發(fā)布時(shí)間：2017-12-27 07:22

  本文關(guān)鍵詞：長江河口北槽彎道橫向次生流、混合與層化　出處：《海洋工程》2016年03期 　論文類型：期刊論文

  更多相關(guān)文章： 長江河口 北槽彎道 次生流 混合 層化 勢能差異 應(yīng)變

【摘要】：2013年2月25至26日(枯季/大潮)、7月23至24日(洪季/大潮)分別在長江河口北槽彎道沿著3條橫向測線CS6、CSW和CS3(每條測線上有北、中、南3個(gè)站位)測得水位、流速、鹽度和含沙量的時(shí)間序列資料。通過這些資料的定量計(jì)算、分析,理解彎道橫向次生流、混合與層化的時(shí)、空變化和各種物理機(jī)制及其相對(duì)重要性。3條橫向測線均存在橫向次生流,且橫向測線CS3還出現(xiàn)橫向次生環(huán)流。枯、洪季,僅在橫向測線CS6、CS3出現(xiàn)環(huán)狀歐拉余流。枯、洪季,沿著橫向測線CS3,3個(gè)站位的橫向斜壓梯度比離心加速度和科氏加速度都大1~2個(gè)數(shù)量級(jí),而后兩項(xiàng)大小接近且數(shù)量級(jí)都是10-4,羅斯貝數(shù)在1左右。這些表明:橫向次生流受橫向斜壓梯度、離心加速度和科氏加速度共同驅(qū)動(dòng),前一項(xiàng)相對(duì)于后兩項(xiàng)更加重要。沿著3條橫向測線:1)枯、洪季大潮,平均勢能差異分別約為54.23、66.56 J/m3,表明洪季層化強(qiáng)于枯季;2)枯季漲潮,平均的勢能差異普遍小于落潮,而洪季漲潮,平均的勢能差異普遍大于落潮,表明枯、洪季湍流混合均存在潮汐不對(duì)稱性;3)枯季,由橫向、縱向水深平均應(yīng)變(ΦS-y、ΦS-x)引起的勢能差異變化率的范圍分別是-67×10~(-3)~37×10~(-3)、-7×10~(-3)~11×10~(-3)W/m~3,而洪季,相應(yīng)的范圍分別是-45×10~(-3)~30×10~(-3)、-14×10~(-3)~13×10~(-3)W/m~3,表明枯、洪季差異不明顯,橫向水深平均應(yīng)變(ΦS-y)均大于縱向水深平均應(yīng)變(ΦS-x),前項(xiàng)對(duì)水體混合與層化的影響更大;4)枯季大潮,縱向平流(ΦA(chǔ)-x)、橫向平流(ΦA(chǔ)-y)、縱向水深平均應(yīng)變(ΦS-x)和橫向水深平均應(yīng)變(ΦS-y)的潮汐平均絕對(duì)值占四項(xiàng)總和之比例分別為26%、33%、18%和23%,而洪季大潮,相應(yīng)的值的比例分別為13%、9%、22%和56%,表明枯季,平流項(xiàng)(ΦA(chǔ)-y最大)對(duì)混合與層化的控制可能占主導(dǎo)地位;洪季,應(yīng)變項(xiàng)(ΦS-y最大)可能占主導(dǎo)地位。無量綱數(shù)(m)被用于判別橫向平流(ΦA(chǔ)-y)、橫向水深-平均應(yīng)變(ΦS-y)的相對(duì)重要性。一個(gè)概念性模式被用于顯示層化與橫向次生流/環(huán)流的相互關(guān)系。
[Abstract]:From 25 to 26 February 2013 (dry season / spring tide) and 23 to 24 days in July (flood season / spring tide), the time series data of water level, velocity, salinity and sediment concentration were measured along the North Bend of the Yangtze River Estuary along the 3 horizontal lines CS6, CSW and CS3 (each station has 3 stations in North, middle and South). Through the quantitative calculation and analysis of these data, we can understand the temporal and spatial variation of the lateral stream, mixing and stratification, and the various physical mechanisms and their relative importance. The transverse secondary current exists in all 3 transverse lines, and the transverse secondary circulation is also appeared in the lateral line CS3. In the dry and flood season, the annular Eulerian residual current appeared only on the horizontal line CS6 and CS3. In the dry season and the flood season, the lateral baroclinic gradient along the transverse line CS3,3 stations is 1~2 orders of magnitude larger than the centrifugal acceleration and Coriolis acceleration. The latter two items are close to the magnitude and the order of magnitude is 10-4, and Ross Bbe Gh is around 1. These results show that the transverse secondary flow is driven by the transverse baroclinic gradient, the centrifugal acceleration and the Coriolis acceleration, and the first one is more important than the latter two. 娌跨潃3鏉℃í鍚戞祴綰，

本文編號(hào)：1340767