2D CFD Modeling of Rapid Water Filling with Air Valves Using OpenFOAM

The rapid filling process in pressurized pipelines has been extensively studied using mathematical models. On the other hand, the application of computational fluid dynamics models has emerged during the last decade, which considers the development of CFD models that simulate the filling of pipes with entrapped air, and without air expulsion. Currently, studies of CFD models representing rapid filling in pipes with entrapped air and with air expulsion are scarce in the literature. In this paper, a two-dimensional model is developed using OpenFOAM software to evaluate the hydraulic performance of the rapid filling process in a hydraulic installation with an air valve, considering different air pocket sizes and pressure impulsion by means of a hydro-pneumatic tank. The two-dimensional CFD model captures the pressure evolution in the air pocket very well with respect to experimental and mathematical model results, and produces improved results with respect to existing mathematical models.

Evolution of Cryptocurrency: Changes in the Use and Consumer Demand for Digital Transactions

The quick advancement of cryptographic forms of money has caused to notice this specific market, with financial backers attempting to comprehend its conduct and analysts attempting to clarify it. The development of digital currencies' costs showed a sort of air pocket and an accident toward the finish of 2017. In view of this occasion, and on the way that Bitcoin is the most perceived digital currency, we propose to assess the infection impact among Bitcoin and other significant cryptographic forms of money. Utilizing the Detrended Cross-Correlation Analysis connection coefficient and looking at the period after and before the accident, we discovered proof of an infection impact, with this specific market being more incorporated now than in the past something that ought to be considered by current and likely financial backers. Cryptocurrency like Bitcoin have developed from being related only with geeks and revolutionaries to being considered by national banks as an innovation to carry out advanced cash. Digital forms of money exist just in computerized shape and can be moved totally between advanced addresses. This is both not normal for traditional electronic cash as perceived by laypersons which goes about as an obligation guarantee on a store with a confided in monetary foundation, for example, a private bank and dissimilar to ordinary bodily cash which might be truly moved by. This implies that any lawful rights related with holding digital forms of money should be diverse in spite of it being staying not entirely clear. In this , we take a gander at the different medicines of cash in the lawful detect and talk about the dangers related with each by drawing on genuine models. We presume that extortion through hacking might actually represent an issue to broad reception of cryptographic forms of money as the shortfall of plan of action against an outsider, for example, a bank amasses hazard in holders of digital currencies. Clients should hence practice alert and comprehend the dangers prior to putting resources into digital currencies. This admonition requires accentuation as many gatherings misunderstand the cryptography inside the innovation as shielding them from such misrepresentation when truth be told it does nothing of the sort. Keywords: Cryptocurrency, Cryptography, Digital Currencies, Bitcoin, Blockchain.

On-Site Medical Management of Avalanche Victims—A Narrative Review

Avalanche accidents are common in mountain regions and approximately 100 fatalities are counted in Europe each year. The average mortality rate is about 25% and survival chances are mainly determined by the degree and duration of avalanche burial, the patency of the airway, the presence of an air pocket, snow characteristics, and the severity of traumatic injuries. The most common cause of death in completely buried avalanche victims is asphyxia followed by trauma. Hypothermia accounts for a minority of deaths; however, hypothermic cardiac arrest has a favorable prognosis and prolonged resuscitation and extracorporeal rewarming are indicated. In this article, we give an overview on the pathophysiology and on-site management of avalanche victims.

Analysis of Sub-Atmospheric Pressures during Emptying of an Irregular Pipeline without an Air Valve Using a 2D CFD Model

Studying sub-atmospheric pressure patterns in emptying pipeline systems is crucial because these processes could cause collapses depending on the installation conditions (the underground pipe covering height, type, fill, and pipeline stiffness class). Pipeline studies have focused more on filling than on emptying processes. This study presents an analysis of the following variables: air pocket pressure, water velocity, and water column length during the emptying of an irregular pipeline without an air valve by two-dimensional computational fluid dynamics (2D CFD) model simulation using the software OpenFOAM. The mathematical model predicts the experimental values of the study variables. Water velocity vectors are also analysed within the experimental facility, assessing the sensitivity of the drain valve to different openings and changes in water column length during the hydraulic phenomenon.

Experimental Characterization of Two-Phase Swirl Flow Interacting With a Circular Bluff Body

This study presents an experimental investigation of two-phase swirl flow interacting with a circular bluff body. A horizontal and transparent multiphase flow loop is employed to investigate the dynamic of swirl flow close to the circular bluff body. Using high-speed photography, air-core development during the transition period is characterized. Analysis of both instantaneous and averaged images provides key information on air-core length and diameter for steady state conditions. The distance from air-core tip to the disk depends on a critical gas-liquid ratio (GLRc). The presence of air pocket behind the circular bluff body depends on a critical distance to the disk.

Assessment of Steady and Unsteady Friction Models in the Draining Processes of Hydraulic Installations

The study of draining processes without admitting air has been conducted using only steady friction formulations in the implementation of governing equations. However, this hydraulic event involves transitions from laminar to turbulent flow, and vice versa, because of the changes in water velocity. In this sense, this research improves the current mathematical model considering unsteady friction models. An experimental facility composed by a 4.36 m long methacrylate pipe was configured, and measurements of air pocket pressure oscillations were recorded. The mathematical model was performed using steady and unsteady friction models. Comparisons between measured and computed air pocket pressure patterns indicated that unsteady friction models slightly improve the results compared to steady friction models.