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Numerical investigations on bubble-induced jetting and shock wave focusing: application on a needle-free injection.

ABSTRACT: The formation of a liquid jet into air induced by the growth of a laser-generated bubble inside a needle-free device is numerically investigated by employing the compressible Navier-Stokes equations. The three co-existing phases (liquid, vapour and air) are assumed to be in thermal equilibrium. A transport equation for the gas mass fraction is solved in order to simulate the non-condensable gas. The homogeneous equilibrium model is used in order to account for the phase change process between liquid and vapour. Thermodynamic closure for all three phases is achieved by a barotropic Equation of State. Two-dimensional axisymmetric simulations are performed for a needle-free device for which experimental data are available and used for the validation of the developed model. The influence of the initial bubble pressure and the meniscus geometry on the jet velocity is examined by two different sets of studies. Based on the latter, a new meniscus design similar to shaped-charge jets is proposed, which offers a more focused and higher velocity jet compared to the conventional shape of the hemispherical gas-liquid interface. Preliminary calculations show that the developed jet can penetrate the skin and thus, such configurations can contribute towards a new needle-free design.

SUBMITTER: Kyriazis N

PROVIDER: S-EPMC6405452 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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Numerical investigations on bubble-induced jetting and shock wave focusing: application on a needle-free injection.

Kyriazis Nikolaos N Koukouvinis Phoevos P Gavaises Manolis M

Proceedings. Mathematical, physical, and engineering sciences 20190220 2222

The formation of a liquid jet into air induced by the growth of a laser-generated bubble inside a needle-free device is numerically investigated by employing the compressible Navier-Stokes equations. The three co-existing phases (liquid, vapour and air) are assumed to be in thermal equilibrium. A transport equation for the gas mass fraction is solved in order to simulate the non-condensable gas. The homogeneous equilibrium model is used in order to account for the phase change process between li ...[more]

PMID: 30853840

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Project description:BACKGROUND:Many studies have demonstrated the effectiveness of extracorporeal shock wave therapy (ESWT) and local corticosteroid injection (LCI) for the treatment of carpal tunnel syndrome (CTS), and some studies showed that the effect of ESWT was superior to LCI. We performed this meta-analysis to compare the clinical effects across the two therapies. METHODS:Relevant randomized controlled trials (RCTs) comparing ESWT and LCI for the treatment of CTS were searched in electronic database. The Cochrane risk bias tool was used for quality assessment. After data extraction and quality assessment of the included studies, a meta-analysis was performed using RevMan 5.3 software. Mean differences (MDs), odds ratios (ORs), and 95% confidence intervals (CIs) were analyzed. The protocol for this systematic review was registered on INPLASY (202080025) and is available in full on the inplasy.com ( https://doi.org/10.37766/inplasy2020.8.0025 ) RESULTS: A total of 5 RCT studies with 204 patients were included from the electronic database. The meta-analysis results showed that two therapies were not significantly different in terms of visual analog scale (VAS) score (P = 0.65), Boston Carpal Tunnel Questionnaire (BQ) score (P = 0.14), sensory distal latency (P = 0.66), and nerve conduction velocity (NCV) of the sensory nerve (P = 0.06). There were significant differences between the results of motor distal latency (P < 0.0001), compound muscle action potential (CMAP) amplitude (P < 0.00001), and sensory nerve action potential (SNAP) amplitude (P = 0.004). CONCLUSIONS:In terms of pain relief and function improvement, the effects of ESWT and LCI are not significantly different. In terms of electrophysiological parameters, LCI has a stronger effect on shortening motor distal latency; ESWT is superior to LCI in improving action potential amplitude. ESWT is a noninvasive treatment with fewer complications and greater patient safety. In light of the heterogeneity and limitations, these conclusions require further research for definitive conclusions to be drawn.

Project description:Conflicting reports in the literature have raised the question whether radial extracorporeal shock wave therapy (rESWT) devices and vibrating massage devices have similar energy signatures and, hence, cause similar bioeffects in treated tissues.We used laser fiber optic probe hydrophone (FOPH) measurements, high-speed imaging and x-ray film analysis to compare fundamental elements of the energy signatures of two rESWT devices (Swiss DolorClast; Electro Medical Systems, Nyon, Switzerland; D-Actor 200; Storz Medical, Tägerwillen, Switzerland) and a vibrating massage device (Vibracare; G5/General Physiotherapy, Inc., Earth City, MO, USA). To assert potential bioeffects of these treatment modalities we investigated the influence of rESWT and vibrating massage devices on locomotion ability of Caenorhabditis elegans (C. elegans) worms.FOPH measurements demonstrated that both rESWT devices generated acoustic waves with comparable pressure and energy flux density. Furthermore, both rESWT devices generated cavitation as evidenced by high-speed imaging and caused mechanical damage on the surface of x-ray film. The vibrating massage device did not show any of these characteristics. Moreover, locomotion ability of C. elegans was statistically significantly impaired after exposure to radial extracorporeal shock waves but was unaffected after exposure of worms to the vibrating massage device.The results of the present study indicate that both energy signature and bioeffects of rESWT devices are fundamentally different from those of vibrating massage devices.Prior ESWT studies have shown that tissues treated with sufficient quantities of acoustic sound waves undergo cavitation build-up, mechanotransduction, and ultimately, a biological alteration that "kick-starts" the healing response. Due to their different treatment indications and contra-indications rESWT devices cannot be equated to vibrating massage devices and should be used with due caution in clinical practice.

Dataset Information

Numerical investigations on bubble-induced jetting and shock wave focusing: application on a needle-free injection.

Publications

Numerical investigations on bubble-induced jetting and shock wave focusing: application on a needle-free injection.

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