Effect of time-varying forcing on spiral waves in excitable media

Name: Kritsana Khaothong

LCSH: Kasetsart University -- Theses. M.S. (Physics) 2019

Classification :.LCCS: QC174.24.S65

LCSH: Kasetsart University. -- Department of Physics -- Theses

LCSH: Spiral waves

LCSH: Nonlinear waves

LCSH: Wave mechanics

Abstract: Spiral waves are often found in excitable media and they are abnormal forms of action potential propagation in the case of hearts. Under an external forcing, the spiral waves drift and are subsequently terminated at the boundary. Spiral waves can be studied in simulations using a discrete reaction-diffusion system, thereby the time step must be less than a numerical stability limit (ts). In this thesis, we present the dynamics of spiral waves in a simulated system under an external forcing as a function of time. Frist, we optimize the time step of the simulation. The optimal time step of 0.4ts and 0.2ts for without forcing and with modified sinusoidal electrical forcing, respectively. Then, we investigate the effect of the period of sinusoidal, square, and triangular functions that are applied to the system. Under the forcing, freely rotating spiral waves drift along a straight line with a velocity almost independent on the forcing period. Therefore, the period of the signals has a little effect on dynamics of free spiral waves. Finally, we study a release of spiral waves pinned to unexcitable circular obstacles by the external forcing. Under a weak forcing, the spiral waves are still pinned to the obstacles. Spiral waves are successfully released from the obstacles when the amplitude of the external forcing stronger than a critical value. In comparison to the case of constant electrical forcing, we can reduce the average field under both sinusoidal and triangular electrical forcing. In contrast, there is no reduction of the average field for the square electric forcing.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Chaiya Luengviriya

Role: Thesis Advisor

Created: 2019

Modified: 2025-07-02

Issued: 2025-07-02

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2562/kritsana-kha-all.pdf

CallNumber: QC174.24.S65 .K75

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Physics

Grantor: Kasetsart University

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