Stability analysis of blood flow in multilayered viscoelastic tubes

Blood flow in arteries and veins as collapsible tubes is determined by fluid–structure interaction. Multilayered structure of the vessel wall and mechanical properties of its layers may influence the flow stability, flow rate and wall oscillations. Material parameters of the layers are estimated in experiments

Suppression of Absolute Instabilities by Appropriate Choice of Rheological Parameters of Anisotropic Viscoelastic Tube Conveying Fluid

The stability of the steady flow of a viscous liquid through a thick-wall, three-layer, viscoelastic tube with different rheological parameters for each layer is studied. It is shown that the system can be in both absolute and convective unstable states. It is shown that the absolute instability of the system can be converted into a convective instability, and in some cases the system can even be stabilized with an appropriate choice of the rheological parameters. It is found that an anisotropic tube composed of layers possessing distinct rheological values can completely eliminate all absolute instability modes. The present model can be applied to blood vessels that are composed of three viscoelastic layers with distinct rheological properties and to distensible tubes conveying fluids in different technical devices

Elastic wing response’s to an incoming gust

The behavior of thin elastic blade and wing subjected to a travelingdisturbance is considered. The blade response to an incoming gust ispredicted, then the pressure around the blade is coupled to the far fieldpressure in order to predict the intensity of acoustic radiation as well as theacoustic wave propagation in far field. The effect of the elasticity of theblade on the acoustic wave is predicted. The blade vibration induced bylanding acoustic wave is investigated. The two dimensions inviscid flowaerodynamic theorem associated with the strip theorem are used to modelthe flow around the elastic thin wing. Bernoulli-Euler theorem are used inorder to describe the wing motion. The fluid and the wing motions arecoupled via the boundaries condition at the blade surface. The incominggust considered here is a monochromatic wave traveling with a givenspeed. The problem formulation leads to a forced well known aeroelasticityFung equation. The eigenvalue of the homogeneous part are computedand a formal solution of the forced equation is obtained.The behavior of thin elastic blade and wing subjected to a travelingdisturbance is considered. The blade response to an incoming gust ispredicted, then the pressure around the blade is coupled to the far fieldpressure in order to predict the intensity of acoustic radiation as well as theacoustic wave propagation in far field. The effect of the elasticity of theblade on the acoustic wave is predicted. The blade vibration induced bylanding acoustic wave is investigated. The two dimensions inviscid flowaerodynamic theorem associated with the strip theorem are used to modelthe flow around the elastic thin wing. Bernoulli-Euler theorem are used inorder to describe the wing motion. The fluid and the wing motions arecoupled via the boundaries condition at the blade surface. The incominggust considered here is a monochromatic wave traveling with a givenspeed. The problem formulation leads to a forced well known aeroelasticityFung equation. The eigenvalue of the homogeneous part are computedand a formal solution of the forced equation is obtaine

Stability analysis of blood flow in multilayered viscoelastic tubes

Blood flow in arteries and veins as collapsible tubes is determined by fluid–structure interaction. Multilayered structure of the vessel wall and mechanical properties of its layers may influence the flow stability, flow rate and wall oscillations. Material parameters of the layers are estimated in experiments

Stabilization of the turbulent flows in anisotropic viscoelastic tubes

Abstract Flow around the aircrafts and marine vehicles is turbulized that increases the skin-friction drag and fuel consumption. Here stability of the fully developed turbulent flow of an incompressible fluid in the viscoelastic tube is considered. The eddy viscosity concept is considered to be adequate and the flow velocity, wall displacement and pressures in the fluid and solid wall are timeaveraged quantities. Continuity conditions for the components of the velocity and stress tensor at the fluid-wall interface and no displacement condition at the outer wall of the tube are considered. Solution of the coupled system has been found in the form of the normal mode and the obtained system has been studied using the numerical technique described in [1,2]. The temporal and spatial eigenvalues and the dependencies of the temporal and spatial amplification rates on the rheological parameters of the wall have been computed. It was shown stability of the modes can be increased by a proper choice of the wall parameters. Successful combinations of the wall thickness, elasticity and viscosity have been found for a large variety of materials. It was shown a substantial reduction in the viscous wall shear stress accompanied by a decrease in the turbulence production or Reynolds stress can be reached via using the viscoelastic coating on the rigid surface. The obtained results are in a good agreement with recent direct numerical computations [3]