@article{MalekiMohammadi2023, author = {Maleki, Maniya and Mohammadi, Mahdieh}, title = {Velocity and pressure functions of an oscillating flow in a circular Hele-Shaw cell}, series = {Iranian Journal of Physics Research}, volume = {22}, journal = {Iranian Journal of Physics Research}, number = {1}, publisher = {Physics Society of Iran}, doi = {10.47176/ijpr.22.1.81304}, pages = {113 -- 120}, year = {2023}, abstract = {In this study, we have investigated the form of velocity and pressure functions of a fluid oscillating between two parallel glass sheets that form a circular Hele-Shaw cell. The flow has been considered to be radial, incompressible and laminar. The time-dependent Navier-Stokes equation has been solved in cylindrical coordinates using Fourier transform, and the oscillating flow velocity across the thickness of the cell has been obtained at different times. The flow velocity function in the unsteady state is related to the vertical component of the coordinates in the form of parabolic functions and also to the inverse of the radial component. The time dependence appears as a simple harmonic with a frequency equal to the oscillation frequency. The velocity of the flow is maximum at the middle of the cell along its height and gradually decreases from the middle towards the top or bottom plane and reaches zero. Pressure does not depend on the height and changes logarithmically with the radius. The dependence of pressure on time is also a simple harmonic with the external frequency, but it has a phase shift with respect to the velocity.}, language = {en} } @article{HarthTrittelMohammadietal.2025, author = {Harth, Kirsten and Trittel, Torsten and Mohammadi, Mahdieh and Puzyrev, Dmitry and Enezz, Mohammad and Cruz Hidalgo, Raul and Stannarius, Ralf}, title = {Granular gases of rough spheres: Velocity, rotation and collision statistics from in-situ measurements, optical data and simulations}, series = {EPJ Web of Conferences}, volume = {340}, journal = {EPJ Web of Conferences}, editor = {Alam, M. and Das, S.L. and Bose, M. and Murthy, T.G. and Chikkadi, V. and Singh, A. and Luding, S.}, publisher = {EDP Sciences}, doi = {10.1051/epjconf/202534003012}, year = {2025}, abstract = {Granular gases are not only of interest in fundamental physics, but they can also serve as a test ensembles for the validity of collision models employed in (loose) granular matter. The theoretical literature mainly addresses spheres under ideal conditions and simulations allow full access to all particle parameters, but experiments cannot fulfill these idealizations. We investigate granular gases of soft, rough spheres by combining microgravity experiments and adjusted simulations. We introduce Smart Particles with embedded autarkic micro-sensors for in-situ measurements of rotation rates and accelerations. Additionally, we extract 3D positions, translations and orientations of the particles from stereoscopic video data using Machine-Learning based algorithms. We address the partition of kinetic energy between the degrees of freedom, the angular and translational velocity as well as collision statistics. A simulation is adjusted to experiment parameters, showing good agreement of translational motion, but qualitative differences in the decay of rotational kinetic energy.}, language = {en} }