scholarly journals Numerical study on the impulsive growth of a gaseous plug inside a cylindrical vein with compliant coating

Bioimpacts ◽  
2017 ◽  
Vol 8 (4) ◽  
pp. 271-279
Author(s):  
Mohammad T. Shervani-Tabar ◽  
Babak Farzaneh ◽  
Reza Ahrabi ◽  
Seyed E. Razavi
Keyword(s):  
Numerical Study ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Numerical Results ◽  
Compliant Coating ◽  
Internal Wall ◽  
Maximum Volume ◽  
Bubble Generation ◽  
Rigid Cylinder ◽  
The Impact

Introduction: Employing of gaseous plugs inside a vein for preventing of blood flow to the damaged or cancerous tissues has been known as a gas embolism in the medicine. In this research, a numerical investigation has been carried out on the delivery of the liquid drug DDFP, encapsulated in the microlipid-coated spheres (MLCSs), to target the human vein for construction of the gaseous plug inside the veins. Methods: The encapsulated liquid drug DDFP were delivered to the vein by injection of an emulsion. Releasing of the liquid drug DDFP results in an explosive growth of a gaseous plug inside the vein. The targeted vein was served as a rigid cylinder with a compliant coating. The boundary integral equation method has been employed for the numerical simulation of the hydrodynamic behavior of the gaseous plug inside the vein. Results: Numerical results showed that in the case of a rigid cylinder vein with an internal compliant coating, the maximum volume of the gaseous plug was smaller than the case of just a rigid cylinder vein. Furthermore, its elapsed time from the instant of bubble generation to the instant when the bubble reaches its maximum volume was shorter. Numerical results also showed that the compliant coating on the internal wall of the rigid cylindrical vein had a tendency of reducing the impact of the explosive growth of the gaseous plug. Conclusion: This numerical research showed that the compliant coating on the internal wall of the rigid cylindrical vein had the tendency of reducing the impact of the impulsive growth of the gaseous plug. Therefore, in the case of having severed arteriosclerosis, treatment of the cancerous or damaged tissues by use of the gaseous embolism must be done very carefully in order to prevent the hazardous effects of the gaseous plug’s impulsive growth.

Numerical Study on the Growth and Collapse of a Cavitation Bubble inside a Rigid Cylinder with a Compliant Coating

2014 ◽  
Vol 875-877 ◽  
pp. 1194-1198
Author(s):  
Fardin Rouzbahani ◽  
M.T. Shervani-Tabar
Keyword(s):  
Integral Equation ◽  
Boundary Integral Equation ◽  
Cavitation Bubble ◽  
Numerical Study ◽  
Finite Difference Methods ◽  
Life Time ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Compliant Coating ◽  
Rigid Cylinder

In this paper, growth and collapse of a cavitation bubble inside a rigid cylinder with a compliant coating (a model of humans vessels) is studied using Boundary Integral Equation and Finite Difference Methods. The fluid flow is treated as a potential flow and Boundary Integral Equation Method is used to solve Laplaces equation for velocity potential. The compliant coating is modeled as a membrane with a spring foundation. The effects of the parameters describing the flow and the parameters describing the compliant coating on the interaction between the fluid and the cylindrical compliant coating are shown throughout the numerical results. It is shown that by increasing the compliancy of the coating, the bubble life time is decreased and the mass per unit area has an important role in bubble behavior.

Analytical and Numerical Study of Nearshore Multiple Oscillating Water Columns

2013 ◽  
Author(s):  
Kourosh Rezanejad ◽  
Joydip Bhattacharjee ◽  
C. Guedes Soares
Keyword(s):  
Water Depth ◽  
Numerical Study ◽  
Integral Equation Method ◽  
Wave Theory ◽  
Boundary Integral ◽  
Water Columns ◽  
Finite Water Depth ◽  
Cartesian Coordinate ◽  
Oscillating Water Columns ◽  
Good Agreement

In the present study, the performance of two chamber nearshore oscillating water columns (OWCs) in finite water depth is analyzed based on the linearized water wave theory in the two dimensional Cartesian coordinate systems. The barriers are assumed to be fixed and the turbine characteristics are assumed linear with respect to the fluctuations of volume flux and pressure inside the chamber. The free surface inside the chambers is modeled as a non-plane wave surface. Two different mathematical models are employed to solve the hydrodynamic problem; the semi-analytic method of matched eigenfunction expansion and the numerical scheme of Boundary Integral Equation Method (BIEM). The numerical results are compared with the semi-analytic results and show good agreement. The effects of the distance between the barriers and the length of the barriers on the efficiency of the OWC device are investigated. The results of two chambers OWC are also compared with the results for an equivalent single OWC chamber. Further, the effect of the water depth on the capacity of the wave power absorption is discussed.

Simulation of plunging wave impact on a vertical wall

1996 ◽  
Vol 327 ◽  
pp. 221-254 ◽  
Author(s):  
Sheguang Zhang ◽  
Dick K. P. Yue ◽  
Katsuji Tanizawa
Keyword(s):  
Scaling Laws ◽  
Numerical Study ◽  
Vertical Wall ◽  
Quantitative Agreement ◽  
Oblique Impact ◽  
Boundary Integral ◽  
Wave Impact ◽  
Initial Stage ◽  
Integral Scheme ◽  
The Impact

We present a numerical study of the impact of a two-dimensional plunging wave on a rigid vertical wall in the context of potential flow. The plunging wave impinging the wall is generated using a mixed-Eulerian-Lagrangian (MEL) boundary-integral scheme. The initial stage of the impact is characterized by an oblique impact of a liquid wedge on the wall and is solved using a similarity solution. Following the initial impact, the MEL simulation is continued to capture the transient impact process. The effect of an air cushion trapped between the plunger and the wall is considered. In addition to details such as temporal evolutions and surface profiles, the main interests are the maximum impact pressure on the wall and its rise time. To arrive at appropriate scaling laws for these, simulations are performed and correlations are explored for a broad range of local plunging wave kinematic and geometric parameters. To assess the present results, direct comparisons are made with the experiment of Chan & Melville (1988). Reasonable quantitative agreement is obtained and likely sources for discrepancies are identified and discussed.

A Numerical Study of Wave Energy Converter in the Form of an Oscillating Water Column Based on a Mixed Eulerian-Lagrangian Formulation

2010 ◽  
Author(s):  
Chunrong Liu ◽  
Zhenhua Huang ◽  
Adrian Law Wing Keung ◽  
Nan Geng
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Numerical Study ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Lagrangian Formulation ◽  
Oscillating Water Column ◽  
Extraction Chamber ◽  
Air Chamber ◽  
Air Turbine

A desingularized boundary integral equation method (DBIEM) is employed to study the wave energy extraction by an oscillating water column (OWC) device. The method is based on a mixed-Eulerian-Lagrangian formulation. We examine the effects of the relative draught on the efficiency of 2D OWC energy converters. The oscillating air pressure inside the OWC chamber is modeled by assuming that the air is incompressible and the air-turbine mass-flow rate is proportional to the pressure difference (a linear turbine). For shallow draughts the numerical results agree well with available analytical results. The wave-excited seiching inside the extraction chamber is discussed and the variation of extraction efficiency with dimensionless air-chamber width for different immersion depths is reported.

A Submerged Compliant Breakwater

1992 ◽  
Vol 114 (2) ◽  
pp. 83-90 ◽  
Author(s):  
A. N. Williams ◽  
P. T. Geiger ◽  
W. G. McDougal
Keyword(s):  
Flexural Rigidity ◽  
Numerical Technique ◽  
Structural Parameters ◽  
Unit Length ◽  
Fluid Velocity ◽  
Fluid Motion ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Numerical Results ◽  
Small Scale

A numerical technique is utilized to investigate the dynamics of a submerged compliant breakwater consisting of a flexible, beamlike structure anchored to the seabed and kept under tension by a small buoyancy chamber at the tip. The fluid motion is idealized as linearized, two-dimensional potential flow and the equation of motion of the breakwater is taken to be that of a one-dimensional beam of uniform flexural rigidity and mass per unit length subjected to a constant axial force. The boundary integral equation method is applied to the fluid domain, modifications are made to the basic formulation to account for the zero thickness of the idealized structure and the singularity in the fluid velocity which occurs at the breakwater tip. The dynamic behavior of the breakwater is described through an appropriate Green function. Numerical results are presented which illustrate the global influence of the tip singularity on the solution and the effects of the various wave and structural parameters on the efficiency of the breakwater as a barrier to wave action. Small-scale physical model tests were also carried out to validate the foregoing theory. In general, the agreement between experimental and numerical results was reasonable, but with considerable scatter.

Numerical Modeling of Buoyancy Induced Convection in Finned Heat Sinks in Presence of Unheated and Heated Shrouds

2005 ◽  
Author(s):  
S. S. Bahga ◽  
A. Bhattacharya ◽  
Roop L. Mahajan
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Heat Sink ◽  
Numerical Study ◽  
Numerical Results ◽  
Heat Sinks ◽  
Maximum Heat ◽  
Maximum Heat Transfer ◽  
Wide Range ◽  
The Impact

This paper investigates the effects of the presence of unheated and heated shrouds on the thermal performance of longitudinal finned heat sinks. A comprehensive numerical study was conducted to determine the impact of the shroud clearance from the tip of the fins and shroud heating. The first part of the study deals with the effects of an unheated shroud on finned heat sinks of different fin height, fin pitch and length in an attempt to cover a wide range of geometry. The numerical results reveal an optimum clearance for maximum heat transfer. For all heat sinks studied the unheated shroud improved the performance by as much as 15% until the shroud was very close when the performance decreased by as much as 10%. In the second part of the paper, the effects of heating of the shroud were considered. In these numerical runs, an isothermal boundary condition was imposed on the shroud. For the heating levels considered, it was found that heating of the shrouds can increase or lower the thermal performance of the heat sink depending on the heat sink geometry and shroud clearance. Finally, the numerical results also revealed a systematic dependence of the normalized Nusselt number on the Rayleigh number for a given heat sink geometry.

scholarly journals Field Modeling the Impact of Cracks on the Electroconductivity of Thin-Film Textronic Structures

Electronics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 402 ◽  
Author(s):  
Stanisław Pawłowski ◽  
Jolanta Plewako ◽  
Ewa Korzeniewska
Keyword(s):  
Electrical Resistance ◽  
Numerical Models ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Structural Defects ◽  
Flexible Substrates ◽  
Wearable Electronics ◽  
Metallic Films ◽  
Field Modeling ◽  
The Impact

Wearable electronics are produced by depositing thin electroconductive layers with low resistance on flexible substrates. In the process of producing such metallic films, as well as during their usage, structural defects may appear which affect their electrical properties. In this paper, we present analytical and numerical models for understanding phenomena related to the electrical conductivity of thin electroconductive layers. The algorithm in the numerical model is based on the boundary integral equation method. The formulas enable calculation of the potential distribution and electric field strength of the analyzed structures, and describe the impact of cracks on their electrical resistance. The validity of the proposed models was verified by experimental results.

Analytical and Numerical Study of Nearshore Multiple Oscillating Water Columns

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Kourosh Rezanejad ◽  
Joydip Bhattacharjee ◽  
Carlos Guedes Soares
Keyword(s):  
Water Depth ◽  
Numerical Study ◽  
Integral Equation Method ◽  
Wave Theory ◽  
Boundary Integral ◽  
Water Columns ◽  
Finite Water Depth ◽  
Cartesian Coordinate ◽  
Oscillating Water Columns ◽  
Good Agreement

In the present study, the performance of two chamber nearshore oscillating water columns (OWCs) in finite water depth is analyzed based on the linearized water wave theory in the two-dimensional Cartesian coordinate systems. The barriers are assumed to be fixed and the turbine characteristics are assumed linear with respect to the fluctuations of volume flux and pressure inside the chamber. The free surface inside the chambers is modeled as a nonplane wave surface. Two different mathematical models are employed to solve the hydrodynamic problem: the semi-analytic method of matched eigenfunction expansion and the numerical scheme of boundary integral equation method (BIEM). The numerical results are compared with the semi-analytic results and show good agreement. The effects of the distance between the barriers and the length of the barriers on the efficiency of the OWC device are investigated. The results of two chambers OWC are also compared with the results for an equivalent single OWC chamber. Further, the effect of the water depth on the capacity of the wave power absorption is discussed.

Ricochet of High Speed Aluminium Projectiles From a Steel Plate

2016 ◽  
Author(s):  
Bakhtier Farouk ◽  
Steven B. Segletes
Keyword(s):  
High Speed ◽  
Steel Plate ◽  
Numerical Study ◽  
Incident Angle ◽  
Target Material ◽  
Numerical Results ◽  
Angle Of Incidence ◽  
Velocity Effect ◽  
Impact Angles ◽  
The Impact

A ricochet is a rebound, bounce or skip off a surface, particularly in the case of a projectile (a bullet). Many ricochets are accidental and while the force of the deflection decelerates the projectile, it can still be energetic and almost as lethal as before the deflection. The likelihood of ricochet is dependent on many factors, including projectile shape, projectile material, spin, velocity (and distance), target material and the angle of incidence. A numerical study on aluminum projectiles ricocheting off a steel plate is presented in this paper. The numerical package LS-DYNA is used to model the process of the impact of aluminum projectile on a steel plate. The simulations are carried out for a given range of projectile velocity (250 m/s to 1500 m/s) with varying impact angles. From the numerical results the ricochet angle and the ricochet velocity is predicted in terms of the incident angle and the incident velocity. The impact velocity effect on the ricochet phenomenon is studied. The numerical results are compared with available analytical solutions of the ricochet problem available in the literature.

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