Numerical 3D constraints on convective eddy time-correlations: Consequences for stochastic excitation of solar p modes

A 3D simulation of the upper part of the solar convective zone is used to obtain information on the frequency component, (chi)k, of the correlation product of the turbulent velocity field. This component plays an important role in the stochastic excitation of acoustic oscillations. A time analysis of the solar simulation shows that a Gaussian function does not correctly reproduce the (nu)-dependency of (chi)k inferred from the 3D simuation in the frequency range where the acoustic energy injected into the solar p modes is important ((nu)( asymptotically equal)2-4 mHz). The (nu)-dependency of (chi)k is fitted with different analytical functions which can then conveniently be used to compute the acoustic energy supply rate P injected into the solar radial oscillations. With constraints from a 3D simulation, adjustment of free parameters to solar data is no longer necessary and is not performed here. The result is compared with solar seismic data. Computed values of P obtained with the analytical function which fits best (chi)k are found ~2.7 times larger than those obtained with the Gaussian model and reproduce better the solar seismic observations. This non-Gaussian description also leads to a Reynolds stress contribution of the same order as the one arising from the advection of the turbulent fluctuations of entropy by the turbulent motions. Some discrepancy between observed and computed P values still exist at high frequency and possible causes for this discrepancy are discussed.