فهرست مطالب سهیل واشقانی فراهانی

The aim is to study nonlinear wave dynamics in solar spicules and jets. The life of jets in the context of Alfven wave dynamics is focused. Here, further insight into the solar atmospheric effects together with initial conditions on the dynamics of Alfven waves along with the characteristic parameters of the spicule or jet itself are provided. Results are based on the theory of magnetohydrodynamics. the location of shock formation by the interplay of the internal and external plasma-beta conditions together with the initial steady flow speeds which are rooted in the initiation location of the solar jet are illustrated. It was known that the plasma-beta of a solar jet affects the shock formation time of torsional Alfven waves. However, its efficiency is shown to be dependent on the external plasma beta conditions. The shock formation time for plasma-beta conditions over unity is directly proportional to the plasma-beta, similar to plasma-beta conditions equal to or below unity. In the case where the plasma-beta inside the magnetic structure is small, the shock formation time is accelerated by increasing the external plasma-beta. In photospheric conditions, as for coronal conditions, the time of shock formation is inversely proportional to the external plasma-beta. When the internal plasma-beta is fixed, for various steady flow speeds, the external plasma-beta accelerates the formation of shocks. These results help us to better understand the role of Alfven waves in solar jets in the transfer of energy to the solar system.

In this study, drying process is modeled in porous media using random walk theory. In this line, first the effect of microscopic quantities derived from random walk theory has been studied on drying rate. Then, the relationship between drying rate and moisture content is obtained taking convection into account. The results obtained in this study indicates the effect of convection on the process of drying in porous media.