Vial geometries for optimal mixing

A vial assembly, comprising:

• a vial comprising a particulate material, a septum, a neck region including a first width, and a particulate region including a second width greater than the first width;
• and
• a needle comprising at least one port;
• wherein the vial assembly is configured to move to a locked position;
• wherein the needle is configured to puncture the septum of the vial assembly when the vial assembly is in the locked position;
• wherein the at least one port is further configured to be in the neck region of the vial assembly so as to face a side wall of the neck region when the vial assembly is in the locked position;
• and
• wherein the at least one port is configured to inject a fluid into the vial assembly to mix with the particulate material upon actuation of a vial engagement mechanism in a first direction and to receive a resulting mixed fluid from the vial assembly upon actuation of the vial engagement mechanism in a second direction opposite the first direction;
• wherein the vial comprises an external wall including (i) a distal sidewall disposed along a plane coaxial with a longitudinal axis of the vial assembly and terminating at a distal end of the vial and (ii) a proximal sidewall disposed along the plane and terminating at a proximal end of the vial, the distal side wall comprising a particulate region thickness between the external wall and the particulate region, and the proximal sidewall comprising a neck region thickness between the external wall and the neck region, wherein the neck region thickness of the proximal sidewall is greater than the particulate region thickness of the distal sidewall.