Abstract

I describe two calculations relevant to determining the efficiency of tidal dissipation in convective regions of planets and stars. This problem is currently of much interest in connection with extrasolar planetary systems. First, I discuss properties of the linear response of a rotating barotropic fluid to low-frequency forcing by a tidal potential, and I show that a robust frequency-averaged dissipation rate can be obtained through an appropriate impulse calculation. Of particular interest is the dependence of this quantity on the internal structure of the body. Second, I present analytical and numerical results on the frequency-dependent effective viscosity of convection and other fluid flows, addressing the controversial matter of the suppression of the effective viscosity for tidal periods that are short compared to the convective timescales.