I am solving this equation with ode45 method, $p_0$ is already known:
$4B\dfrac{d^2u}{dr^2}+\dfrac{4B}{r}\dfrac{du}{dr}=\dfrac{dp_0}{dz}$
and I have two conditions,
initial condition: $r=0$: $\dfrac{du}{dr}=0$;
boundary condition where $r=1$: $u=0$.
Where to put these conditions, because I can put initial condition in ode45 solver, but where to put boundary condition in this case?