论双向季节性水流对巴丘的影响和闭塞沙丘的起源

IF 3.1 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Geomorphology Pub Date : 2024-10-30 DOI:10.1016/j.geomorph.2024.109488
Willian R. Assis , Danilo S. Borges , Erick M. Franklin
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引用次数: 0

摘要

我们对季节性水流作用下的巴坎形态动力学进行了研究。为此,我们对暴露在双向流下的水下沙丘进行了颗粒尺度的数值计算,并改变了振荡的角度和频率。结果表明,当振荡频率低于沙丘形成的特征时间的倒数时,沙丘会适应新的流动方向,恢复沙丘形状,同时比单向流动时损失更少的颗粒。频率越高,沙丘的适应时间越短,变得越圆,同时流失的颗粒也越多。对于这两种情况,我们首次展示了沙粒的典型动态(轨迹和力)。特别是,圆形沙丘类似于在火星上观测到的所谓闭塞沙丘,与沙丘的时间尺度相比,火星上的季节具有非常高的频率,这一点与地球不同。我们的研究结果为这种形状提供了可能的解释。
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On the effect of two-direction seasonal flows on barchans and the origin of occluded dunes
We inquire into the morphodynamics of barchans under seasonal flows. For that, we carried out grain-scale numerical computations of a subaqueous barchan exposed to two-directional flows, and we varied the angle and frequency of oscillations. We show that when the frequency is lower than the inverse of the characteristic time for barchan formation, the dune adapts to the new flow direction and recovers the barchan shape while losing less grains than under one-directional flow. For higher frequencies, the dune has not enough time for adaptation and becomes more round while losing more grains. For both cases, we show, for the first time, the typical dynamics of grains (trajectories and forces). In particular, the round barchans are similar to the so-called occluded dunes observed on Mars, where seasons have very high frequencies compared to the dune timescale, different from Earth. Our results represent a possible explanation for that shape.
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来源期刊
Geomorphology
Geomorphology 地学-地球科学综合
CiteScore
8.00
自引率
10.30%
发文量
309
审稿时长
3.4 months
期刊介绍: Our journal''s scope includes geomorphic themes of: tectonics and regional structure; glacial processes and landforms; fluvial sequences, Quaternary environmental change and dating; fluvial processes and landforms; mass movement, slopes and periglacial processes; hillslopes and soil erosion; weathering, karst and soils; aeolian processes and landforms, coastal dunes and arid environments; coastal and marine processes, estuaries and lakes; modelling, theoretical and quantitative geomorphology; DEM, GIS and remote sensing methods and applications; hazards, applied and planetary geomorphology; and volcanics.
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