Layer

Cited by 18 publications

References 32 publications

The Study of Momentum, Mass, and Heat Transfer in a Droplet‐Laden Turbulent Airflow Over a Waved Water Surface by Direct Numerical Simulation

The Study of Momentum, Mass, and Heat Transfer in a Droplet‐Laden Turbulent Airflow Over a Waved Water Surface by Direct Numerical Simulation

Parameterized Vertical Concentration Profiles for Aerosols in the Marine Atmospheric Boundary Layer

Turbulent Transport of Spray Droplets in the Vicinity of Moving Surface Waves

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