Amplitude blowup in compressible Euler flows without shock formation

Recent works have demonstrated that continuous self-similar radial Euler flows can drive primary (non-differentiated) flow variables to infinity at the center of motion. Among the variables that blow up at collapse is the pressure, and it is unsurprising that this type of behavior can generate an outgoing shock wave. In this work we prove that there is an alternative scenario in which an incoming, continuous 3-d flow suffers blowup, including in pressure, and yet remains continuous beyond collapse. We verify that this behavior is possible even in cases where the fluid is everywhere moving toward the center of motion at time of collapse. The results underscore the subtlety of shock formation in multi-dimensional flow.