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Author: search.filters.author.Kumankat, NisachonHas files: No

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    Two-Dimensional Fluid Flow Due to Blade-Shaped Waving of Cilia in Human Lungs
    (2025-06-01)
    Kumankat, Nisachon
    ;
    Kamolmitisom, Nachayadar
    The mucociliary clearance system is an innate defense mechanism in the human respiratory tract, which plays a crucial role in protecting the airways from infections. The clearance system secretes mucus from the goblet cells, which scatters in the respiratory epithelium to trap foreign particles entering the airway, and then the mucus is removed from the body via the movement of cilia residing under the mucus and above the epithelium cells. The layer containing cilia is called the periciliary layer (PCL). This layer also contains an incompressible Newtonian fluid called PCL fluid. This study aims to determine the velocity of the PCL fluid driven by the cilia movement instead of a pressure gradient. We consider bundles of cilia, rather than an individual cilium. So, the generalized Brinkman equation in a macroscopic scale is used to predict the fluid velocity in the PCL. We apply a mixed finite element method to the governing equation and calculate the numerical solutions in a two-dimensional domain. The numerical domain is set up to be the shape of a fan blade, which is similar to the motion of the cilia. This problem can be applied to problems of fluid flow propelled via moving solid phases.
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    Well-posedness of generalized Stokes-Brinkman equations modeling moving solid phases
    (2023-01-01)
    Kumankat, Nisachon
    ;
    Wuttanachamsri, Kanognudge
    Fluid flow through a free-fluid region and the adjacent porous medium has been studied in various problems, such as water flow in rice fields. For the problem with self-propelled solid phases, we provide a generalized Stokes equation for the free-fluid domain and the Brinkman equation in a macroscopic scale due to the movement of self-propelled solid phases rather than a single solid in the porous medium. The model is derived with the assumption that the porosity is not a constant. The porosity in the mathematical model varies depending on the propagation of the solid phases. These two models can be matched at the free-fluid/porous-medium interface and are developed for real world problems. We show the proof of the well-posedness of the discretized form of the weak formulation obtained from applying a mixed finite element scheme to the generalized Stokes-Brinkman equations. The proofs of the continuity and coercive property of the linear and bilinear functionals in the discretized equation are illustrated. We present the existence and uniqueness of the generalized Stokes-Brinkman equations for the numerical problem in two dimensions. The system of equations can be applied to fluid flow propelled by moving solid phases, such as mucus flow in the trachea.
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    Finsler Metrics Induced by a Similarity Function
    (2020-01-01)
    Kumankat, Nisachon
    ;
    Pantaragphong, Praiboon
    ;
    Sabau, Sorin V.
    In the present paper, the geometrical properties of a topological space endowed with a similarity was studied. Its relation with weighted quasi-metrics and Finsler metrics of Randers type was discussed. Finally, some applications to bioinformatics and computer science by relating similarities to dynamic programming algorithms are considered. In conclusion, the space containing the real-world data is non-symmetric and non-linear.