how do i create this geometry in a CAD
 

hello to everybody!

i am interested in creating a cad model of a packed bed reactor for, of course, a cfd simulation. but i have a little problem:
when the tube in filled with catalyst pellets, they make a random distribuition inside this tuburar reactor, as far i know it would require a program like edem, for the dem solution of the paking, but i don´t need that presicion, i´m just looking for a good cad program you could recommend me, to make a fast quasi manual colocation of this pellets of defined shape inside the reactor like they were dropped inside it.

for example like dropping icecubes inside a glass.. how can i manually using a cad program, allocate the cubes inside the container in the fastest way possible, without getting crazy... :D

PD. the reactor is just a cylindrical tube of given lenght.

thank you all!