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Leo Hari Wiryanto
Department of Mathematics, Institut Teknologi Bandung
Mathematics

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SIMULATION OF ANALYTICAL TRANSIENT WAVE DUE TO DOWNWARD BOTTOM THRUST Tjandra, Sugih Sudharma; Pudjaprasetya, Sri Redjeki; Wiryanto, Leo Hari
Journal of the Indonesian Mathematical Society Volume 21 Number 2 (October 2015)
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.21.2.189.93-104

Abstract

Generation process is an important part of understanding waves, especially tsunami. Large earthquake under the sea is one major cause of tsunamis. The sea surface deforms as a response from the sea bottom motion caused by the earthquake. Analytical description of surface wave generated by bottom motion can be obtained from the linearized dispersive model. For a bottom motion in the form of a downward motion, the result is expressed in terms of improper integral. Here, we focus on analyzing the convergence of this integral, and then the improper integral is approximated into a finite integral so that the integral can be evaluated numerically. Further, we simulate free surface elevation for three different type of bottom motions, classified as impulsive, intermediate, and slow  movements. We demonstrate that the wave propagating to the right, with a depression as the leading wave, followed with subsequent wave crests. This phenomena is often observed in most tsunami events.DOI : http://dx.doi.org/10.22342/jims.21.2.189.93-104
SIMULATION OF ANALYTICAL TRANSIENT WAVE DUE TO DOWNWARD BOTTOM THRUST Sugih Sudharma Tjandra; Sri Redjeki Pudjaprasetya; Leo Hari Wiryanto
Journal of the Indonesian Mathematical Society Volume 21 Number 2 (October 2015)
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.21.2.189.93-104

Abstract

Generation process is an important part of understanding waves, especially tsunami. Large earthquake under the sea is one major cause of tsunamis. The sea surface deforms as a response from the sea bottom motion caused by the earthquake. Analytical description of surface wave generated by bottom motion can be obtained from the linearized dispersive model. For a bottom motion in the form of a downward motion, the result is expressed in terms of improper integral. Here, we focus on analyzing the convergence of this integral, and then the improper integral is approximated into a finite integral so that the integral can be evaluated numerically. Further, we simulate free surface elevation for three different type of bottom motions, classified as impulsive, intermediate, and slow  movements. We demonstrate that the wave propagating to the right, with a depression as the leading wave, followed with subsequent wave crests. This phenomena is often observed in most tsunami events.DOI : http://dx.doi.org/10.22342/jims.21.2.189.93-104
Numerical Simulation of Flood Routing, Model of Dynamic Equations Leo Hari Wiryanto; Ratna Widyawati
Journal of the Indonesian Mathematical Society VOLUME 28 NUMBER 2 (JULY 2022)
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.28.2.1111.122-132

Abstract

Dynamic equations of flow in a rectangular inclined channel are solved numerically for the case where the friction force of the channel wall is neglected by the gravity force. The flow discharge and the cross-section area along the channel are physical quantity that is calculated. In non-dimensional variables, the equations indicate solution in traveling wave occurring for critical flow. Near that type of flow, the perturbation method is applied to get second order equations that are first order partial differential equation with external force from the lower order equations. Numerical solution is obtained by predictor-corrector method, and the effect of these second order equations can be observed to the traveling wave, depending on the type of the flow, su-percritical or subcritical.
An Implicit Finite Difference Method for Thin Film Flow Gusrian Putra; Leo Hari Wiryanto; Ratna Widyawati
Journal of the Indonesian Mathematical Society VOLUME 29 NUMBER 1 (MARCH 2023)
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.29.1.1110.99-105

Abstract

Thin film flow on an inclined plane can be modeled from lubrication theory. Together with boundary conditions, the governing equations can be formulated into a single equation of the thickness of the fluid, and solved numerically by an implicit finite difference method. In analyzing the equation, the linearized equation is considered here, to see the characteristic of the solution as wave propagation and the effect of the physical parameter. We found that the wave propagates by reducing the amplitude, and the wave speed is affected by the steepness of the plane. All of these can be indicated in the linearized equation. Numerical wave-simulation is presented in this paper.
Fourth Order PDE: Model of Thin Film Flow Involving Surface Tension Wiryanto, Leo Hari; Djohan, Warsoma
Journal of the Indonesian Mathematical Society Vol. 31 No. 2 (2025): JUNE
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.v31i2.1454

Abstract

Surface wave on thin film is considered by involving surface tension. The fluid flows on an inclined channel. The model is based on lubrication theory, and presented in a single equation of the thickness of the fluid as wave movement, and the equation is strongly nonlinear. In solving the model, scaling and linearized processes are applied. So that three physical parameters play an important role in the wave propagation: bottom inclination, length of the scaling and the surface tension. Each of those parameters is represented as a term in the equation. Then, the equation is solved numerically by an implicit finite difference method for the linearized equation, so that the solution can be used to observe the effect of those physical quantities. We found that the surface wave propagates with different speed and reducing the amplitude. When the surface tension is involved, the profile of the wave slightly changes, beside it also effect to the movement of the wave. This is simulated in this paper.
Co-Authors Gusrian Putra Ratna Widyawati Sri Redjeki Pudjaprasetya, Sri Redjeki Sugih Sudharma Tjandra, Sugih Sudharma Warsoma Djohan