“…Recently, Liu and Xu
17 studied the incompressible limit in a bounded domain for well‐prepared initial data, and Zhang
18 proved the local well‐posedness and incompressible limit of the free‐boundary problem in the compressible elastodynamic equations. Recently, Wang
19 also studied the incompressible limit of nonisentropic Hookean elastodynamics for ill‐prepared initial data in the whole space
. One of the key assumptions in Wang
19 is that the index
is even to obtain the uniform estimates of solutions in
with respect to the Mach number.…”