Katul , G , Mammarella , I , Grönholm , T & Vesala , T 2018 , ' A Structure Function Model Recovers the Many Formulations for Air-Water Gas Transfer Velocity ' , Water Resources Research , vol. 54 , no. 9 , pp. 5905-5920 . https://doi.org/10.1029/2018WR022731
Title: | A Structure Function Model Recovers the Many Formulations for Air-Water Gas Transfer Velocity |
Author: | Katul, Gabriel; Mammarella, Ivan; Grönholm, Tiia; Vesala, Timo |
Contributor organization: | Department of Physics |
Date: | 2018-09 |
Language: | eng |
Number of pages: | 16 |
Belongs to series: | Water Resources Research |
ISSN: | 0043-1397 |
DOI: | https://doi.org/10.1029/2018WR022731 |
URI: | http://hdl.handle.net/10138/298625 |
Abstract: | Two ideas regarding the structure of turbulence near a clear air-water interface are used to derive a waterside gas transfer velocity k(L) for sparingly and slightly soluble gases. The first is that k(L) is proportional to the turnover velocity described by the vertical velocity structure function D-ww(r), where r is separation distance between two points. The second is that the scalar exchange between the air-water interface and the waterside turbulence can be suitably described by a length scale proportional to the Batchelor scale l(B) = Sc-1/2, where Sc is the molecular Schmidt number and eta is the Kolmogorov microscale defining the smallest scale of turbulent eddies impacted by fluid viscosity. Using an approximate solution to the von Karman-Howarth equation predicting D-ww(r) in the inertial and viscous regimes, prior formulations for k(L) are recovered including (i) kL = root 2/15Sc(-1/2)v(K), v(K) is the Kolmogorov velocity defined by the Reynolds number v(K)eta/nu = 1 and nu is the kinematic viscosity of water; (ii) surface divergence formulations; (iii) k(L) alpha Sc(-1/2)u(*), where u(*) is the waterside friction velocity; (iv) k(L) alpha Sc-1/2 root g nu/u(*) for Keulegan numbers exceeding a threshold needed for long-wave generation, where the proportionality constant varies with wave age, g is the gravitational acceleration; and (v) k(L) = root 2/15Sc(-1/2) (nu g beta(o)q(o))(1/4) in free convection, where q(o) is the surface heat flux and beta(o) is the thermal expansion of water. The work demonstrates that the aforementioned k(L) formulations can be recovered from a single structure function model derived for locally homogeneous and isotropic turbulence. |
Subject: |
air-water gas exchange
gas transfer velocity structure function microeddy model scaling laws turbulence NEAR-SURFACE TURBULENCE MASS-TRANSFER CARBON-DIOXIDE EDDY COVARIANCE SEA INTERFACE WIND-WAVES EXCHANGE EVAPORATION LIQUID FLOWS 114 Physical sciences |
Peer reviewed: | Yes |
Rights: | unspecified |
Usage restriction: | openAccess |
Self-archived version: | publishedVersion |
Total number of downloads: Loading...
Files | Size | Format | View |
---|---|---|---|
Katul_et_al_2018_Water_Resources_Research.pdf | 1.151Mb |
View/ |