Several different cases of amplitude blowup in compressible Euler flows are known: Guderley's and Sedov's imploding shock solutions, Hunter's collapsing cavity, as well as more recently constructed continuous/smooth implosions. It is natural to ask if these flows provide worst case scenarios, or if something essentially worse can occur in Euler flows.

We shall review the (well-known) class of ``affine'' flows and observe that these provide examples of accumulation, i.e., the generation of a Dirac delta in the density field. On the other hand, it appears that all known examples of this type suffer from certain un-physical features related to far-field behavior.

We will discuss these, provide examples, and consider the possibility of constructing ``acceptable'' examples of accumulating flows.