Slow steady-state flow of viscous fluid near vibrating cylinder; analytical solution for asymmetric channel

High frequency oscillations of a circular cylinder in a viscous fluid near a fixed plane are investigated. Solution of an ideal fluid uniform flow, when velocity at the infinity is given, is presented. This solution is supplemented by a circulary flow and the circulatory constant is calculated approximately. Potential fluid flow velocity on the circle surface is displayed in diagrams and in trigonometric serie

Slow steady-state flow of viscous fluid near vibrating cylinder; analytical solution for asymmetric channel

High frequency oscillations of a circular cylinder in a viscous fluid near a fixed plane are investigated. Solution of an ideal fluid uniform flow, when velocity at the infinity is given, is presented. This solution is supplemented by a circulary flow and the circulatory constant is calculated approximately. Potential fluid flow velocity on the circle surface is displayed in diagrams and in trigonometric serie

Low frequency and high intensity ultrasound in vascular surgery: theory, instrumentation and possibilities of clinical application

This paper presents a brief review of applications of ultrasound in modern surgery and results of original studies of the authors in the field of application of low frequency (24-36 kHz) high-intensity (up to 20 W/cm2) ultrasonic vibrations for disruption of thrombi and calcified atherosclerotic plaques in blood vessels. Application of non-rigid wire ultrasonic waveguides with length up to 980 mm and diameter of working tip down to 0.3 mm enables minimally invasive surgical intervention, since a waveguide can be introduced along curved segments of blood vessels through a small incision situated at substantial distance from occlusion. Ultrasonic angioplasty can be successfully applied in combination with administration of thrombolytic drugs. The paper also considers physical mechanisms of thrombus disruption under influence of ultrasonic vibrations, particularly, effects of cavitation and acoustic streaming. We described design of ultrasonic waveguides for endovascular surgery and their manufacturing technology based on plasma-electrolytic etching. Application of finite element method and transfer matrix approach for design and model of wire waveguides is considered. Description of clinical system for ultrasonic angioplasty with automated resonance tuning of a waveguide is also provided. In addition, we report results of clinical application of ultrasonic angioplasty in patients with occlusion of iliofemoral segment

Low frequency and high intensity ultrasound in vascular surgery: theory, instrumentation and possibilities of clinical application

This paper presents a brief review of applications of ultrasound in modern surgery and results of original studies of the authors in the field of application of low frequency (24-36 kHz) high-intensity (up to 20 W/cm2) ultrasonic vibrations for disruption of thrombi and calcified atherosclerotic plaques in blood vessels. Application of non-rigid wire ultrasonic waveguides with length up to 980 mm and diameter of working tip down to 0.3 mm enables minimally invasive surgical intervention, since a waveguide can be introduced along curved segments of blood vessels through a small incision situated at substantial distance from occlusion. Ultrasonic angioplasty can be successfully applied in combination with administration of thrombolytic drugs. The paper also considers physical mechanisms of thrombus disruption under influence of ultrasonic vibrations, particularly, effects of cavitation and acoustic streaming. We described design of ultrasonic waveguides for endovascular surgery and their manufacturing technology based on plasma-electrolytic etching. Application of finite element method and transfer matrix approach for design and model of wire waveguides is considered. Description of clinical system for ultrasonic angioplasty with automated resonance tuning of a waveguide is also provided. In addition, we report results of clinical application of ultrasonic angioplasty in patients with occlusion of iliofemoral segment

Experimental researches of a flexible waveguide of ultrasound vibrations

In this paper we report the results of experimental research of a new flexible and variable-rigidity waveguide, which operation is based on ultrasound vibrations. The tested waveguide is a combination of conical-stepped-cylindrical waveguides, which enables significant improvement of dynamic characteristics with respect to various existing static loads. The resonant frequency for excitation of the waveguide is in the range of 24-26 kHz. The measurements presented in this paper were performed on a STANDA vibration-isolation honeycomb-type table by means of the POLYTEC laser Doppler vibrometer system MSV-400 consisting of a laser interferometer OFV-512, vibrometer controller OFV-5000 and analog-to-digital converter ADC-2424 (PICO,GB) as well as by using HYTEC holographic interferometry system PRIS