MSA Journals

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Browsing MSA Journals by Author "A. Ammar, Samah"

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    Equations of Motion for Charged Spinning Fluid in Bi-metric Type Theories of Gravity
    (October university for modern sciences and Arts MSA, 2023) E. Kahil, Magd; A. Ammar, Samah; A. Refaey, Shymaa
    The General theory of relativity is one of the most successful theories of gravity. Despite its successful applications, it has some difficulties in examining the behaviour of particles precisely in strong gravitational fields. Bi-metric type theories of gravity are classified as alternative theories of gravity that describing such strong gravitational fields, such as the gravitational field formed at the core of our galaxy. In order to obtain the equations of motion for spinning fluids, we use the Weyssenhoff tensor to express the spin fluid. The equations of motion for spinning fluids are derived using Euler-Lagrange equation. We present the equations of motion for spinning fluids and their corresponding spin deviation equations in some classes of Bi-metric type theories. Also, we obtain equations of motion for spinning fluids and their corresponding spin deviation for a variable mass. Moreover, we extend our study to examine the status of motion for spinning charged fluids and their corresponding spin deviation equations.
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    Equations of Motion for Spinning Fluids and their Deviation Equations in Finslerian Geometry
    (October university for modern sciences and Arts MSA, 2023) E. Kahil, Magd; A. Ammar, Samah; A. Refaey, Shymaa
    Finsler geometry is a natural extension of the Riemannian geometry and a good a platform used to interpret the infrastructure of physical phenomena, especially for relativistic applications. Accordingly it is worthy to study spinning fluids in the context of this geometry that would share their benefits in cosmological applications. Equations of motion of spinning fluids and their corresponding deviation equations are obtained. The problem of motion for studying a fluid with a variable mass is also obtained. The set of Equations of spinning fluids and spinning deviation fluids equations for some classes of the Finslerian geometry have been derived, using a modified type of the Bazanski Lagrangian. Due to the richness of the Finslerian geometry, a new perspective for revisiting the problem of stability is based on solving the deviation equations of spinning fluids in strong fields of gravity is performed. Such a problem has a direct application on examining the stability of accretion disk orbiting Sgr A*.