  Laboratory study was set out to investigate the flow structure and turbulent
kinetic energy ($TKE$) within mangrove forest considering flexible canopies and
rigid stems under various wave conditions. Canopies and stems have different
effects on turbulence generation. The flexible leaves in canopy scale can
promote the dissipation of $TKE$ and the rigid stem scale contribute to the
generation of turbulence. Importantly, the difference of $TKE$ with and without
vegetation, $\Delta TKE$ varied with wave frequency and peaked at 0.833 Hz for
the canopy and vegetation-free upper layer, but increased with wave frequency
in stem scale. Moreover, $TKE$ in mangrove forest increased monotonically with
${u_{w,RMS}}^2$ for each stem density. This study proposed a modified model for
the $TKE$ prediction within canopy scale considering the role of flexible
leaves and rigid stems together. Besides, $TKE/{u_{w,RMS}}^2$ presented a good
correlation with the ratio of wave excursion (${A_w}$) to stem spacing ($S$),
${A_w}$/$S$ and declined rapidly with ${A_w}$/$S$ especially when ${A_w}$/$S$
<0.1 for both stem and canopy scale. This empirical relationship can be a
predictor for $TKE$ within mangrove forest. Further, considering the scale
between wave energy dissipation by vegetation and production of $TKE$, the
third model was validated in mangrove forest and predicted well.
