On the stability of tracer simulations with opposite-signed diffusivities
On the stability of tracer simulations with opposite-signed diffusivities
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关于具有相反符号扩散率的示踪剂模拟的稳定性
DOI：
10.1017/jfm.2022.126
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发表时间：
2022
影响因子：
3.7
通讯作者：
Haigh M
中科院分区：
文献类型：
--
作者：
Haigh M
最近的许多研究已经诊断相反签署的扩散本征值是一个普遍的特征的传输张量的扩散示踪剂输送的海洋中尺度涡旋。这个诊断张量，我们称之为扩散张量，因此占示踪剂的扩散效应。该取向的优先取向由扩散张量的主轴，即扩散轴来量化。涡流扩散的参数化通常调用扩散张量，通常具有非负特征值以避免数值问题。出于需要参数化的示踪剂rectenation，在这项研究中，我们研究扩散的高斯示踪剂补丁施加相反签署的扩散特征值，特别是我们专注于不稳定的发病时间尺度。对于一个固定的扩散轴，数值不稳定性是一个不可避免的后果，持续上升梯度通量与负特征值。对于典型的海洋尺度和扩散量级，这个时间尺度是天的数量级，但更短的负特征值或更精细的网格分辨率。我们表明，施加一个随时间变化的扩散轴可以导致模拟没有发生不稳定后，100 000天的示踪剂演变。虽然海洋流体动力学的动机，我们的研究结果有更广泛的应用，因为扩散过程中存在广泛的流体流动。
Many recent studies have diagnosed opposite-signed diffusion eigenvalues to be a prevalent feature of the transfer tensor for diffusive tracer transport by oceanic mesoscale eddies. This diagnosed tensor, which we refer to as the diffusion tensor, therefore accounts for tracer filamentation effects. The preferential orientation of this filamentation is quantified by the principal axis of the diffusion tensor, namely the diffusion axis. Parameterisations of eddy diffusion commonly invoke a diffusion tensor, typically one with non-negative eigenvalues to avoid numerical issues. Motivated by the need to parameterise tracer filamentation, in this study we examine diffusion of a Gaussian tracer patch with imposed opposite-signed diffusion eigenvalues, and in particular we focus on the time scale for the onset of instability. For a fixed diffusion axis, numerical instability is an inevitable consequence of persistent up-gradient fluxes associated with the negative eigenvalue. For typical oceanic scales and diffusion magnitudes, this time scale is of the order of days, but is shorter for larger negative eigenvalues or for finer grid resolutions. We show that imposing a time-dependent diffusion axis can lead to simulations with no onset of instability after 100 000 days of tracer evolution. Although motivated by oceanographic fluid dynamics, our results have much broader applications since diffusive processes are present in a wide range of fluid flows.
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影响因子：
6.8
作者：
S. Bachman;B. Fox‐Kemper;F. Bryan
通讯作者：
S. Bachman;B. Fox‐Kemper;F. Bryan
影响因子：
3.2
作者：
M. Haigh;Luolin Sun;J. McWilliams;P. Berloff
通讯作者：
M. Haigh;Luolin Sun;J. McWilliams;P. Berloff
海洋中尺度涡扩散率的复杂性
影响因子：
5.2
作者：
Kamenkovich, Igor;Berloff, Pavel;Haigh, Michael;Sun, Luolin;Lu, Yueyang
通讯作者：
Lu, Yueyang
影响因子：
3.2
作者：
M. Haigh;Luolin Sun;J. McWilliams;P. Berloff
通讯作者：
M. Haigh;Luolin Sun;J. McWilliams;P. Berloff
影响因子：
3.2
作者：
M. Haigh;P. Berloff
通讯作者：
M. Haigh;P. Berloff