Greetings Maria Fernanda,
I built the simple model suggested above to see for myself what it takes to get it to converge. I simplified it even more by making the walls of the container rigid. I could not get it to converge using Standard Earth Gravity so I replaced that with an Acceleration load that begins at 100 mm/s^2 to get convergence started, then ramps the value up to 9800 mm/s^2 which represents the acceleration of Standard Earth Gravity. Ansys 2022 R1 archive.
The next model to investigate is to change the container from rigid to flexible and see what happens. The wall thickness and wall material are easily changed to make it gradually more flexible.