Part $1$ of $3-$ Drinking Straw Insertion

A drinking straw is inserted horizontally into a stagnant lemonade juicebox at a velocity $V.$

Question $3$ of $9$

Mark each of the following which would be appropriate spatial boundary conditions to properly model the motion inside the straw.

A$.$ At $t=0,v_z=0.$

B$.$ At $r=R,v_z=V.$

C$.$ As $r$ infinity, $v_z=0.$

D$.$ At the center of the straw, the velocity profile is symmetric. Thus, at $r=0,$del$\frac{v_z}{d}$elr$=0.$

E$.$ None of the above.