Entropy hemodynamics particle-fluid suspension model through eccentric catheterization for time-variant stenotic arterial wall: Catheter injection

Catheterization has an imperative rule in heat transfer investigations, which are frequently applied to analyze and deal with the heart transfer studies. Here, the entering of a catheter adjusts the flow of the blood and it affects the hemodynamic status in the artery region. In practical clinical cases, catheters cannot be precisely concentric with the artery. The impartial of this work is to investigate the behavior of a blood streaming characteristics, in the case of injecting the catheter eccentrically all the way through a stenotic overlapping artery. In this paper, we consider the heat transfer within the presence of blood corpuscle which has been characterized by a macroscopic two-phase model (i.e. a suspension of erythrocytes in plasma). The model here considers the blood fluid as a liquid fluid with adjourned particles in the gap bounded by the eccentric cylinder. The inside cylinder is identically rigid demonstrating the movable thin catheter and kept at constant temperature, where the outer cylinder is a taper cylinder demonstrating the artery that has overlapping stenosis and it is cooled and maintained at zero temperature. The coupled differential equations for both fluid (plasma) and particle (erythrocyte) phases have been solved. The expressions for the flow characteristics, namely, the flow rate, the impedance (resistance to flow), the wall shear stress and the temperature distribution, have been derived. The model is very useful in medicine, where the hemodynamic speed is higher for eccentric case than that of concentric one. Also, the temperature distribution and the entropy generation in the state of eccentric position are higher than in the case of the concentric position. A significant increase in the magnitude of the impedance and the wall shear stress occurs for an increase in the hematocrit, C for diseased blood.

An Optimum Imaging Scheme for IVUS Arrays: Eccentric Cylinder Wave Compounding

With the development of integrated circuit (IC) technologies, complex transmitting and receiving circuits can be integrated into miniature intravascular ultrasound (IVUS) catheters, making it possible to adopt better synthesizing schemes for better imaging. Eccentric cylinder wave compounding should be an optimum synthesizing scheme for the small size cylinder shaped catheter. Eccentric cylinder waves centered at different points are emitted, signals are collected after each emission, and images can be synthesized with easy post processing. Detailed analyses about resolution and grating lobes were made; the optimum eccentric distance was determined. Simulations were done to examine the resolution, signal-to-noise ratio, and resistance to crosstalk and nonuniformity of arrays. Dual apodization and magnitude-based deconvolution were applied to further improve the results.

Thermal-Flow Characteristics of Ferrofluids in a Rotating Eccentric Cylinder under External Magnetic Force

Heat dissipation has become an important issue due to the miniaturization of various electronic devices. Various methods such as spray and nozzle coolers, heat sinks and so on are used for heat dissipation. However, the emergence of ferrofluids drastically improves the operating characteristics of electromagnetic systems and devices. A ferrofluid is a suspension containing 10-nm magnetic particles in a colloidal solution. This material exhibits paramagnetic behavior and is sensitive to magnetic field and temperature. In this study, heat transfer characteristics of ferrofluids in a rotating eccentric cylinder were investigated using the commercial code, COMSOL Multiphysics. Numerical results of the local Nusselt number, magnetophoretic force and velocity distributions were obtained from various eccentricities of the cylinder, and the results were graphically depicted with various flow conditions.

The Dynamic Analyses of the Eccentric Cylinder Moving on the Inclined Plane

The conservation principle of energy and the mass center movement theorem of rigid body and the moment of momentum theorem relative to the center of mass were used to study the dynamic problems of the eccentric cylinder on the inclined plane. The mass center velocity and the acceleration of the cylinder and the normal pressure and the friction force of the cylinder acting on the inclined plane and etc are given. An example is introduced to show the variations of the physical variants, and the numerical results agree with the theoretical analyses.