Amount of heat transported by time-dependent convection (D_c) divided by the total heat transported by convection plus melt migration (D_T) as a function of asthenosphere thickness a). The corresponding grain size b) was chosen such that the value of tidal dissipation is 10¹⁴ W, or 6 × 10¹³ W for small asthenosphere thicknesses, were a value of 10¹⁴ W was not accessible. Model M1 was used. For the model parameters see Tables 1–4. Nu(Ra) is given according to Eq. (6) for time-dependent convection and according to Eq. (30)for melt migration.