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Laboratory study of the effects of terrestrial coastal forests on the absorption of solitary wave force

Mirzakhani Golnaz, Ghanbari-Adivi Elham, Fattahi Rohollah

Acta Geophysica

2024

Vol. 72, no. 1

449--465

One of the beach protection techniques is using natural methods based on the coastal ecosystem. Studies show the reducing effect of forest covers on wave destruction intensity in different areas. However, it is not yet well understood how various densities of terrestrial coastal forest (TCF) affect the wave attenuation and reduce their strength. Studying the impact of various forest parameters, such as density, distance, and arrangement type on the wave force attenuation, this research measures the wave forces directly. TCF model was installed in a knife edge flume, which equipped with a load cell and an acoustic Doppler velocimeter. The experiments were performed in two staggered and parallel arrangements consisting of different densities from 12 to 273 stems per unit area. Based on obtained results, TCF had significant effects on the wave force absorption. An increase in the number of trees (density) increased TCF resistance force and the absorbed wave force. In its best, the TCF could absorb the wave force 3.76 times more than the no-TCF case. It could reduce the wave height by up to 81% at the highest density and maximum wave height. The absorbed wave force and drag coefficient rose as the number of rows of trees opposing the flow decreased and the intervals between trees were shortened. Increasing tree density from 12 to 273 stems per unit area increased the drag coefficient by the average of 61.82% for parallel and staggered arrangements, which means an average increase of 9.7% for each TCF row.

Metoda formułowania modelu dynamicznego mobilnego systemu obrony nadbrzeżnej

Dziopa Z.

Zeszyty Naukowe Akademii Marynarki Wojennej

2009

R. 50 nr 177B

49-58

W pracy przedstawiona jest metoda energetyczna formułowania mobilnego systemu obrony nadbrzeżnej. Ruch układu rozpatrywany jest w trójwymiarowej przestrzeni Euklidesa. Rozważane są drgania o dużych wartosciach przemieszczeń uogólnionych poszczególnych obiektów, stanowiących dyskretny model układu. Celem pracy jest zaprezentowanie ogólnej metodologii wyprowadzenia modelu matematycznego i zastosowanie jej do sformułowania równań ruchu układu w przypadku przyjęcia założeń upraszczających.

The paper presents the energetic method of formulating a mobile coastal defence system. The system movement is discussed within the Euclidean tri-dimensional space. The vibrations considered are those with high values of generalized relocations for individual objects constituting a discrete system model. The aim of the paper is to present the general methodology of mathematical model introduction and its application in formulating the system movement equations in the case of simplified assumptions.