(Received 25 January 2012; revised manuscript received 12 July 2012; published 27 August 2012)We study dissipation and relaxation processes within the time-dependent Hartree-Fock approach using theWigner distribution function. On the technical side we present a geometrically unrestricted framework whichallows us to calculate the full six-dimensional Wigner distribution function. With the removal of geometricalconstraints, we are now able to extend our previous phase-space analysis of heavy-ion collisions in the reactionplane to unrestricted mean-field simulations of nuclear matter on a three-dimensional Cartesian lattice. Fromthe physical point of view we provide a quantitative analysis on the stopping power in TDHF. This is linkedto the effect of transparency. For the medium-heavy