  Solutions to the Schr\"{o}dinger equation are examined for a particle inside
a cylindrical trap of a circular time-dependent cross-section. Analytical
expressions for energy and momentum expectation values are derived with respect
to the exact solutions; and the adiabatic and sudden change of the boundary are
discussed. The density profile as a function of time in a given observation
point, resembles the diffraction-in-time pattern observed in a suddenly
released particle but with an enhanced fringe visibility. Numerical
computations are presented for both contracting and expanding boxes.
