Система уравнений сохранения количества движения и энергии, описывающая свободноконвективное течение около вертикальной поверхности в полубесконечной пористой среде при граничных условиях третьего рода, рассмотрена в приближении пограничного слоя. Построены асимптотические разложения по степеням параметра Дарси (Da) . Исследована зависимость характеристик потока от значений параметров Dа и Gr x . Построены аналитические решения, применимые во всей области течения.Ключевые слова: свободная конвекция, пористая среда, пограничный слой, асимптотические разложения, параметр Дарси INFLUENCE OF BOUNDARY CONDITIONS ON FREE CONVECTION FLOW IN POROUS MEDIUM WITH NEWTONIAN HEATING FROM A VERTICAL SURFACE A.A. Bocharova and I.V. Plaksina Far East State Technical University, Vladivostok, RussiaThe system of energy and momentum conservation equations, describing a free convection flow formed near a vertical surface in a semi-infinite porous medium under third-kind boundary conditions, is considered using boundary layer approximations. Asymptotic expansions in powers of a Darcy parameter (Da) are constructed. The dependence of flow characteristics on the governing dimensionless parameters Da and Gr x is analyzed. Analytical solutions available for the entire flow domain are derived.
<p>Surgical treatment of congenital heart defects with the obstruction of the outflow tract of the right ventricle can be performed in several stages. The first stage of surgical correction is the creation of a systemic-pulmonary shunt, followed by radical correction. The main complications of systemic-pulmonary shunts are associated with the development of shunt thrombosis and hypervolemia of the pulmonary circulation. Currently, considering the importance of individual selection of a shunt for effective functioning, the main scientific search is aimed at creating optimal methods that consider all the hemodynamic features of a particular patient. Recently, the direction of mathematical modelling and biomechanical analysis in medicine has been actively developing, facilitating the objective evaluation of the accumulated clinical experience and is one of the main tools in evidence-based medicine. The use of computational fluid dynamics methods for modified Blalock–Taussig shunt analysis allows us evaluate the hemodynamic parameters for various configurations of shunts and anastomosis angles and improve the understanding of pathophysiological processes in the cardiovascular system before or after an application of the modified Blalock–Taussig shunt. Here, we provide an overview of the work related to the use of modelling for the calculation of the currents in the aorta–shunt–pulmonary artery system. It is noteworthy that most studies consider the personalised characteristics of the patients and are therefore highly likely to be used in clinical practice. The main hemodynamic parameters that are analysed with the computer calculations are described. Part of the work is devoted to the stages of computer modelling and the limitations in the implementation of these stages. We believe that this manuscript will be of interest to specialists in cardiovascular surgery and to the several scholars working in areas related to the use of digital technologies in medicine, mathematical modelling in medicine and biomechanics.</p><p>Received 30 January 2020. Revised 25 May 2020. Accepted 9 June 2020.</p><p><strong>Conflict of interest:</strong> Authors declare no conflict of interest.</p><p><strong>Funding:</strong> The work is supported by the program for the development of the Scientific and Educational Mathematical Center of the Volga Federal District (No. 075-02-2020-1478) and a grant for the development of the scientific school of the Perm Region “Computer biomechanics and digital technologies in biomedicine”.</p><p><strong>Author contributions</strong><br />Conception and design: Yu.S. Sinelnikov, V.B. Arutunyan, A.A. Porodikov, A.N. Biyanov, V.S. Tuktamyshev, M.I. Shmurak,<br />A.R. Khairulin<br />Drafting the article: A.A. Porodikov, A.N. Biyanov, A.G. Kuchumov<br />Critical revision of the article: A.N. Biyanov, A.G. Kuchumov<br />Final approval of the version to be published: Yu.S. Sinelnikov, V.B. Arutunyan, A.A. Porodikov, A.N. Biyanov, V.S. Tuktamyshev, M.I. Shmurak, A.R. Khairulin, A.G. Kuchumov</p>
Objective. To study the possibility of using N-terminal pro-BNP fragment as a screening criterion of hemodynamic significant of the functioning arterial duct in extremely premature newborns. Hemodynamically significant functioning arterial duct (HSFAD) is a reason of the development of various complications in extremely premature newborns. The basic method for HSFAD diagnosis is Echo CG. The limited technical abilities of ultrasound devices can prevent from an early diagnosis and timely treatment of this state. The search of additional markers of hemodynamic significance the functioning arterial duct (FAD) is actual. Materials and methods. A continuous prospective observational study included patients aged 1 to 3 days with FAD, gestation period of 2532 weeks and birth weight from 500 to 1500 g. Hemodynamic significance of FAD was determined according to generally accepted Eco CG criteria. The level of NT-pro-BNP was identified with IFA on the third day of life. Mathematical modelling was used to calculate a threshold value of NT-pro-BNP, corresponding to 6500 pg/ml, at which the probability of hemodynamic significance of the functioning arterial duct exceeds 80 %. Results. The assessment of NT-pro BNP concentration on the third day of life permitted to establish the following reliable differences: in the main group, the median concentration for NT-pro BNP was 15000 [IQR 2 587; 26 500] pg/ml, in the comparison group 1920 [IQR 1379; 3467] pg/ml, р = 0.001. Mean force direct correlation, r = 0.52, between Echo CG results and NT-pro-BNP values was stated. Conclusions. The obtained results make it possible to use NT-pro-BNP as a screening criterion of FAD hemodynamic significance in extremely premature newborns.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.