"Forest density is more effective than tree rigidity at reducing the on" by Abhishek Mukherjee, Juan Carlos Cajas et al.
 

Forest density is more effective than tree rigidity at reducing the onshore energy flux of tsunamis

Document Type

Article

Publication Date

6-1-2023

Abstract

Communities around the world are increasingly interested in nature-based solutions to the mitigation of coastal risks by coastal forests, but it remains unclear how much protective benefits vegetation provides, particularly in the limit of highly energetic flows after tsunami impact. The current study, using a three-dimensional incompressible computational fluid dynamics model with a fluid–structure interaction approach, aims to quantify how energy reflection and dissipation vary with different degrees of rigidity and vegetation density of a coastal forest. We represent tree trunks as cylinders and use the elastic modulus of hardwood trees such as pine or oak to characterize the rigidity of these cylinders. The numerical results show that energy reflection increases with rigidity only for a single cylinder. In the presence of multiple cylinders, the difference in energy reflection created by varying rigidity diminishes as the number of cylinders increases. Instead of rigidity, we find that the blockage area created by the presence of multiple tree trunks dominates energy reflection. As tree trunks are deformed by the hydrodynamic forces, they alter the flow field around them, causing turbulent kinetic energy generation in the wake region. As a consequence, trees dissipate flow energy, highlighting coastal forests reducing the onshore energy flux of tsunamis by means of both reflection and dissipation.

Identifier

85147654920 (Scopus)

Publication Title

Coastal Engineering

External Full Text Location

https://doi.org/10.1016/j.coastaleng.2023.104286

ISSN

03783839

Volume

182

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