I will discuss recent works on the wave dynamics of accretion disk around a black hole, focusing on global disk instabilities and (inertial-acoustic) wave modes trapped in the inner disk region. I will explain the role of wave super-reflection and wave absorption at the corotation resonance, as well as how general relativistic effects help to drive these modes overstable. Applications to the quasi-periodic oscillations obsereved in accreting black hole systems (X-ray binaries and AGNs) will also be discussed.