From the energy functional, we can derive the Euler-Lagrange equation and its corresponding gradient flow equation. My question is, what is the physical unit for ``time'' in the gradient flow equation?

For example, the Oseen-Frank energy for liquid crystal is given by $$\int_{\Omega} \frac{1}{2} K |\nabla u|^2,$$ where $u$ is the angle of the director with the $x$-axis, and $K$ is an elastic constant with unit Newton. The corresponding gradient flow equation is $$\frac{\partial u}{\partial t} = K \triangle u.$$ But then what is the unit of time $t$? It seems that it does not have the unit of time. What am I missing here?

Thanks!