NewTest

\begin{equation} \tag{87}

 \text{Ribberink (1998)}\Phi (t)=11{ {(\left| {{\theta }_{w}}(t) \right| -{{\theta }_{cr}})}^{1.65}}\frac{{{\theta }_{w}}(t)}{\left| {{\theta }_{w}}(t) \right|}

\end{equation}

${\displaystyle }$