Evolution of the Angular Momentum during Gravitational Fragmentation of Molecular Clouds*

We investigate the origin of observed scaling $j\sim R^{3/2}$ between specific angular momentum $j$ and radius $R$ molecular clouds (MCs) their substructures, near independence $\beta$, ratio rotational to gravitational energy, from $R$. To this end, we measure (AM) sets particles in an SPH simulation formation, collapse fragmentation giant MCs. The are defined either as ``clumps'' (connected particle sets), or lagrangian that conform a connected clump only at certain time $\tdef$. find that: {\it i)} Clumps evolve along \jR\ relation all times, ii)} Lagrangian when volume containing them also contains large number other ``intruder'' particles. Otherwise, they with $j\sim$ cst. iii)} Tracking future, subset participates collapse, while another disperses away. iv)} Noting that, under AM conservation, $\beta$ increases during contraction, suggest its may arise competition increase exchange rate higher energy density gradient. v)} if MCs globally dominated by gravity, arises because observational selection dense structures amounts selecting fragments have lost via Reynolds stresses neighbors.