Using advanced numerical schemes and grid-refinement we present 2D high-resolution models of solar granulation with particular emphasis to downflowing plumes .
In the high-resolution portion of our simulation , a box measuring 1.97 \times 2.58 \mbox { Mm } ^ { 2 } ( vertical \times horizontal ) , the grid size is 1.82 \times 2.84 \mbox { km } ^ { 2 } .
Calculations at the resolution usually applied in this type of simulations amount to only a few horizontal gridpoints for a downflowing plume .
Due to the increased number of gridpoints in our high resolution domain the simulations show the development of vigorous secondary instabilities of both the plume ’ s head and stem .
Below a depth of about 1 \mbox { Mm } the plume produces patches of low density , temperature , pressure and high vorticity which may last for all of our simulation time , \sim 10 \mbox { minutes } , and probably considerably longer ; they may be ascribed to the 2 \mbox { D } nature of the present calculations .
Centrifugal forces acting in these patches counteract the strong inward pressure .
Probably most importantly , the plume ’ s instabilities give rise to acoustic pulses created predominantly down to \sim 1.5 \mbox { Mm } .
The pulses proceed laterally as well as upwards and are ubiquitous .
Ultimately most of them emerge into the photosphere .
A considerable part of the photospheric ‘ turbulence ’ in these models is due to those pulses rather than to some sort of eddies .
– The upflows in granules are smooth where they reach the photosphere from below even in the present calculations ; however , the pulses may enter in the photosphere also in granular upflows .