OPTIMAL TIME DECAY RATES FOR THE COMPRESSIBLE NAVIER-STOKES SYSTEM WITH AND WITHOUT YUKAWA-TYPE POTENTIAL

We consider the time decay rates of smooth solutions to the Cauchy problem for the compressible Navier-Stokes system with and without a Yukawa-type potential. We prove the existence and uniqueness of global solutions by the standard energy method under small initial data assumptions. Furthermore, if the initial data belong to L-1 (R-3), we establish the optimal time decay rates of the solution as well as its higher-order spatial derivatives. In particular, we obtain the optimal decay rates of the highest-order spatial derivatives of the velocity. Finally, we derive the lower bound time decay rates for the solution and its spacial derivatives.