Tidal dissipation in stars and planets: simulations from first principles

许多太阳系外行星绕其恒星公转的周期只有几个地球日。在如此近的距离，引力潮汐相互作用可以在改变行星轨道和恒星和行星自旋方面发挥重要作用。这些演化过程的时间尺度取决于潮汐流的动能在恒星和行星内部消散的效率，但理论上还没有很好的理解。这个项目是计算性的，将涉及第一原理数值模拟，在高性能计算机上采用最先进的算法，探索恒星和行星流体层中潮汐消散的机制。特别是，我建议调查潮汐流动和湍流对流之间的相互作用，在旋转的恒星，和机制，导致对齐的恒星（和行星）的自旋和行星轨道。这些模拟的结果将用于解释天体物理观测，并预测，例如，行星宿主恒星的旋转速率，以及在其恒星前面过境的最短周期行星的可能轨道衰变。这些预测可以通过未来的观测来检验，例如使用SuperWASP，NGTS，CHEOPS，TESS和PLATO。

Many extrasolar planets orbit their stars in only a few Earth days. At such close distances, gravitational tidal interactions can play an important role in modifying planetary orbits and stellar and planetary spins. The timescales for these evolutionary processes depend on how efficiently the kinetic energy of tidal flows is dissipated inside stars and planets, but this is not well understood theoretically. This project is computational in nature and will involve first principles numerical simulations, employing state-of-the-art algorithms on high-performance computers, to explore the mechanisms of tidal dissipation in the fluid layers of stars and planets. In particular, I propose to investigate the interaction between tidal flows and turbulent convective flows in rotating stars, and the mechanisms that lead to alignment of the stellar (and planetary) spin and the planetary orbit. The results from these simulations will be used to interpret astrophysical observations and to make predictions, for example, of the rotation rates of planet-hosting stars, and of possible orbital decay of the shortest-period planets that transit in front of their stars. These predictions can be tested by future observations using e.g. SuperWASP, NGTS, CHEOPS, TESS and PLATO.