Wave and bed-friction effect on instability of shear flow in shallow waters

2020 ◽  
pp. 60-67
Author(s):  
Boyuan Yu ◽  
Vincent H. Chu
Keyword(s):  
Shear Flow ◽  
Shallow Waters ◽  
Friction Effect ◽  
Bed Friction

scholarly journals The role of waves on mixing in shallow waters

2019 ◽  
Vol 46 (2) ◽  
pp. 134-147 ◽  
Author(s):  
Shooka Karimpour ◽  
Vincent H. Chu
Keyword(s):  
Shock Waves ◽  
Shear Flow ◽  
Froude Number ◽  
Structural Changes ◽  
Mixing Layer ◽  
Vortex Sheet ◽  
Layer Growth ◽  
Shallow Waters ◽  
Critical Range

The role of waves on mixing is examined in a transverse shear flow in shallow waters for sub-critical, trans-critical, and super-critical flow over a range of convective Froude numbers. At low convective Froude numbers, the rollup of the vortex sheet to form an eddy defines the mixing. The mixing at higher convective Froude numbers, on the other hand, is affected by the shock waves and the radiation of the wave energy from an elongated vorticity element. Significant structural changes of the shear flow occur as the shock waves become discernible in the trans-critical and super-critical range of the convective Froude number. The shear layer growth is restrained while the momentum-thickness to vorticity-thickness ratio increases by a factor greater than 3. The fractional growth rate of the mixing layer in shallow waters and its dependence on the convective Froude number follows analogously the observed Mach-number dependence in gas dynamics.

Pemetaan Pulau Kecil Gelasa Kabupaten Bangka Tengah

2019 ◽  
Vol 2 (1) ◽  
pp. 11-14
Author(s):  
Wahyu Adi
Keyword(s):  
Coral Reefs ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Image Interpretation ◽  
Vegetation Coverage ◽  
Small Island ◽  
Shallow Waters ◽  
Small Islands ◽  
Seagrass Beds ◽  
Cover Density

Pulau Kecil Gelasa merupakan daerah yang belum banyak diteliti. Pemetaan ekosistem di pulau kecil dilakukan dengan bantuan citra Advanced Land Observing Satellite (ALOS). Penelitian terdahulu diketahui bahwa ALOS memiliki kemampuan memetakan terumbu karang dan padang lamun di perairan dangkal serta mampu memetakan kerapatan penutupan vegetasi. Metode interpretasi citra menggunakan alogaritma indeks vegetasi pada citra ALOS yaitu NDVI (Normalized Difference Vegetation Index), serta pendekatan Lyzengga untuk mengkoreksi kolom perairan. Hasil penelitian didapatkan luasan Padang Lamun di perairan dangkal 41,99 Ha, luasan Terumbu Karang 125,57 Ha. Hasil NDVI di daratan/ pulau kecil Gelasa untuk Vegetasi Rapat seluas 47,62 Ha; luasan penutupan Vegetasi Sedang 105,86 Ha; dan penutupan Vegetasi Jarang adalah 34,24 Ha.   Small Island Gelasa rarely studied. Mapping ecosystems on small islands with the image of Advanced Land Observing Satellite (ALOS). Previous research has found that ALOS has the ability to map coral reefs and seagrass beds in shallow water, and is able to map vegetation cover density. The method of image interpretation uses the vegetation index algorithm in the ALOS image, NDVI (Normalized Difference Vegetation Index), and the Lyzengga approach to correct the water column. The results of the study were obtained in the area of Seagrass Padang in the shallow waters of 41.99 ha, the area of coral reefs was 125.57 ha. NDVI results on land / small islands Gelasa for dense vegetation of 47.62 ha; area of Medium Vegetation coverage 105.86 Ha; and the coverage of Rare Vegetation is 34.24 Ha.

Solidification of a binary mixture in a shear flow

2002 ◽  
Author(s):  
Sophie Mergui ◽  
Boubaker Feroual ◽  
Christine Benard ◽  
Dominique Gobin
Keyword(s):  
Shear Flow ◽  
Binary Mixture
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