Calculation of the Pressure Gradient, Velocity, and Wall Shear in Arteries for a Given Flow Rate

2011 ◽  
Vol 2 (2) ◽  
Author(s):  
A. S. Abdalla Wassf Isaac
Keyword(s):  
Fourier Series ◽  
Numerical Analysis ◽  
Pressure Gradient ◽  
Mathematical Models ◽  
Flow Rate ◽  
Input Data ◽  
Inverse Method ◽  
Experimental Measurements ◽  
Artery Flow

The aim of this study was to build an inverse method, which best fits a model of artery flow and experimental measurements, and to provide a good quality of input data for the mathematical models so that proper inferences can be drown from the models. Using numerical analysis to convert the flow rate profiles to the pressure gradient profiles, a Fourier series for this profile (∂p/∂z−t) is then obtained. The results obtained were compared with pressure gradient profile in Fourier series.

scholarly journals Experimental and Numerical Analysis on Hydraulic Characteristics of Coastal Aquifers with Seawall

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2343 ◽  
Author(s):  
Woo-Dong Lee ◽  
Young-Jae Yoo ◽  
Yeon-Myeong Jeong ◽  
Dong-Soo Hur
Keyword(s):  
Numerical Analysis ◽  
Pressure Gradient ◽  
Groundwater Flow ◽  
Seawater Intrusion ◽  
Flow Rate ◽  
Groundwater Level ◽  
Coastal Aquifers ◽  
Coastal Aquifer ◽  
Hydraulic Characteristics ◽  
Tank Experiment

In this study, hydraulic model experiments were conducted to measure the saltwater–freshwater equilibrium interface in a coastal aquifer with underground obstructions such as an impermeable seawall. To analyse the hydraulic characteristics inside the coastal aquifer, numerical analysis was conducted using a non-hydrostatic Navier-Stokes solver based on the Porous Body Model (PBM), which can directly analyse groundwater flow. A unique saltwater–freshwater equilibrium interface that does not appear in typical coastal aquifer analyses was observed in a sandy tank experiment. In the experiment, the rise of the groundwater level behind the seawall increased the pressure gradient and groundwater flow rate, causing the saltwater–freshwater interface to move towards the sea and a freshwater region to form on the seabed in front of the seawall. The numerical analysis enabled close examination of the groundwater level distribution, groundwater flow, seawater–freshwater interface, and pore water pressure characteristics of the coastal aquifer with underground obstructions. The sandy tank experiment also provided an understanding of the hydraulic characteristics of groundwater in the coastal aquifer with a seawall, which previously could not be accurately analysed. The experimental and analytical results demonstrated that the rise of groundwater level due to underground obstructions in the coastal aquifer increased the pressure gradient and groundwater flow rate and slowed seawater intrusion. This principle can be employed to sufficiently reduce seawater intrusion of coastal aquifers.

Lymphatic pump function curves in awake sheep

1996 ◽  
Vol 270 (2) ◽  
pp. R486-R488 ◽  
Author(s):  
R. E. Drake ◽  
S. Dhother ◽  
V. M. Oppenlander ◽  
J. C. Gabel
Keyword(s):  
Pressure Gradient ◽  
Mathematical Models ◽  
Flow Rate ◽  
Lymphatic Vessels ◽  
Ringer Solution ◽  
Nonlinear Flow ◽  
Flow Rates ◽  
Passive Flow ◽  
Lymphatic Pumping ◽  
The Relationship

We determined the relationship between flow rate and inflow pressure for intestinal lymphatic vessels in six sheep. First we anesthetized the sheep and cannulated both ends of a 6- to 10-cm-long segment of intestinal lymphatic. We allowed the sheep to recover from the anesthesia for 2-24 h. To determine the flow rate-inflow pressure relationship, we recorded the inflow pressure and infused Ringer solution into the lymphatic at rates from 34 to 510 microliters/min. The flow rate-pressure relationship was not linear and it had two regions. For flow rates less than approximately 150 microliters/min, inflow pressure was greater than outflow pressure. Thus the lymphatic pumped fluid against a pressure gradient. For flow rates > 150 microliters/min, inflow pressure was greater than outflow pressure, and we attributed most of the flow to the favorable inflow-outflow pressure gradient (passive flow). When we used verapamil to inhibit lymphatic pumping, we found no flow for inflow pressure less than outflow pressure, and flow increased linearly for inflow pressure greater than outflow pressure. Our data for actively pumping lymphatic vessels are consistent with the flow vs. pressure relationships derived from mathematical models of the lymphatic pump. Furthermore, our data with verapamil confirm that active lymphatic pumping was responsible for the nonlinear flow vs. pressure relationship for the lymphatic vessels.

Radon removal by aeration: observations on testing, installation and maintenance of domestic treatment units

2009 ◽  
Vol 9 (4) ◽  
pp. 469-475
Author(s):  
T. Turtiainen
Keyword(s):  
Water Quality ◽  
Water Flow ◽  
Removal Efficiency ◽  
Flow Rate ◽  
Test Protocol ◽  
Household Water ◽  
Medium Flow ◽  
Removal Efficiencies ◽  
Frequent Sampling

Radon is one of the contaminants that sometimes impair the water quality of wells, especially those drilled in bedrock. Domestic radon removal units based on aeration have been commercially available for more than ten years. In order to determine how effectively these units remove radon a new test protocol applying frequent sampling while letting 100 litres of water flow, was developed. This way, removal efficiencies can be more accurately calculated and possible malfunctions detected. Seven models of domestic aerators designed for removing radon from household water were tested. The aerators were based on diffused bubble aeration, spray aeration or jet aeration. The average removal efficiencies for 100 litres with a medium flow rate were 86–100% except for a unit that circulated the aerated water back to the well that had removal efficiency of 80% at the maximum. By conducting a questionnaire study usual problems related to the aeration units were localized and recommendations on maintenance and installation are given accordingly.

Accuracy analysis in borders description for municipal entities in the Republic Bashkortostan

2017 ◽  
Vol 924 (6) ◽  
pp. 2-5
Author(s):  
V.N. Puchkov ◽  
R.S. Musalimov ◽  
D.S. Zavarnov
Keyword(s):  
Russian Federation ◽  
Input Data ◽  
Accuracy Analysis ◽  
Rural Settlements ◽  
Regulatory Requirements ◽  
Republic Of Bashkortostan ◽  
Weak Points ◽  
The Republic

In this work the analysis on description of rural settlements boundaries of the Republic of Bashkortostan, based on the experience of other sub-federal units of Russian Federation was made. A range of weak points in collected input data was defined. In total, of 54 municipal districts of the Republic of Bashkortostan (818 rural settlements), 44 districts showed nonconformity of feed data details to regulatory requirements. And the main reason for this is a low quality of input materials such as base maps at scale 1

scholarly journals The influence of temperature and TMGa flow rate on the quality of p-GaN

AIP Advances ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 035109
Author(s):  
Zikun Cao ◽  
Xiaowei Wang ◽  
Degang Zhao ◽  
Feng Liang ◽  
Zongshun Liu
Keyword(s):  
Flow Rate ◽  
Influence Of Temperature

scholarly journals Geometrical Optimization of a Venturi-Type Microbubble Generator Using CFD Simulation and Experimental Measurements

Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 4
Author(s):  
Dillon Alexander Wilson ◽  
Kul Pun ◽  
Poo Balan Ganesan ◽  
Faik Hamad
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Air Flow ◽  
Bubble Diameter ◽  
Diameter Ratio ◽  
Experimental Measurements ◽  
Cfd Model ◽  
Flow Rates ◽  
Throat Diameter

Microbubble generators are of considerable importance to a range of scientific fields from use in aquaculture and engineering to medical applications. This is due to the fact the amount of sea life in the water is proportional to the amount of oxygen in it. In this paper, experimental measurements and computational Fluid Dynamics (CFD) simulation are performed for three water flow rates and three with three different air flow rates. The experimental data presented in the paper are used to validate the CFD model. Then, the CFD model is used to study the effect of diverging angle and throat length/throat diameter ratio on the size of the microbubble produced by the Venturi-type microbubble generator. The experimental results showed that increasing water flow rate and reducing the air flow rate produces smaller microbubbles. The prediction from the CFD results indicated that throat length/throat diameter ratio and diffuser divergent angle have a small effect on bubble diameter distribution and average bubble diameter for the range of the throat water velocities used in this study.

scholarly journals Statistical Approach to Incorporating Experimental Variability into a Mathematical Model of the Voltage-Gated Na+ Channel and Human Atrial Action Potential

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1516
Author(s):  
Daniel Gratz ◽  
Alexander J Winkle ◽  
Seth H Weinberg ◽  
Thomas J Hund
Keyword(s):  
Action Potential ◽  
Mathematical Models ◽  
Cardiac Myocyte ◽  
Population Level ◽  
Na Channel ◽  
Model Parameters ◽  
Healthy Population ◽  
Experimental Measurements ◽  
Voltage Gated ◽  
Experimental Variability

The voltage-gated Na+ channel Nav1.5 is critical for normal cardiac myocyte excitability. Mathematical models have been widely used to study Nav1.5 function and link to a range of cardiac arrhythmias. There is growing appreciation for the importance of incorporating physiological heterogeneity observed even in a healthy population into mathematical models of the cardiac action potential. Here, we apply methods from Bayesian statistics to capture the variability in experimental measurements on human atrial Nav1.5 across experimental protocols and labs. This variability was used to define a physiological distribution for model parameters in a novel model formulation of Nav1.5, which was then incorporated into an existing human atrial action potential model. Model validation was performed by comparing the simulated distribution of action potential upstroke velocity measurements to experimental measurements from several different sources. Going forward, we hope to apply this approach to other major atrial ion channels to create a comprehensive model of the human atrial AP. We anticipate that such a model will be useful for understanding excitability at the population level, including variable drug response and penetrance of variants linked to inherited cardiac arrhythmia syndromes.

Investigation of suction flow characteristic in the inertance hydraulic converters for efficiency improvement

2021 ◽  
pp. 095965182110248
Author(s):  
Xiaoming Chen ◽  
Yuchuan Zhu ◽  
Travis Wiens ◽  
Doug Bitner ◽  
Minghao Tai ◽  
...  
Keyword(s):  
Flow Rate ◽  
Flow Characteristic ◽  
Performance Indicator ◽  
Flow Characteristics ◽  
Check Valve ◽  
Analytical Models ◽  
Switching Frequency ◽  
Experimental Measurements ◽  
Efficiency Improvement ◽  
Suction Flow

The inertance hydraulic converter relies on fluid inertance to modulate flow or pressure and is considered to be a competitive alternative to the conventional proportional hydraulic system due to its potential advantage in efficiency. As the quantification of fluid inertance, the suction flow characteristic is the crucial performance indicator for efficiency improvement. To explore the discrepancy between the passive inertance hydraulic converter featured by the check valve and the active inertance hydraulic converter driven by an equivalent 2/3 way fast switching valve in regard to suction flow characteristics, analytical models of the inertance hydraulic converters were established in MATLAB/Simulink. The validated models of the respective suction components were incorporated in the overall analytical models and their suction flow characteristics were theoretically and experimentally discussed. The analytical predictions and experimental measurements for the current configurations indicated that the active inertance hydraulic converter yields a larger transient suction flow rate than that of the passive inertance hydraulic converter due to the difference of the respective suction components. The suction flow characteristic can be modulated using the supply pressure and duty cycle, which was confirmed by experimental measurements. In addition, the suction flow characteristics are heavily affected by the resistance of the suction flow passage and switching frequency. There is a compromise between the resistance and switching frequency for inertance hydraulic converters to achieve large suction flow rate.

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