STUDY ON CONTAMINANT TRANSPORT AT THE SEDIMENT-WATER INTERFACE IN OSCILLATING FLOW
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摘要: 潜流带中污染物质交换与输运特性是影响水资源环境的重要问题之一. 本文对底部为高渗透沉积层的三维槽道振荡流高Schmidt数传质问题进行了大涡模拟研究. 采用动力学亚格子模型来封闭滤波后的三维不可压缩Navier-Stokes方程以及污染物输运方程, 同时采用修正的Darcy-Brinkman-Forcheimer模型来描述沉淀有锌离子污染溶质的可渗透沉积层. 通过对沉积层内外流场和浓度场的统计特性以及瞬态结构的分析, 探究了上覆水体中振荡流驱动作用对污染物输运的动力学影响以及扩散率随振荡周期和振荡角的变化规律. 研究结果表明, 浓度通量中的湍流浓度分量在垂向物质交换中起主导作用, 流向、展向速度, 湍流强度和污染物浓度的波动跟随振荡驱动力呈现准周期变化, 同时发现沉积层−水交界面处的湍流浓度通量与法向湍流强度两者之间的变化具有明确的相关性. 并且在较大振荡角和低频振荡的情况下, 沉积层−水交界面处的有效扩散率增大, 这主要是来自于沉积层−水交界面处流体的猝发行为有效促进了湍流混合和物质交换, 进而增强了污染物的垂向输运.Abstract: The exchange and transport characteristics of pollutants in the hyporheic zone are one of the important issues affecting the water resources environment. In this paper, the high Schmidt number mass transfer phenomenon of a channel oscillatory flow with a highly permeable sediment layer at the bottom is numerically investigated by using large eddy simulations. A modified Darcy-Brinkman-Forcheimer model describes the bottom highly permeable sediment layer using the volume-averaged Navier-Stokes equation and convective diffusion equation for the flow and transport of metal ion contaminants within the sediment layer. We explore the statistical characteristics and the instantaneous structure of flow field and concentration field, and the dynamic influence of oscillating flow inside and outside the sediment-water interface on the transport of pollutants. In addition, the variation of the effective diffusivity at the sediment-water interface with oscillation period and oscillation angle is also studied. The results show that the turbulence component of concentration flux plays a dominant role in vertical mass transport, and the streamwise and spanwise velocity, the fluctuations of turbulence intensity and pollutant concentration follow the quasi-periodic variation of periodic oscillation driving force. At the same time, it is found that there is a clear correlation between the variation of turbulent concentration flux at the sediment-water interface and the intensity of normal turbulence, and the effective diffusivity at the sediment-water interface increases at larger oscillation angles and low-frequency oscillations, which mainly comes from the burst behavior of the fluid at the sediment-water interface that significantly promotes turbulent mixing and material exchange, and then the concentration scalar is acted on by a convection-diffusion mechanism, which in turn enhances the vertical mass transport of pollutants.
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Key words:
- oscillatory flow /
- permeable sediment /
- hyporheic exchange /
- zinc ions /
- large eddy simulation
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图 1 底部含有沉积层上部为自由面的槽道振荡流动模型示意图
Figure 1. The sketch of the oscillatory flow model of a channel with a sediment layer at the bottom and a free surface at the top
图 3 平均浓度在垂向的分布
Figure 3. Profiles of the mean concentration along the vertical direction
图 4 振荡驱动力
${P_g}$ 与体积平均的展向速度${W_b}$ 、流向速度${U_b}$ 、湍动能${E_k}$ 的关系(a)$ A = {15^ \circ },T = 3 $ (b)$ A = {15^ \circ },T = 12 $ (c)$ A = {45^ \circ },T = 12 $ (d)$ A = {75^ \circ },T = 12 $ Figure 4. Oscillation driving force versus volume-averaged spanwise velocity
${W_b}$ , streamwise velocity${U_b}$ , turbulent kinetic energy${E_k}$ 
图 5 体积平均的流向速度、湍动能和沉积层内浓度随时间变化曲线. (a)
$ A = {15^ \circ },T = 3 $ (b)$ A = {15^ \circ },T = 12 $ (c)$ A = {45^ \circ },T = 12 $ (d)$ A = {75^ \circ },T = $ 12Figure 5. Volume-averaged streamwise velocity, turbulent kinetic energy, and concentration in sediment versus time
图 6 相位平均的法向湍流强度(a)
$ A = {15^ \circ },T = 3 $ (b)$ A = {15^ \circ }, $ $ T = 12 $ (c)$ A = {45^ \circ },T = 12 $ (d)$ A = {75^ \circ },T = 12 $ Figure 6. Profiles of phase-averaged wall-normal turbulent intensities
图 7
$A = {45^ \circ },T = 12$ 算例在x-z平面${y^ + } = 103$ 处法向速度脉动的等值线图($v' = \pm 2.0$ ). (a) t/T=4/8, (b) t/T=5/8, (c) t/T=6/8, (d) t/T=7/8, (e)相位点图Figure 7. Contour plot of the instantaneous wall-normal velocities (
$v' = \pm 2.0$ )parallel to the x-z plane(${y^ + } = 103$ ) for the$A = {45^ \circ },T = 12$ case
图 8 算例
$A = {45^ \circ },T = 12$ 在不同相位的法向浓度通量瞬时等值面分布图(z方向视图). 蓝色和棕色分别代表法向浓度通量值为$C'v' = 0.01$ 和$C'v' = - 0.01$ . (a) t/T=4/8, (b) t/T=5/8, (c) t/T=6/8, (d) t/T=7/8Figure 8. Contour maps of the instantaneous wall- normal convective concentration flux in different phases for
$A = {45^ \circ },T = 12$ (z-direction view). The blue and the brown iso-surface means$C'v' = 0.01$ and$C'v' = - 0.01$ .
图 9 流向平均速度(a)和平均浓度(b)沿法向分布 (细虚线为SWI位置)
Figure 9. Mean streamwise velocity and mean concentration distribution along the normal direction
图 10 雷诺应力在第二、四象限的分布(细虚线为SWI位置) (a) 第二象限 (b) 第四象限
Figure 10. Distribution of Reynolds stress in the second and fourth quadrants
图 11 浓度通量(a)和法向湍流强度(b)沿法向分布
Figure 11. Distribution of concentration flux (a) and turbulent intensities (b) along normal direction
图 12 不同振荡角和振荡周期与有效扩散系数的关系
Figure 12. Relationship between different oscillation angles and oscillation periods and effective diffusivity
表 1 流场物理参数(h = 10 cm)
Table 1. Physical parameters of flow field
$ \nu (c{m}^{2}{s}^{-1}) $ $ {D}_{w}(c{m}^{2}{s}^{-1}) $ $ {u}_{\tau }(cm{s}^{-1}) $ $ {C}_{\infty }(mg{l}^{-1}) $ $Sc$ $8.96 \times {10^{ - 3}}$ $2.40 \times {10^{ - 5}}$ $0.16$ $8.25$ $ 373 $ 
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表 2 不同算例的计算参数和湍流通量等统计量
Table 2. Calculation parameters and statistics such as turbulent flux for different cases
A T $ < {C_w} > $ $ < C'v'{ > _{SWI}}( \times {10^{ - 3}})$ $ < J{ > _{SWI}}( \times {10^{ - 6}})$ $ {15^ \circ } $ 3 0.177 1.63 2.39 $ {45^ \circ } $ 3 0.178 1.64 2.01 $ {75^ \circ } $ 3 0.178 1.63 1.81 $ {15^ \circ } $ 6 0.183 2.26 2.60 $ {45^ \circ } $ 6 0.183 2.00 1.98 $ {75^ \circ } $ 6 0.181 1.83 1.27 $ {15^ \circ } $ 12 0.208 2.59 1.50 $ {45^ \circ } $ 12 0.196 2.27 1.11 $ {75^ \circ } $ 12 0.204 2.12 0.57
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[1] Islam MS, Hossain MB, Matin A, et al. Assessment of heavy metal pollution, distribution and source apportionment in the sediment from Feni River estuary, Bangladesh. Chemosphere:Environmental toxicology and risk assessment, 2018, 202: 25-32 [2] Huang XF, Hu JW, Li CX, et al. Heavy-metal pollution and potential ecological risk assessment of sediments from Baihua Lake, Guizhou, P. R. China. International Journal of Environmental Health Research, 2009, 19(6): 405-419 doi: 10.1080/09603120902795598 [3] Jia YY, Wang L, Qu ZP, et al. Distribution, contamination and accumulation of heavy metals in water, sediments, and freshwater shellfish from Liuyang River, Southern China. Environmental Science and Pollution Research, 2018, 25: 7012-7020 doi: 10.1007/s11356-017-1068-x [4] Zhao GM, Ye SY, Yuan HM, et al. Surface sediment properties and heavy metal contamination assessment in river sediments of the Pearl River Delta, China. Marine Pollution Bulletin, 2018, 136: 300-308 doi: 10.1016/j.marpolbul.2018.09.035 [5] 赵剑琦. 湖震现象理论分析. 大学物理, 1998, (11): 12-13 (Zhao Jianqi. A theoretial analysics on phenomenon of science. College Physics, 1998, (11): 12-13 (in Chinese)) doi: 10.3969/j.issn.1003-5427.2013.04.001Liang Peiyu, Wang Xuan, Ma Fangbing. Effect of hydrodynamic conditions on water eutrophication: A review. Journal of Lake Science, 2013, 25: 455-462 (in Chinese) doi: 10.3969/j.issn.1003-5427.2013.04.001 [6] 赵剑琦. 湖震现象理论分析.大学物理, 1998, (11): 12-13Zhao Jianqi. A theoretial analysics on phenomenon of science. College Physics, 1998, (11): 12-13 (in Chinese) [7] Gundersen JK, Jorgensen BB. Microstructure of diffusive boundary layers and the oxygen uptake of the sea floor. Nature, 1990, 345: 604-607 doi: 10.1038/345604a0 [8] Higashino M, Stefan HG. Diffusive boundary layer development above a sediment-water interface. Water Environment Research, 2004, 76: 292-300 doi: 10.2175/106143004X141870 [9] Jabbari A, Boegman L. Parameterization of oscillating boundary layers in lakes and coastal oceans. Ocean Modelling, 2021, 160: 101-780 [10] Spalart PR, Baldwin BS. Direct Simulation of a Turbulent Oscillating Boundary Layer//Turbulent Shear Flows 6. Springer: Berlin Heidelberg, 1989. 417-440 [11] Reidenbach MA, Koseff JR, Monismith SG, et al. The effects of waves and morphology on mass transfer within branched reef corals. Limnology and Oceanography, 2006, 51: 1134-1141 doi: 10.4319/lo.2006.51.2.1134 [12] Lorke A, Müller B, Maerki M, et al. Breathing sediments: The control of diffusive transport across the sediment-water interface by periodic boundary-layer turbulence. Limnology and Oceanography, 2003, 48: 2077-2085 doi: 10.4319/lo.2003.48.6.2077 [13] Higashino M, Stefan HG, Gantzer CJ. Periodic diffusional mass transfer near sediment/water interface: Theory. Journal of Environmental Engineering, 2003, 129: 447-455 doi: 10.1061/(ASCE)0733-9372(2003)129:5(447) [14] Tian HJ, Li QX, Dong YH. Dissolved oxygen transfer from oscillatory flows to microbes in a permeable organic sediment bed. International Journal of Heat and Mass Transfer, 2020, 157: 119721 doi: 10.1016/j.ijheatmasstransfer.2020.119721 [15] Wang KP, Li QX, Dong YH. Transport of dissolved oxygen at the sediment-water interface in the spanwise oscillating flow. Applied Mathematics and Mechanics (English Edition) , 2021, 42: 527-540 doi: 10.1007/s10483-021-2719-6 [16] Thomas FIM, Cornelisen CD. Ammonium uptake by seagrass communities: Effects of oscillatory versus unidirectional flow. Marine Ecology Progress Series, 2003, 247: 51-57 doi: 10.3354/meps247051 [17] Lowe RJ, Falter JL. Oceanic forcing of coral reefs. Annual Review of Marine Science, 2015, 7: 43-66 doi: 10.1146/annurev-marine-010814-015834 [18] Cheng PD, Zhu HW, Fan JY, et al. Numerical research for contaminant release from un-suspended bottom sediment under different hydrodynamic conditions. Journal of Hydrodynamics, 2013(4): 620-627 [19] 樊靖郁, 陈春燕, 赵亮等. 床面粗糙度和底床渗透率对泥-水界面物质交换特性的影响. 水科学进展, 2020, 31: 232-239 doi: 10.14042/j.cnki.32.1309.2020.02.009Fan Jingyu, Chen Chunyan, Zhao Liang, et al. Impact of bed roughness and sediment permeability on mass exchange across sediment-water interface. Advance in Water Science, 2020, 31: 232-239 (in Chinese) doi: 10.14042/j.cnki.32.1309.2020.02.009 [20] Germano, M, Piomelli U, Moin P, et al. A dynamic subgrid-scale eddy viscosity model. Physics of Fluids A, 1991, 3(7): 1760-1760 doi: 10.1063/1.857955 [21] Dong YH, Lu XY, Zhuang LX. Large eddy simulation of turbulent channel flow with mass transfer at high-Schmidt numbers. International Journal of Heat and Mass Transfer, 2003, 46(9): 1529-1539 doi: 10.1016/S0017-9310(02)00456-8 [22] Whitaker S. Advances in theory of fluid motion in porous media. Industrial and Engineering Chemistry, 1969, 61(12): 14-28 doi: 10.1021/ie50720a004 [23] Nithiarasu P, Seetharamu KN, Sundararajan T. Natural convective heat transfer in a fluid saturated variable porosity medium. International Journal of Heat and Mass Transfer, 1997, 40(16): 3955-3967 doi: 10.1016/S0017-9310(97)00008-2 [24] Scalo, C, Piomelli, U, Boegman L. Large-eddy simulation of oxygen transfer to organic sediment beds. Journal of Geophysical Research: Oceans, 2012, 117(6) [25] Rosti M, Cortelezzi L, Quadrio M. Direct numerical simulation of turbulent channel flow over porous walls. Journal of Fluid Mechanics, 2015, 784: 396-442 doi: 10.1017/jfm.2015.566 [26] Verzicco R, Orlandi P. A finite-difference scheme for three-dimensional incompressible flows in cylindrical coordinates. Journal of Computational Physics, 1996, 123(2): 402-414 doi: 10.1006/jcph.1996.0033 [27] Kim J, Moin P. Application of a fractional-step method to incompressible Navier-Stokes equations. Journal of Computational Physics, 1985, 59(2): 308-323 doi: 10.1016/0021-9991(85)90148-2 [28] 郑艺君, 李庆祥, 潘明等. 多孔介质壁面剪切湍流速度时空关联的研究. 力学学报, 2016, 48(6): 1308-1318 doi: 10.6052/0459-1879-16-208Zheng Yijun, Li Qingxiang, Pan Ming, et al. Analytical of space-time correlations in porous wall-bounded turbulent shear flows. Chinese Journal of Theoretical and Applied Mechanics, 2016, 48(6): 1308-1318 (in Chinese) doi: 10.6052/0459-1879-16-208 [29] Harlow FH. Numerical calculation of time-dependent viscus incompressible flow of fluid with free surface. Physics of Fluids, 1965, 8: 2182-2189 doi: 10.1063/1.1761178 [30] Moser RD, Kim J, Mansour NN. Direct numerical simulation of turbulent channel flow up to Re τ = 590. Physics of Fluids, 1999, 11(4): 943-945 doi: 10.1063/1.869966 [31] Rosti ME, Brandt L, Pinelli A. Turbulent channel flow over an anisotropic porous wall-drag increase and reduction. Journal of Fluid Mechanics, 2018, 842: 381-394 doi: 10.1017/jfm.2018.152 [32] O'Connor BL, Hondzo M. Dissolved oxygen transfer to sediments by sweep and eject motions in aquatic environments. Limnology and Oceanography, 2008, 53(2): 566-578 doi: 10.4319/lo.2008.53.2.0566 [33] Voermans JJ, Ghisalberti M, Ivey GN. A model for mass transport across the sediment-water interface. Water Resources Research, 2018, 54: 2799-2812 doi: 10.1002/2017WR022418 -
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