文章基本信息

标题：Entrainment in Temporally Evolving Turbidity Currents
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作者：Jorge S. Salinas ; Mariano I. Cantero ; Mrugesh Shringarpure 等
期刊名称：Mecánica Computacional
印刷版ISSN：2591-3522
出版年度：2017
卷号：35
期号：19
页码：1105-1105
语种：English
出版社：CIMEC-INTEC-CONICET-UNL
摘要：Turbidity currents are sediment laden shear ﬂows that run along a sloping bed, often submerged beneath a deep layer of quiescent ﬂuid, driven by the excess hydrostatic pressure due to the suspended sediments. Turbidity currents are always turbulent since the suspended sediment particles that drive the ﬂow cannot remain in suspension under laminar conditions. As the turbidity current travels downslope, the ﬂow interacts with the bed at the bottom and with the ambient ﬂuid layer at the top. Ambient ﬂuid entrainment is a fascinating ﬂuid mechanical phenomenon where quiescent ambient ﬂuid is ingested into the current to an active shear ﬂow. As the turbidity current ﬂows downstream over the sloping bed, under a deep ambient of clear ﬂuid, clear ambient ﬂuid is continuously entrained into the turbidity current and the thickness of the current increases. In this work we study the entrainment mechanism taking place between the ambient ﬂuid layer and the turbidity current by means of fully resolved direct numerical simulations. Entrainment is a function of both the local Richardson number, Ri, and the non-dimensional settling velocity of the sediments. Here we consider a model turbidity current that is homogeneous in the streamwise direction. Thus, the effect of entrainment of clear ﬂuid at the top of the turbidity current results in a temporal growth of the current height. With the assumption of streamwise homogeneity we investigate a non-stationary problem where the temporal growth of the height of the turbidity current is monitored in order to evaluate the role of entrainment of clear ﬂuid.
其他摘要：Turbidity currents are sediment laden shear ﬂows that run along a sloping bed, often submerged beneath a deep layer of quiescent ﬂuid, driven by the excess hydrostatic pressure due to the suspended sediments. Turbidity currents are always turbulent since the suspended sediment particles that drive the ﬂow cannot remain in suspension under laminar conditions. As the turbidity current travels downslope, the ﬂow interacts with the bed at the bottom and with the ambient ﬂuid layer at the top. Ambient ﬂuid entrainment is a fascinating ﬂuid mechanical phenomenon where quiescent ambient ﬂuid is ingested into the current to an active shear ﬂow. As the turbidity current ﬂows downstream over the sloping bed, under a deep ambient of clear ﬂuid, clear ambient ﬂuid is continuously entrained into the turbidity current and the thickness of the current increases. In this work we study the entrainment mechanism taking place between the ambient ﬂuid layer and the turbidity current by means of fully resolved direct numerical simulations. Entrainment is a function of both the local Richardson number, Ri, and the non-dimensional settling velocity of the sediments. Here we consider a model turbidity current that is homogeneous in the streamwise direction. Thus, the effect of entrainment of clear ﬂuid at the top of the turbidity current results in a temporal growth of the current height. With the assumption of streamwise homogeneity we investigate a non-stationary problem where the temporal growth of the height of the turbidity current is monitored in order to evaluate the role of entrainment of clear ﬂuid.