arXiv subjects

Marcelo V. Flamarion

Publications and source records attributed to Marcelo V. Flamarion.

27 records · Page 2Linked to original sources

arXiv2022

Soliton interactions with an external forcing: the modified Korteweg-de Vries framework

The aim of this work is to study asymptotically and numerically the interaction of solitons with an external forcing with variable speed using the forced modified Korteweg-de Vries equation (mKdV). We show that the asymptotic predictions agree well with numerical solutions for forcing with constant speed and linear variable speed. Regarding forcing with linear variable speed, we find regimes in which the solitons are trapped at the external forcing and its amplitude increases or decreases in time depending on whether the forcing accelerates or decelerates.

physics.flu-dyn↗

arXiv2022

Solitary wave collisions for Whitham-Boussinesq systems

This work concerns soliton-type numerical solutions for two Whitham-Boussinesq-type models. Solitary waves are computed using an iterative Newton-type and continuation methods with high accuracy. The method allow us to compute solitary waves with large amplitude and speed close to the singular limit. These solitary waves are set as initial data and overtaking collisions are considered for both systems. We show that both system satisfy the geometric Lax-categorization of two-soliton collision. Numerical evidences indicate that one of the systems also admits an algebraic Lax-categorization based on the ratio of the initial solitary wave amplitudes with a different range from the one predicted by Lax. However, we show that such categorization is not possible for the second system.

physics.flu-dyn↗

arXiv2022

Solitary wave interactions with a periodic forcing: the extended Korteweg-de Vries framework

The aim of this work is to study numerically the interaction of large amplitude solitary waves with an external periodic forcing using the forced extended Korteweg-de Vries equation (feKdV). Regarding these interactions, we find that a solitary wave can bounce back and forth remaining close to its initial position when the forcing and the solitary wave are near resonant or it can move away from its initial position without reversing their direction. Additionally, we verify that the numerical results agree well within the asymptotic approximation for broad the forcings.

physics.flu-dyn↗

arXiv2022

Numerical stability of solitary waves in flows with constant vorticity for the Euler equations

The study of the Euler equations in flows with constant vorticity has piqued the curiosity of a considerable number of researchers over the years. Much research has been conducted on this subject under the assumption of steady flow. In this work, we provide a numerical approach that allows us to compute solitary waves in flows with constant vorticity and analyse their stability. Through a conformal mapping technique, we compute solutions of the steady Euler equations, then feed them as initial data for the time-dependent Euler equations. We focus on analysing to what extent the steady solitary waves are stable within the time-dependent framework. Our numerical simulations indicate that although it is possible to compute solitary waves for the steady Euler equations in flows with large values of vorticity, such waves are not numerically stable for vorticities with absolute value much greater than one. Besides, we notice that large waves are unstable even for small values of vorticity.

physics.flu-dyn↗

arXiv2022

Solitary waves on flows with an exponentially sheared current and stagnation points

While several articles have been written on water waves on flows with constant vorticity, little is known about the extent to which a nonconstant vorticity affects the flow structure, such as the appearance of stagnation points. In order to shed light on this topic, we investigate in detail the flow beneath solitary waves propagating on an exponentially decaying sheared current. Our focus is to analyse numerically the emergence of stagnation points. For this purpose, we approximate the velocity field within the fluid bulk through the classical Korteweg-de Vries asymptotic expansion and use the Matlab language to evaluate the resulting streamfunction. Our findings suggest that the flow beneath the waves can have zero, one or two stagnation points in the fluid body. We also study the bifurcation between these flows. Our simulations indicate that the stagnation points emerge from a streamline with a sharp corner.

physics.flu-dyn↗

arXiv2022

The wave stability of solitary waves over a bump for the full Euler equations

In this work, we present a numerical study of the wave stability of steady solitary waves over a localised topographic obstacle through the full Euler equations. There are two branches of the solutions: one from the perturbed uniform flow and the other from the perturbed solitary-wave flow. We find that steady waves from the perturbed uniform flow are always stable with respect to perturbations of its amplitude. Regarding the perturbed solitary-wave, when the perturbed initial condition has smaller amplitude than the steady solution we notice a certain type of stability. Yet, when the perturbed initial condition has larger amplitude than the steady solution an onset of wave-breaking seem to occur.

physics.flu-dyn↗

arXiv2021

Gravity-capillary flows over obstacles for the fifth-order forced Korteweg-de Vries equation

The aim of this work is to investigate gravity-capillary waves resonantly excited by two topographic obstacles in a shallow water channel. By considering the weakly nonlinear regime the forced fifth-order Korteweg-de Vries equation arises as a model for the free surface displacement. The water surface is initially taken at rest and the initial value problem for this equation is computed numerically using a pseudospectral method. We study near-resonant flows with intermediate capillary effects. Details of the wave interactions are analysed for obstacles with different sizes. Our numerical results indicate that the flow is not necessarily governed by the larger obstacle.

physics.flu-dyn↗

arXiv2021

An iterative method to compute conformal mappings and their inverses in the context of water waves over topographies

An iterative numerical method to compute the conformal mapping in the context of propagating water waves over uneven topographies is investigated. The map flattens the fluid domain onto a canonical strip in which computations are performed. The accuracy of the method is tested by using the MATLAB Schwarz-Christoffel toolbox mapping as a benchmark. Besides, we give a numerical alternative to compute the inverse of the conformal map.

physics.flu-dyn↗

arXiv2020

Trapped solitary-wave interaction for Euler equations with low pressure region

Trapped solitary-wave interaction is studied under the full Euler equations in the presence of a variable pressure distribution along the free surace. The physical domain is flattened conformally onto a strip and the computations are performed in the canonical domain. Computer simulations display solitary waves that remain trapped in a low pressure region. In terms of confinement we observe that these waves are stable for small perturbations of either their amplitudes or the pressure forcing term. Furthermore multiple solitary waves are considered within the low pressure region without escaping the low pressure region. We identify regimes in which multiple solitary waves remain trapped after several collisions. In particular we display a regime where three solitary waves are trapped and collide several times, before one escapes at a time. The remaining solitary waves stays trapped in the low pressure region.

physics.flu-dyn↗