scholarly journals Analysis of Risks Associated With Water Pipes in Rapid Flow Waterways Through Waterway Modeling Experiments

2021 ◽  
Vol 35 (5) ◽  
pp. 51-58
Author(s):  
Sin-Woong Choi ◽  
A-Young Choi ◽  
Dong-Hun Han
Keyword(s):  
Flow Velocity ◽  
Maximum Flow ◽  
Water Pipe ◽  
Lower Side ◽  
Water Pipes ◽  
Average Flow Velocity ◽  
Standard Operating ◽  
Rapid Flow ◽  
Water Rescue ◽  
Maximum Flow Velocity

In this study, waterway modeling experiments were conducted by incorporating the information obtained by analyzing accident sites to prevent frequent accidents of firefighters that occur during water rescue operations conducted near water pipes in rapid flow waterways. Based on the conducted experiments, it was observed that the flow velocity increased with decreasing distance from the water pipe. Furthermore, the maximum flow velocity was found to be 3.99 times higher at the posterior end than at the anterior end of the water pipe, and the flow velocity was found to be higher at the lower side than at the upper side of the water pipe’s anterior end. The maximum flow velocity was measured to be 1.65 m/s at a distance of 10 cm from the entrance to the pipe, 2.63 m/s at a distance of 5 cm from the entrance to the pipe, 7.12 m/s within the pipe, and 5.33 m/s at a distance of 5 cm from the pipe’s exit. The average flow velocity was measured to be 0.94 m/s at a distance of 10 cm from the entrance to the pipe, 5.53 m/s within the pipe, and 4.64 m/s at a distance of 5 cm from the pipe’s exit. Furthermore, in this study, relevant standard operating procedures and regulations were taken into consideration. Based on the results obtained from this study, recommendations and guidelines were then accordingly devised for preventing accidents of firefighters that occur during water rescue operations.

scholarly journals The mechanical origin of snow avalanche dynamics and flow regime transitions

2020 ◽  
Author(s):  
Xingyue Li ◽  
Betty Sovilla ◽  
Chenfanfu Jiang ◽  
Johan Gaume
Keyword(s):  
Flow Velocity ◽  
Alpha Angle ◽  
Maximum Flow ◽  
Flow Regimes ◽  
Snow Avalanche ◽  
Snow Avalanches ◽  
Deposition Zone ◽  
Avalanche Dynamics ◽  
Maximum Flow Velocity ◽  
Deposit Height

Abstract. Snow avalanches cause fatalities and economic damages. Key to their mitigation entails the understanding of snow avalanche dynamics. This study investigates the dynamic behaviors of snow avalanches, using the Material Point Method (MPM) and an elastoplastic constitutive law for porous cohesive materials. By virtue of the hybrid Eulerian-Lagrangian nature of MPM, we can handle processes involving large deformations, collisions and fractures. Meanwhile, the elastoplastic model enables us to capture the mixed-mode failure of snow, including tensile, shear and compressive failure. Using the proposed numerical approach, distinct behaviors of snow avalanches, from fluid-like to solid-like, are examined with varied snow mechanical properties. In particular, four flow regimes reported from real observations are identified, namely, cold dense, warm shear, warm plug and sliding slab regimes. Moreover, notable surges and roll-waves are observed peculiarly for flows in transition from cold dense to warm shear regimes. Each of the flow regimes shows unique flow characteristics in terms of the evolution of the avalanche front, the free surface shape, and the vertical velocity profile. We further explore the influence of slope geometry on the behaviors of snow avalanches, including the effect of slope angle and path length on the maximum flow velocity, the $\\alpha$ angle and the deposit height. Unified trends are obtained between the normalized maximum flow velocity and the scaled $\\alpha$ angle as well as the scaled deposit height, reflecting analogous rules with different geometry conditions of the slope. It is found the maximum flow velocity is mainly controlled by the friction between the bed and the flow, the geometry of the slope, and the snow properties. In addition to the flow behavior before reaching the deposition zone, which has long been regarded as the key factor governing the $\\alpha$ angle, we reveal the crucial effect of the stopping behavior in the deposition zone. Furthermore, our MPM model is benchmarked with simulations of real snow avalanches. The evolution of the avalanche front position and velocity from the MPM modeling shows reasonable agreement with the measurement data from literature. The MPM approach serves as a novel and promising tool to offer systematic and quantitative analysis for mitigation of gravitational hazards like snow avalanches.

Comparative study of transcranial color duplex sonography and transcranial Doppler sonography in adults

1993 ◽  
Vol 78 (5) ◽  
pp. 776-784 ◽  
Author(s):  
Martin Schöoning ◽  
Reiner Buchholz ◽  
Jochen Walter
Keyword(s):  
Flow Velocity ◽  
Doppler Sonography ◽  
Transcranial Doppler Sonography ◽  
Maximum Flow ◽  
Duplex Sonography ◽  
Color Duplex Sonography ◽  
Content Type ◽  
Maximum Flow Velocity ◽  
Fine Print ◽  
Flow Velocities

✓ To determine whether the frequency shift recorded in basal cerebral arteries corresponds to “true” flow velocities, a prospective comparative study of transcranial color duplex sonography (TCCD) and transcranial Doppler sonography (TCD) was performed. A 2.0-MHz transducer of a computerized TCCD system and a TCD device were used. The middle cerebral artery (MCA) and anterior cerebral artery (ACA) were examined by TCCD in 49 healthy volunteers (mean age 35 ± 12 years). In 45 of the same volunteers a comparative TCD examination was possible. The studies were carried out blindly by different examiners at separate appointments. Peak systolic flow velocity, end-diastolic maximum flow velocity, time-averaged maximum flow velocity, and the pulsatility index were measured by both techniques. Additionally, for TCCD, time-averaged flow velocity was assessed, the resistance index and a spectral broadening index were calculated, and the energy output required for reliable measurement was analyzed. The TCCD signals were recorded in 98% of both MCA's and ACA's; with TCD, signals were recorded in 98% of MCA's and 87% of ACA's. Although in both vessels the angle-corrected peak systolic and time-averaged maximum velocities were approximately 10% to 15% higher in TCCD than in TCD measurements, correlation of flow velocities between both techniques was significant (p < 0.0001); differences between sides and age-dependency of flow velocities corresponded as well. In a reproducibility study, TCCD was repeated in 27 subjects by a third examiner with significant correlation (p < 0.0001) of both TCCD examinations. It is concluded that the advantage of TCCD is associated more with a qualitative aspect than a quantitative one. The additional visual dimension of TCCD can open new diagnostic possibilities in cerebrovascular disorders.

scholarly journals Two-dimensional computational simulation flow of exhaust gases passing inside an electrostatic precipitator

2016 ◽  
Vol 10 (1) ◽  
pp. 106-112
Author(s):  
Giorgos Kouropoulos
Keyword(s):  
Fluid Mechanics ◽  
Flow Velocity ◽  
Electrostatic Precipitator ◽  
Computational Simulation ◽  
Flow Simulation ◽  
Maximum Flow ◽  
Theoretical Background ◽  
Two Dimensional ◽  
Exhaust Gases ◽  
Maximum Flow Velocity

In the present study the two-dimensional computational simulation flow of hot exhaust gases which are passed inside an electrostatic precipitator will be carried out. Initially, the theoretical background and necessary equations from fluid mechanics will be described. These equations will be used by software for flow simulation. Furthermore, are presented the design of precipitator through which the exhaust gases are passed. In the next step follows the declaration of various parameters of simulation on the software and finally the necessary images of the computational simulation for two case studies will be extracted. The general conclusions that arise are that the maximum flow velocity of exhaust gases prevails only at the beginning of the entrance of the precipitation element. There are different velocities in all other parts of precipitation element. When the exhaust gases approach the collecting electrodes within the element, their velocity is decreased.

Physiological assessment of augmented vascularity induced by VEGF in ischemic rabbit hindlimb

1994 ◽  
Vol 267 (4) ◽  
pp. H1263-H1271 ◽  
Author(s):  
C. Bauters ◽  
T. Asahara ◽  
L. P. Zheng ◽  
S. Takeshita ◽  
S. Bunting ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Iliac Artery ◽  
Internal Iliac Artery ◽  
Guide Wire ◽  
Rabbit Model ◽  
Maximum Flow ◽  
Treated Group ◽  
Saline Control ◽  
Internal Iliac ◽  
Maximum Flow Velocity

This study was designed to assess the physiological consequences of augmented vascularity induced by administration of vascular endothelial growth factor (VEGF), an endothelial cell-specific mitogen, in a rabbit model of hindlimb ischemia. Ten days after excision of the common and superficial femoral arteries from one hindlimb of 24 New Zealand White rabbits, VEGF (n = 15) or saline (control; n = 9) was selectively injected into the ipsilateral internal iliac artery. Limb perfusion was evaluated immediately pre-VEGF (baseline) and again at days 10 and 30. A Doppler guide wire was advanced to the internal iliac artery to record flow velocity at rest and at maximum flow velocity provoked by intra-arterial injection of papaverine. At baseline and at day 10, no differences in flow parameters were observed between the control and the VEGF-treated animals. By day 30, however, flow at rest (P < 0.05), maximum flow velocity (P < 0.001), and maximum blood flow (P < 0.001) were all significantly higher in the VEGF-treated group. These physiological findings complement previous-anatomic studies by providing evidence that a single intra-arterial bolus of VEGF augments flow, particularly maximum flow, in the rabbit ischemic hindlimb. These data thus support the notion that VEGF administration represents a potential treatment strategy for certain patients with lower extremity ischemia.

Transjugular intrahepatic portosystemic shunt: US assessment with maximum flow velocity.

Radiology ◽  
1993 ◽  
Vol 189 (3) ◽  
pp. 789-793 ◽  
Author(s):  
W K Chong ◽  
T A Malisch ◽  
M J Mazer ◽  
C D Lind ◽  
J A Worrell ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Transjugular Intrahepatic Portosystemic Shunt ◽  
Maximum Flow ◽  
Portosystemic Shunt ◽  
Intrahepatic Portosystemic Shunt ◽  
Maximum Flow Velocity

scholarly journals PENGARUH PILAR JEMBATAN PANGO TERHADAP POLA ALIRAN SUNGAI KRUENG ACEH

2018 ◽  
Vol 1 (4) ◽  
pp. 1005-1018
Author(s):  
Teuku Devansyah Putra ◽  
Eldina Fatimah ◽  
Azmeri Azmeri
Keyword(s):  
Flow Velocity ◽  
Flow Pattern ◽  
Cross Section ◽  
Maximum Velocity ◽  
Maximum Flow ◽  
Surface Water Modeling ◽  
River Cross Section ◽  
Maximum Flow Velocity ◽  
Banda Aceh ◽  
River Bend

Abstract: Pango Fly Over is located in the coordinate of 50 32' 07.32" LU (North Latitude) and 950 20' 52.90” BT (East Longitude) on Pango Village, Ulee Kareng Sub District, Banda Aceh. This bridge was built across Krueng Aceh River and the pillars were built in the river so that it narrows the river cross section and affecting the increasing of flow velocity. From the research location observation, it is found that the bridge pillars cause the more narrowing of the river cross section and there is the damage of the riverbank around the river bend located in the downstream of the pillars. If there is no further follow up, it will erode the national road. This research aims to find out flow pattern without and with the pillars, and to know the flow pattern behavior in the river bend. This research uses Surface Water Modeling System (SMS Version 11.2) Program. The length of the river reviewed is ± 500 meters. The flow discharge used in this research is the flood discharge which the period is Q – 100 and the value is 627.74 m³/second (passing the Pango Fly Over). From the result of the flow patter simulations, it is obtained that the maximum flow velocity without the pillars found in the middle location of V3 reviewed point on the distance 45 m from the riverbank is 0.45 m/sec and maximum flow velocity with the pillars found in the middle location of V3 reviewed point on the distance 33 m from the riverbank is 0.35/sec. In the outer bend of the flow pattern simulation result without pillars, it is obtained that the maximum velocity found in V6 reviewd location on the distance 50 m is 0.83 m/sec in the left side of the flow.Meanwhile in the downstream of the bend, the maximum velocity wit the bridge pillars found in V6 reviewd location on the distance 50 m is 0.95 m/det in the left side of the flow. In the bridge pillars downstream location, there is the river bend required the riverbank reinforcement and the riverbed reinforcement in order to avoid the erosion in the riverbank, because it will endanger the public facilities. Abstrak: Jembatan fly over Pango berada pada koordinat  50 32' 07.32" LU dan 950 20' 52.90” BT terletak di desa Pango Kecamatan Ulee Kareng kota Banda Aceh. Jembatan ini di bangun melintang Sungai Krueng Aceh dan pilar jembatan dibangun pada sungai sehingga terjadi penyempitan penampang sungai yang menyebabkan kecepatan aliran bertambah, Dari tinjauan lokasi penelitian pilar jembatan semakin mengalami penyempitan penampang sungai dan terjadi kerusakan tebing di sekitar belokan sungai yang berada di hilir jembatan. Bila tidak segera di tindak lanjuti akan berdampak tergerusnya jalan nasional. Penelitian ini bertujuan untuk mengetahui pola aliran tanpa adanya pilar dengan adanya pilar serta untuk mengetahui perilaku pola aliran yang terjadi pada belokan sungai. Penelitian ini menggunakan program Surfacewater Modeling System (SMS. Versi 11.2). Panjang sungai yang di tinjau ± 500 meter. Debit aliran yang digunakan pada penelitian ini mengunakan debit banjir periode ulang Q-100 tahunan yaitu 627,74 m³/detik (yang melewati jembatan fly over Pango). Dari hasil simulasi pola aliran didapatkan besaran kecepatan aliran tanpa pilar pada lokasi tengah aliran pada titik tinjauan V3 dengan jarak 45 m dari tanggul sungai kecepatan maksimumnya 0,45 m/det dan besaran kecepatan aliran dengan adanya pilar jembatan pada lokasi tengah pilar pada titik tinjauan V3 dengan jarak 33 m dari tanggul sungai kecepatan maksimumnya 0,35 m/det. Pada belokan luar dari hasil simulasi kecepatan aliran tanpa pilar besaran kecepatan maksimum pada titik tinjau V6 dengan jarak 50 m yaitu 0,83 m/det pada kiri aliran. Sedangkan di hilir belokan pada titik tinjau V6 dengan jarak 50 m dengan adanya pilar jembatan besaran kecepatan maksimum yaitu 0,95 m/det kiri aliran. Pada hilir pilar jembatan terdapat belokan sungai yang memerlukan perkuatan tebing dan perkuatan dasar agar tidak terjadi erosi di tebing sungai, sebab hal ini dapat membahayakan terhadap fasilitas umum.

scholarly journals Two-dimensional computational simulation flow of exhaust gases passing inside an electrostatic precipitator

2016 ◽  
Vol 10 (1) ◽  
pp. 106-112
Author(s):  
Giorgos Kouropoulos
Keyword(s):  
Fluid Mechanics ◽  
Flow Velocity ◽  
Electrostatic Precipitator ◽  
Computational Simulation ◽  
Flow Simulation ◽  
Maximum Flow ◽  
Theoretical Background ◽  
Two Dimensional ◽  
Exhaust Gases ◽  
Maximum Flow Velocity

In the present study the two-dimensional computational simulation flow of hot exhaust gases which are passed inside an electrostatic precipitator will be carried out. Initially, the theoretical background and necessary equations from fluid mechanics will be described. These equations will be used by software for flow simulation. Furthermore, are presented the design of precipitator through which the exhaust gases are passed. In the next step follows the declaration of various parameters of simulation on the software and finally the necessary images of the computational simulation for two case studies will be extracted. The general conclusions that arise are that the maximum flow velocity of exhaust gases prevails only at the beginning of the entrance of the precipitation element. There are different velocities in all other parts of precipitation element. When the exhaust gases approach the collecting electrodes within the element, their velocity is decreased.

scholarly journals ANALISA HIDROLIS JARINGAN PIPA DISTRIBUSI UTAMA DAN DISTRIBUSI BAGI PADA SISTEM PENYEDIAAN AIR MINUM (SPAM) IKK WASILE TIMUR

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Robbi Harisman ◽  
Zulkarnain K Misbah ◽  
Edward Risky Ahadian
Keyword(s):  
Water Resources ◽  
Flow Velocity ◽  
Management System ◽  
Water Resource Management ◽  
Maximum Flow ◽  
Maximum Pressure ◽  
Research Activity ◽  
Resource Management System ◽  
Distribution Network Planning ◽  
Maximum Flow Velocity

The existing water resources need to be sustainably managed. Sustainable water resource management system is a managed and managed water resources management system that fully contributes to current and future societal and economic goals while maintaining its ecological sustainability. This research was conducted by direct observation in the field. Then the data obtained from the field in though by using a computer program. This research activity was conducted in East Wasile Sub-district of East Halmahera Regency of North Maluku Province. The results of this study indicate that the diameter of the pipe used is 300 mm diameter, 250 mm, 200 mm, 150 mm, 100 mm, and 63 mm. From the variation of the pipe obtained Maximum pressure 49.37 m or equal to 4.937 bar while minimum pressure of 26.39 m or equal to 2,639 bar. The pressure of the analysis result meets the criteria of distribution network planning that is maximum 9.0 - 12.4 bar and minimum 0.5 - 1.0 bar. Maximum flow velocity of 0.60 m/s and a minimum speed of 0.30 m/s flow velocity on the analysis results meets the planning criteria which according to the provisions of a maximum of 2.5 m/s and a minimum of 0.25 m/s.

Banding of the pulmonary trunk in preparation for a Fontan operation

1999 ◽  
Vol 9 (1) ◽  
pp. 49-54
Author(s):  
Takahiko Sakamoto ◽  
Yorikazu Harada ◽  
Takamasa Takeuchi ◽  
Katsumasa Morishima ◽  
Gengi Satomi ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Fontan Operation ◽  
Maximum Velocity ◽  
Maximum Flow ◽  
Pulmonary Trunk ◽  
Trunk Length ◽  
Pulmonary Flow ◽  
Pulmonary Arterial ◽  
Maximum Flow Velocity ◽  
Aorta Diameter

AbstractBanding of the pulmonary trunk is an important surgical procedure for patients who have con genital cardiac malformations with unrestricted pulmonary flow. We propose a new concept for determining in such circumstances the most appropriate length of the band used to constrict the pulmonary trunk in preparation for a Fontan operation. We studied 14 patients undergoing banding of the pulmonary trunk and measured the following parameters: diameter of aorta, diameter of pulmonary trunk, length of pulmonary arterial band and maximum flow velocity across the banded segment. We calculated an index from our orig inal parameter based on the formula; length of band/(diameter of aorta diameter of pulmonary trunk). The diameter of aorta was 9.5 ± 1.4 mm, and that of the pulmonary trunk was 9.6 ± 2.3 mm. The length of the band was 16.5 ± 3.4 mm, giving a calculated index of 0.188 ± 0.038. The maximum flow velocity was 4.02 ± 0.46 m/s. No correlation was found between the length of the band and body weight, and also no correlation was found between the length of the band and maximum flow velocity. The calculated index had a negative correlation with the maximum velocity of flow across the band (y = -8.13x + 5.56, R = 0.74, p < 0.01). We believe that the proposed index is a useful guide in determining the length of a pulmonary band when preparing patients for a Fontan operation.

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