Solitary wave attenuation by vegetation patches

• Published in: Advances in water resources 2016-12, Vol.98, p.159-172
• Main Authors: Maza, Maria, Lara, Javier L., Losada, Iñigo J.
• Format: Article
• Language: English
• Subjects: Capacity; Computational fluid dynamics; Computer simulation; Configurations; Correlation analysis; Cylinders; Dimensions; Fluid flow; Forces (mechanics); Mathematical analysis; Mathematical models; Navier-Stokes equations; Parameters; Patches (structures); Patchiness; Propagation; Reynolds number; Solitary wave; Solitary waves; Submergence; Vegetation; Vegetation effects; Vegetation patches; Water column; Water depth; Wave attenuation; Wave attenuation wave-exerted forces; Wave forces; Wave number; Wave period; Wave propagation
• ISSN: 0309-1708; 1872-9657
• DOI: 10.1016/j.advwatres.2016.10.021

•A new parameterization that accounts for the effect of vegetation patchiness in wave height attenuation is presented.•Higher relative wave heights and submergence ratios lead to bigger wave attenuation rates.•New non-dimensional parameters that account for flow and vegetation characteristics allow founding common fittings for the wave attenuation induced by different vegetation patchiness.•Analyzed wave height patterns and wave-exerted forces highlight the differences obtained for one continuous field and one built using patches. The effect of vegetation patchiness on solitary wave propagation, attenuation and wave-induced forces is studied both experimentally and numerically. Vegetation patchiness is simulated with rigid cylinder configurations built by one, eight and four patches tested under emergent, near emergent and submerged conditions. These configurations are parameterized by means of a new parameter (equivalent length, Le), which is used to relate cylinders distribution with wave attenuation capacity. This new parameter allows comparing results for the three patches configurations. Larger attenuation rates are found for higher wave heights and shorter wave periods. The influence of water depth is also considered by means of the submergence ratio (SR) in order to account for the percentage of water column affected by vegetation. Higher attenuation rates are obtained for emergent conditions. High correlations are found between wave attenuation and a new set of parameters, the depth wave number (kLe × SR), that accounts for submergence conditions and field characteristics and a new Reynolds number (ResLe), that is calculated considering the field vegetation dimensions affecting the flow. Experimental results are extended using IHFOAM, a three dimensional Navier-Stokes equations solver, to analyze wave forces on individual cylinders and wave propagation patterns showing the variability of forces magnitude and direction associated to vegetation patchiness.