OS1519-461 Effect of Surface Condition of Solid Materials on Wave propagation at Solid-Fluid Interface with Fluid-Structure Interaction

2015 ◽  
Vol 2015 (0) ◽  
pp. _OS1519-46-_OS1519-46
Author(s):  
Tomohisa KOJIMA ◽  
Kazuaki INABA ◽  
Kosuke TAKAHASHI ◽  
Kikuo KISHIMOTO
Keyword(s):  
Wave Propagation ◽  
Surface Condition ◽  
Fluid Structure Interaction ◽  
Fluid Interface ◽  
Solid Materials ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Effect Of Surface

Wave Propagation Across the Interface of Fluid-Structure Interaction With Various Surface Conditions of Solid Medium

2016 ◽  
Author(s):  
Tomohisa Kojima ◽  
Kazuaki Inaba ◽  
Kosuke Takahashi
Keyword(s):  
Contact Angle ◽  
Wave Propagation ◽  
Pressure Wave ◽  
Solid Medium ◽  
Surface Condition ◽  
Fluid Structure Interaction ◽  
Fluid Interface ◽  
Fluid Structure ◽  
Surface Conditions ◽  
Structure Interaction

This study aims to clarify the effect of surface conditions of solid on wave propagation at solid-fluid interface with fluid-structure interaction. Although many studies have been done to develop the theoretical models of fluid-structure interaction caused by wave propagation, they do not take into account the surface conditions of the solid medium on the solid-fluid interface where interaction occurs. In this study, we experimentally investigated the wave propagation across the solid-fluid interface with several value of surface wettabilities and roughnesses of solid. We conducted an impact experiment with a free-falling projectile which hit the cylindrical solid buffer placed on top of the water surface within the elastic tube standing on the ground. During the experiments, cavitation bubbles were generated from the interface of the buffer and water. That generation was inhibited according to the decrease of the value of the contact angle (improve of the wettability) of the buffer surface. The amplitude of transmitted pressure wave from the buffer to water become smaller than the theoretical value according to the decrease of the value of the contact angle on the buffer surface (the smallest value was 55% of the theoretical value). Concerning the surface roughness, the amplitude of transmitted pressure wave becomes smaller than the theoretical value according to the shape of the buffer surface become more different from flat surface (the smallest value was 75% of the theoretical value). These experimental results indicate that by taking into account the surface condition of the solid on the interface, more accurate model of fluid-structure interaction or ways to reduce the damage of structures by fluid-structure interaction would be proposed.

scholarly journals Wave Propagation Across Solid-Fluid Interface With Fluid-Structure Interaction

2015 ◽  
Author(s):  
Tomohisa Kojima ◽  
Kazuaki Inaba ◽  
Kosuke Takahashi
Keyword(s):  
Wave Propagation ◽  
Theoretical Model ◽  
Characteristic Impedance ◽  
Fluid Structure Interaction ◽  
Fluid Interface ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Mechanism Of Wave Propagation ◽  
Free Falling ◽  
The Impact

This paper reports on investigations conducted with a view towards developing a theoretical model for wave propagation across solid-fluid interfaces with fluid-structure interaction. Although many studies have been conducted, the mechanism of wave propagation close to the solid-fluid interface remains unclear. Consequently, our aim is to clarify the mechanism of wave propagation across the solid-fluid interface with fluid-structure interaction and develop a theoretical model to explain this phenomenon. In experiments conducted to develop the theory, a free-falling steel projectile is used to impact the top of a solid buffer placed immediately above the surface of water within a polycarbonate tube. The stress waves created as a result of the impact of the projectile propagated through the buffer and reached the interface of the buffer and water (fluid) in the tube. Two different buffers (polycarbonate and aluminum) were used to examine the interaction effects. The results of the experiments indicated that the amplitude of the interface pressure increased in accordance with the characteristic impedance of the solid medium. This cannot be explained by the classical theory of wave reflection and transmission. Thus, it is clear that on the solid-fluid interface with fluid-structure interaction, classical theories alone cannot precisely predict the generated pressure.

A Study for Theoretical Modeling of Cavitation Inducement From the Solid-Fluid Interface With Fluid-Structure Interaction

2018 ◽  
Author(s):  
Tomohisa Kojima ◽  
Kazuaki Inaba ◽  
Yuto Takada
Keyword(s):  
Wave Propagation ◽  
Fracture Mechanics ◽  
Pressure Wave ◽  
Fluid Structure Interaction ◽  
Initial Crack ◽  
Elastic Tube ◽  
Fluid Interface ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Cavitation Intensity

A theoretical model was explored for predicting cavitation generation from a solid-fluid interface with fluid-structure interaction. Predicting cavitation generation is crucial to evaluate the lifetime of fluid machines. Cavitation has been generated from a solid-fluid interface with tensile stress (pressure) wave propagation across the interface. It was revealed that cavitation generation was suppressed when the surface wettability of the solid in a solid-fluid interface was improved (hydrophilized). It means that a condition exists in which cavitation is not generated despite the existence of bubble nuclei in water. This phenomenon cannot be explained by the conventional theory of fluid mechanics. In this study, an analogy between the theory of crack propagation in fracture mechanics and cavitation generation and propagation from a solid-fluid interface with fluid-structure interactions is developed and applied. An impact experiment was conducted with a free-falling projectile that hit a cylindrical solid buffer placed on top of a water surface within an elastic tube standing on the ground. The projectile impact created a stress wave propagating through the buffer and across the interface of the buffer and water. During the experiments, cavitation bubbles were generated from the interface of the buffer and water due to tensile wave propagation across the interface. Cavitation intensity was controlled by adding a surfactant to water. A bubble was set on the solid-fluid interface beforehand, then its growth with stress (or pressure) wave propagation was observed. The formularization of cavitation occurrence was tested by using initial crack length and stress in fracture mechanics as an analogy for the diameter of pre-set bubble and pressure wave amplitude.

WALL SHEAR STRESSES IN A FLUID–STRUCTURE INTERACTION MODEL OF PULSE WAVE PROPAGATION

2014 ◽  
Vol 14 (02) ◽  
pp. 1450019 ◽  
Author(s):  
FAN HE
Keyword(s):  
Wave Propagation ◽  
Pulse Wave ◽  
Fluid Structure Interaction ◽  
Interaction Model ◽  
Elastic Tube ◽  
Tube Model ◽  
Pulse Wave Propagation ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Internal Radius

In our prior paper, a fluid–structure interaction model of pulse wave propagation, called the elastic tube model, has been developed. The focus of this paper is wall shear stress (WSS) in this model and the effects of different parameters, including rigid walls, wall thickness, and internal radius. The unsteady flow was assumed to be laminar, Newtonian and incompressible, and the vessel wall to be linear-elastic isotropic, and incompressible. A fluid–structure interaction scheme is constructed using a finite element method. The results demonstrate the elastic tube plays an important role in WSS distributions of wave propagation. It is shown that there is a time delay between the WSS waveforms at different locations in the elastic tube model while the time delay cannot be observed clearly in the rigid tube model. Compared with the elastic tube model, the increase of the wall thickness makes disturbed WSS distributions, however WSS values are increased greatly due to the decrease of the internal radius. The results indicate that the effects of different parameters on WSS distributions are significant. The proposed model gives valid results.

scholarly journals Numerical Investigation of Pulse Wave Propagation in Arteries Using Fluid Structure Interaction Capabilities

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Hisham Elkenani ◽  
Essam Al-Bahkali ◽  
Mhamed Souli
Keyword(s):  
Wave Propagation ◽  
Pulse Wave ◽  
Regression Line ◽  
Computing Time ◽  
Fluid Structure Interaction ◽  
Elastic Tube ◽  
Contour Plot ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Constitutive Material Model

The aim of this study is to present a reliable computational scheme to serve in pulse wave velocity (PWV) assessment in large arteries. Clinicians considered it as an indication of human blood vessels’ stiffness. The simulation of PWV was conducted using a 3D elastic tube representing an artery. The constitutive material model specific for vascular applications was applied to the tube material. The fluid was defined with an equation of state representing the blood material. The onset of a velocity pulse was applied at the tube inlet to produce wave propagation. The Coupled Eulerian-Lagrangian (CEL) modeling technique with fluid structure interaction (FSI) was implemented. The scaling of sound speed and its effect on results and computing time is discussed and concluded that a value of 60 m/s was suitable for simulating vascular biomechanical problems. Two methods were used: foot-to-foot measurement of velocity waveforms and slope of the regression line of the wall radial deflection wave peaks throughout a contour plot. Both methods showed coincident results. Results were approximately 6% less than those calculated from the Moens-Korteweg equation. The proposed method was able to describe the increase in the stiffness of the walls of large human arteries via the PWV estimates.

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