Plate-like regime of a numerically modeled thermal convection in a fluid with temperature-, pressure-, and stress-history-dependent viscosity
Plate-like regime of a numerically modeled thermal convection in a fluid with temperature-, pressure-, and stress-history-dependent viscosity
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具有与温度、压力和应力历史相关的粘度的流体中数值模拟的热对流的板状状态
DOI：
10.1029/2000jb000069
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发表时间：
2003
影响因子：
--
通讯作者：
Masaki Ogawa
中科院分区：
文献类型：
--
作者：
Masaki Ogawa
[1]建立了一系列二维热对流的数值模型，该模型的粘性与“损伤度”ω以及温度和压力呈非线性关系;当对流引起强粘性耗散时，ω随时间增加，粘性随时间减小。对流流体以取决于温度的特征时间从损伤中恢复。粘度的ω依赖性引起应力-粘度关系，其由两个分支组成，在低应力下的“完整分支”和在高应力下的“受损分支”，在两个分支之间具有滞后;在完整（受损）分支上，ω小（大）且粘度高（低）。滞后使粘度取决于应力历史。粘度对应力历史的依赖性，由于滞后引起的制度，其中数值模拟的岩石圈沿着表面边界被分割成较小的块，是在完整的分支和刚性移动。岩石圈的碎片被狭窄的机械薄弱区隔开，这些薄弱区位于受损的分支上。岩石圈的每一块都进一步破碎，只有当这块岩石被特别强烈的热上升羽流敲击时，机械薄弱区才新形成。这种“板状”状态是唯一的状态，在这里搜索的对流状态，其中每一块岩石圈刚性移动，仍然没有破裂的力量，驱动件。地球的地幔被认为是在板块状制度。
[1] A series of numerical models are presented for two-dimensional thermal convection in a fluid with viscosity that nonlinearly depends on “degree of damage” ω as well as temperature and pressure; ω increases and viscosity decreases with time when the convection induces strong viscous dissipation. The convecting fluid recovers from the damage with a characteristic time that depends on temperature. The ω dependence of viscosity induces a stress-viscosity relationship that consists of two branches, the “intact branch” at low stress and the “damaged branch” at high stress, with a hysteresis between the two branches; ω is small (large) and viscosity is high (low) on the intact (damaged) branch. The hysteresis lets the viscosity depend on stress history. The dependence of viscosity on stress history due to the hysteresis induces a regime where the numerically modeled lithosphere along the surface boundary is fragmented into smaller pieces that are on the intact branch and rigidly move. The pieces of lithosphere are separated by narrow mechanically weak zones that are on the damaged branch. Each piece of lithosphere is further fragmented and mechanically weak zones are newly formed only when the piece is tapped by particularly strong hot uprising plumes. This “plate-like” regime is the only regime, among the convective regimes searched here, where each piece of lithosphere rigidly moves and still is not ruptured by the forces that drive the piece. The Earth's mantle is suggested to be on the plate-like regime.