الفهرس 
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Abstract
A breakwater consists of staggered hollow artificial shells based on rubble mound base is proposed as a new type of breakwaters through this study. This type is chosen according to its features, like shape which could smoothly disperse incident waves by wave climbs and penetration through shells gaps. These gaps will facilitate water exchanging between sea and protected area, especially for tourist beaches. It also observed that the shells length, width are almost twice the shell height which could be increased shells stability against high wave action. The proposed breakwater is checked using four water depths to investigate it in, emerged, partially submerged, submerged, and fully submerged cases. The efficiency of the proposed breakwater is presented in terms of wave reflection coefficient (Kr), wave transmission coefficient (Kt), and wave dissipation coefficient (Kd). Also, wave run-up and wave run-down for the partially submerged case are introduced. In case of emerged case, for relative wavelength (h/L) ranging from 0.060 to 0.128, reflection, transmission, dissipation coefficients are 60 to 30 %, 27 to 17 %, and 75 to 93% respectively. For partially submerged case, relative wavelength (h/L) ranges from 0.07 to 0.15. Reflection, transmission, dissipation coefficients range from 48 to 16 %, 47 to 30 %, and 75 to 93% respectively. For submerged case, relative wavelength (h/L) ranges from 0.079 to 0.177. Reflection, transmission, dissipation coefficients range from 15 to 45 %, 38 to 63 %, and 69 to 88% respectively. For fully submerged case, relative wavelength (h/L) ranges from 0.09 to 0.175. Reflection, transmission, dissipation coefficients range from 10 to 34 %, 71 to 89 %, and 40 to 65% respectively. Wave run-up and wave run-down for the partially submerged case are decreased with increasing relative wavelength. Finally, a partially submerged case that shows the better efficiency among other configuration is compared with some of the widely used breakwaters. This comparison revealed that, convergent reflection values for relative wavelength ( ℎ𝐿<0.09 ). But in the case of relative wavelength ( ℎ𝐿≥0.09 ) the artificial shells breakwater shows lower values of the reflection coefficient. In the case of wave transmission coefficient (Kt), it is observed that inverse relationship between artificial shells breakwater and other traditional types except for suspended C shape breakwater. The dissipation coefficient increased with wavelength decrease for all types of breakwaters. But in the case of artificial shells breakwater, the dissipation coefficient rate are higher than other types of breakwaters, especially for short wavelength.