“…They converted the original system into a dimensionless one and improved the results in to the case of with the aid of some boundary estimates of div u . We would like to mention that both in and (see also ), the initial density ρ 0 is assumed to be a small perturbation of a positive constant and thus bounded away from zero. Finally, it is worth noting that, for the Oldroyd‐type model based on the deformation tensor, Hu and Wang recently obtained a blow‐up criterion for the compressible viscoelastic fluids in terms of the temporal integral of the velocity gradient and then, Du, Liu, and Zhang proved can be replaced by where F is the deformation tensor.…”