| dbo:abstract |
An antidune is a bedform found in fluvial and other channeled environments. Antidunes occur in supercritical flow, meaning that the Froude number is greater than 1.0 or the flow velocity exceeds the wave velocity; this is also known as upper flow regime. In antidunes, sediment is deposited on the upstream (stoss) side and eroded from the downstream (lee) side, opposite lower flow regime bedforms. As a result, antidunes migrate in an upstream direction, counter to the current flow. Antidunes are called in-phase bedforms, meaning that the water surface elevation mimics the bed elevation; this is due to the supercritical flow regime. Antidune bedforms evolve rapidly, growing in amplitude as they migrate upstream. The resultant wave at the water's surface also increases in amplitude. When that wave becomes unstable, breaks and washes downstream, much of the antidune bedform may be destroyed. (en) 反砂堆（はんさたい）またはアンチデューン（英語: Antidune）とは、その波長や波高が水深のスケールに規定される、（）のひとつである。砂堆とは異なり、河川の流れが平均的に射流で、フルード数がある臨界値を超える場合に河床に形成される。反砂堆では水流が剥離することがほとんどなく、そのため形状はクレスト（峰）を中心に左右対称のなめらかな波形となる。また反砂堆のは一般に非定常性が強く、発達と減衰を繰り返すことがある。 反砂堆は、砂堆とは異なり、ほとんどの場合、上流側へ伝播する。これは、クレストを過ぎた下流側斜面で砂が活発に移動し、上流側斜面では砂が堆積するためである。 (ja) 逆行沙丘（英語：antidune）是一種在河流和其他渠道環境中的沙丘狀層面。逆行沙丘發生在超界流中，即福祿數數大於1.0或流速超過波速。在逆行沙丘中，沉積物沉積在上游（英語：stoss）側並從下游（英語：lee）側被侵蝕，與沙丘相反。逆行沙丘向上游方向遷移，與沙丘亦相反。逆行沙丘被稱為同相河床，亦即水面高低與河床高低相似。反沙丘向上游遷移時，振幅增加。水面上的合成波的振幅也會增加。當水面波浪變得不穩定、垮塌后並沖向下游時，大部分反沙丘亦被破壞。 (zh) |
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wiki-commons:Special:FilePath/AntidunesInASmallStream.jpg?width=300 |
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http://jsedres.sepmonline.org/cgi/content/abstract/35/4/922 https://web.archive.org/web/19980128104006/http:/encyclopedia.com/ https://web.archive.org/web/20080908004604/http:/radio.weblogs.com/0100021/categories/antidunes/2002/06/13.html https://web.archive.org/web/20081011003303/http:/radio.weblogs.com/0100021/stories/2002/03/06/sedimentTransportInAntidun.html https://web.archive.org/web/20110710201132/http:/fluidflow.es-designs.com/%3Fp=150 https://web.archive.org/web/20110710201620/http:/fluidflow.es-designs.com/%3Fp=155 https://web.archive.org/web/20110710201702/http:/fluidflow.es-designs.com/%3Fp=159 https://web.archive.org/web/20110710201741/http:/fluidflow.es-designs.com/%3Fp=219 https://www.youtube.com/watch%3Fv=81t8u15aNXs |
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反砂堆（はんさたい）またはアンチデューン（英語: Antidune）とは、その波長や波高が水深のスケールに規定される、（）のひとつである。砂堆とは異なり、河川の流れが平均的に射流で、フルード数がある臨界値を超える場合に河床に形成される。反砂堆では水流が剥離することがほとんどなく、そのため形状はクレスト（峰）を中心に左右対称のなめらかな波形となる。また反砂堆のは一般に非定常性が強く、発達と減衰を繰り返すことがある。 反砂堆は、砂堆とは異なり、ほとんどの場合、上流側へ伝播する。これは、クレストを過ぎた下流側斜面で砂が活発に移動し、上流側斜面では砂が堆積するためである。 (ja) 逆行沙丘（英語：antidune）是一種在河流和其他渠道環境中的沙丘狀層面。逆行沙丘發生在超界流中，即福祿數數大於1.0或流速超過波速。在逆行沙丘中，沉積物沉積在上游（英語：stoss）側並從下游（英語：lee）側被侵蝕，與沙丘相反。逆行沙丘向上游方向遷移，與沙丘亦相反。逆行沙丘被稱為同相河床，亦即水面高低與河床高低相似。反沙丘向上游遷移時，振幅增加。水面上的合成波的振幅也會增加。當水面波浪變得不穩定、垮塌后並沖向下游時，大部分反沙丘亦被破壞。 (zh) An antidune is a bedform found in fluvial and other channeled environments. Antidunes occur in supercritical flow, meaning that the Froude number is greater than 1.0 or the flow velocity exceeds the wave velocity; this is also known as upper flow regime. In antidunes, sediment is deposited on the upstream (stoss) side and eroded from the downstream (lee) side, opposite lower flow regime bedforms. As a result, antidunes migrate in an upstream direction, counter to the current flow. Antidunes are called in-phase bedforms, meaning that the water surface elevation mimics the bed elevation; this is due to the supercritical flow regime. Antidune bedforms evolve rapidly, growing in amplitude as they migrate upstream. The resultant wave at the water's surface also increases in amplitude. When that (en) |
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Antidune (en) 反砂堆 (ja) 逆行沙丘 (zh) |
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