TY - JOUR
T1 - Role of Bioroughness, Bioirrigation, and Turbulence on Oxygen Dynamics at the Sediment-Water Interface
AU - Liu, Y.
AU - Reible, D.
AU - Hussain, F.
AU - Fang, H.
N1 - Funding Information:
This research is supported by the Donovan Maddox Distinguished Engineering Chair and also by the President's Endowed Distinguished Chair in Engineering, Science, & Medicine ‐ both at Texas Tech University. The computations are supported by Texas Tech University's High Performance Computing Center (HPCC) using the in‐house model code, Hydro3D. The simulation input files and model code are available at this site ( https://www.depts.ttu.edu/ceweb/groups/reiblesgroup/downloads.html ).
Publisher Copyright:
©2019. American Geophysical Union. All Rights Reserved.
PY - 2019/10/1
Y1 - 2019/10/1
N2 - Models that have been developed to quantify the oxygen flux at the sediment-water interface (SWI) generally do not explicitly consider the influence of bioroughness (mounds and burrows) and bioirrigation. We performed a numerical study of the influence of overlying water velocity, bioroughness, and bioirrigation on the oxygen flux across the SWI. We found that compared with a flat bed, bioroughness significantly increases O2 transport at the SWI as a result of enhanced turbulence and pressure differences across the roughness. Bioirrigation can also enhance O2 transport across the SWI by a factor of up to 10 when the roughness Reynolds number (Re*) is low, but the influence of bioirrigation decreases with increasing Re*. Burrows increase O2 penetration depth, and bioirrigation causes asymmetric distributions of O2 along burrows. Despite the complexity of O2 distribution in sediments, the net exchange across the SWI can be described by the relationship of O'Connor and Harvey (2008, https://doi.org/10.1029/2008WR007160) (Formula presented.) when the shape is two-dimensional or when the burrow density is low. When the burrow density is large, flow is three-dimensional and flow interactions between burrows become important. Under these conditions the net exchange across the SWI increases by up to a factor of 4. A burrow number is introduced, Bu = [burrow density]1/2 [burrow height], to correct the coefficient in O'Connor and Harvey's relationship, that is, a = 0.005 for Bu < 0.05 and a = 0.02 for Bu ≫ 0.1.
AB - Models that have been developed to quantify the oxygen flux at the sediment-water interface (SWI) generally do not explicitly consider the influence of bioroughness (mounds and burrows) and bioirrigation. We performed a numerical study of the influence of overlying water velocity, bioroughness, and bioirrigation on the oxygen flux across the SWI. We found that compared with a flat bed, bioroughness significantly increases O2 transport at the SWI as a result of enhanced turbulence and pressure differences across the roughness. Bioirrigation can also enhance O2 transport across the SWI by a factor of up to 10 when the roughness Reynolds number (Re*) is low, but the influence of bioirrigation decreases with increasing Re*. Burrows increase O2 penetration depth, and bioirrigation causes asymmetric distributions of O2 along burrows. Despite the complexity of O2 distribution in sediments, the net exchange across the SWI can be described by the relationship of O'Connor and Harvey (2008, https://doi.org/10.1029/2008WR007160) (Formula presented.) when the shape is two-dimensional or when the burrow density is low. When the burrow density is large, flow is three-dimensional and flow interactions between burrows become important. Under these conditions the net exchange across the SWI increases by up to a factor of 4. A burrow number is introduced, Bu = [burrow density]1/2 [burrow height], to correct the coefficient in O'Connor and Harvey's relationship, that is, a = 0.005 for Bu < 0.05 and a = 0.02 for Bu ≫ 0.1.
KW - LES
KW - bioturbation
KW - burrow
KW - hyporheic exchange
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U2 - 10.1029/2019WR025098
DO - 10.1029/2019WR025098
M3 - Article
AN - SCOPUS:85074367597
SN - 0043-1397
VL - 55
SP - 8061
EP - 8075
JO - Water Resources Research
JF - Water Resources Research
IS - 10
ER -