scholarly journals Assessment of Different Pressure Drop-Flow Rate Equations in a Pressurized Porous Media Filter for Irrigation Systems

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2179
Author(s):  
Jonathan Graciano-Uribe ◽  
Toni Pujol ◽  
Jaume Puig-Bargués ◽  
Miquel Duran-Ros ◽  
Gerard Arbat ◽  
...  
Keyword(s):  
Porous Media ◽  
Pressure Drop ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Silica Sand ◽  
Rate Equations ◽  
Uncertainty Range ◽  
Head Losses ◽  
Computational Fluid Dynamics Cfd ◽  
Drop Flow

The small open area available at the slots of underdrains in pressurized granular bed filters for drip irrigation implies: (1) the existence of a region with non-uniform flow, and (2) local values of modified particle Reynolds number >500. These flow conditions may disagree with those accepted as valid for common pressure drop-flow rate correlations proposed for packed beds. Here, we carried out detailed computational fluid dynamics (CFD) simulations of a laboratory filter to analyze the results obtained with five different equations of head losses in porous media: (1) Ergun, (2) Darcy-Forchheimer, (3) Darcy, (4) Kozeny-Carman and (5) power function. Simulations were compared with experimental data at different superficial velocities obtained from previous studies. Results for two silica sand media indicated that all equations predicted total filter pressure drop values within the experimental uncertainty range when superficial velocities <38.3 m h−1. At higher flow rates, Ergun equation approximated the best to the observed results for silica sand media, being the expression recommended. A simple analytical model of the pressure drop along flow streamlines that matched CFD simulation results was developed.

Numerical Investigation on Ventilation Strategy for Laboratories: An Approach to Control Thermal Comfort and Air Quality Using Active Chilled Beams

2007 ◽  
Author(s):  
Farhad Memarzadeh ◽  
Jane Jiang ◽  
Andy Manning
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Washington Dc ◽  
Ventilation Strategy ◽  
Flow Rates ◽  
Beam System ◽  
Computational Fluid Dynamics Cfd ◽  
Lower Flow Rate

Laboratories are usually equipment intensive. The supply flow rates required to cool these laboratories are generally higher than in a less equipment intensive zone of the building. The thermal comfort of occupants in laboratories can be controlled by the choice of ventilation strategy. This study employs Computational Fluid Dynamics (CFD) simulation to assess the performance of active chilled beams in a general laboratory layout with some equipment intensive areas and the removal effectiveness of such a system. The chilled beam performance is also compared with at of ceiling diffusers. The results from this study show that the chilled beams improve thermal comfort, and they can be operated at as low as 4 ACH while maintaining very satisfactory average PPD (around 10%) in the occupied zones. The chilled beam system also improves removal effectiveness because of the inherent higher total supply flow rate that results in a better mixing in the room than ceiling diffusers. The chilled beams in the cases studied are seen to have an insignificant effect on the hood containment. As satisfactory thermal comfort and air quality can be achieved at a lower flow rate in comparison with all-air ceiling diffusers, a 14% saving is estimated in annual energy cost for cooling and ventilating a typical lab in the Washington DC area.

Fluid Dynamics of a Partially Collapsible Stenosis in a Flow Model of the Coronary Circulation

1996 ◽  
Vol 118 (4) ◽  
pp. 489-497 ◽  
Author(s):  
Maria Siebes ◽  
Charles S. Campbell ◽  
David Z. D’Argenio
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Coronary Circulation ◽  
Intraluminal Pressure ◽  
Dimensional Changes ◽  
Area Reduction ◽  
Stenosis Severity ◽  
Flexible Wall ◽  
Drop Flow

The influence of passive vasomotion on the pressure drop-flow (ΔP-Q) characteristics of a partially compliant stenosis was studied in an in vitro model of the coronary circulation. Twelve stenosis models of different severities (50 to 90 percent area reduction) and degrees of flexible wall (0 to 1/2 of the wall circumference) were inserted into thin-walled latex tubing and pressure and flow data were collected during simulated cardiac cycles. In general, the pressure drop increased with increasing fraction of flexible wall for a given flow rate and stenosis severity. The magnitude of this effect was directly dependent upon the underlying stenosis severity. The diastolic ΔP-Q relationship of severe, compliant models exhibited features of partial collapse with an increase in pressure drop at a decreasing flow rate. It is concluded that passive vasomotion of a normal wall segment at an eccentric stenosis in response to periodic changes in intraluminal pressure causes dimensional changes in the residual lumen area which can strongly affect the hemodynamic characteristics of the stenosis during the cardiac cycle. This mechanism may have important implications for the onset of plaque fracture and the prediction of the functional significance of a coronary stenosis based on quantitative angiogram analysis.

scholarly journals CFD Simulation of Airflow Dynamics During Cough Based on CT-Scanned Respiratory Airway Geometries

Symmetry ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 595 ◽  
Author(s):  
Guiyue Kou ◽  
Xinghu Li ◽  
Yan Wang ◽  
Mouyou Lin ◽  
Yuping Zeng ◽  
...  
Keyword(s):  
Flow Rate ◽  
Cfd Simulation ◽  
Peak Flow ◽  
Maximum Velocity ◽  
Flow Distribution ◽  
Peak Flow Rate ◽  
Respiratory Airway ◽  
Computational Fluid Dynamics Cfd ◽  
Left And Right ◽  
Cfd Method

The airflow dynamics observed during a cough process in a CT-scanned respiratory airway model were numerically analyzed using the computational fluid dynamics (CFD) method. The model and methodology were validated by a comparison with published experimental results. The influence of the cough peak flow rate on airflow dynamics and flow distribution was studied. The maximum velocity, wall pressure, and wall shear stress increased linearly as the cough peak flow increased. However, the cough peak flow rate had little influence on the flow distribution of the left and right main bronchi during the cough process. This article focuses on the mathematical and numerical modelling for human cough process in bioengineering.

Experimental Study of Down Hole Gas Liquid Separators

2009 ◽  
Author(s):  
Zunce Wang ◽  
Sen Li ◽  
Fengxia Lv ◽  
Yan Xu ◽  
Jinlong Zhang
Keyword(s):  
Flow Rate ◽  
Cfd Simulation ◽  
Structural Parameters ◽  
Cone Angle ◽  
Field Tests ◽  
Operating Parameters ◽  
Separation Performance ◽  
Liquid Ratio ◽  
Gas Well ◽  
Computational Fluid Dynamics Cfd

The technology of Down-hole Gas Liquid Separation and Water Re-injection (DGLSWR) is an economical and effective method to solve gas well fluid accumulation. The separation performance of designed Down-hole Gas Liquid Separator (DGLS) is very important for DGLSWR systems applications. The principle of work and Characteristics of DGLSWR systems are introduced in this paper. Separation performance of DGLS was studied using computational fluid dynamics (CFD) simulation combining laboratory experiment. Relations of main operating parameters, such as flow rate and gas liquid ratio with pressure drop were studied. The effect of flow rate, gas liquid ratio and main structural parameters such as cone angle and exhaust on DGLS separation performance was also studied. Appropriate structure and operating parameters were determined. Field tests indicated satisfactory results as well.

scholarly journals Contributions of Kinetic Energy and Viscous Dissipation to Airway Resistance in Pulmonary Inspiratory and Expiratory Airflows in Successive Symmetric Airway Models With Various Bifurcation Angles

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Sanghun Choi ◽  
Jiwoong Choi ◽  
Ching-Long Lin
Keyword(s):  
Pressure Drop ◽  
Kinetic Energy ◽  
Viscous Dissipation ◽  
Flow Rate ◽  
Airway Resistance ◽  
Energy Balance Equation ◽  
Strongly Correlated ◽  
Bifurcation Angle ◽  
Computational Fluid Dynamics Cfd ◽  
Bifurcation Structures

The aim of this study was to investigate and quantify contributions of kinetic energy and viscous dissipation to airway resistance during inspiration and expiration at various flow rates in airway models of different bifurcation angles. We employed symmetric airway models up to the 20th generation with the following five different bifurcation angles at a tracheal flow rate of 20 L/min: 15 deg, 25 deg, 35 deg, 45 deg, and 55 deg. Thus, a total of ten computational fluid dynamics (CFD) simulations for both inspiration and expiration were conducted. Furthermore, we performed additional four simulations with tracheal flow rate values of 10 and 40 L/min for a bifurcation angle of 35 deg to study the effect of flow rate on inspiration and expiration. Using an energy balance equation, we quantified contributions of the pressure drop associated with kinetic energy and viscous dissipation. Kinetic energy was found to be a key variable that explained the differences in airway resistance on inspiration and expiration. The total pressure drop and airway resistance were larger during expiration than inspiration, whereas wall shear stress and viscous dissipation were larger during inspiration than expiration. The dimensional analysis demonstrated that the coefficients of kinetic energy and viscous dissipation were strongly correlated with generation number. In addition, the viscous dissipation coefficient was significantly correlated with bifurcation angle and tracheal flow rate. We performed multiple linear regressions to determine the coefficients of kinetic energy and viscous dissipation, which could be utilized to better estimate the pressure drop in broader ranges of successive bifurcation structures.

scholarly journals Influence of CFD Analysis on the Design of Cooling Channels for the CCL Cavity for the Spallation Neutron Source

2000 ◽  
Author(s):  
Snezana Konecni ◽  
Nathan K. Bultman
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Test Section ◽  
Cooling System ◽  
Flow Loop ◽  
Pressure Transducers ◽  
Cooling Channels ◽  
Recorded Data ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Flow Meter

Abstract Water flow in cooling channels was simulated using the computational fluid dynamics (CFD) code CFX4. Pressure drop in the cooling channels of the coupled-cavity linac (CCL) cavity was calculated. The effects of the manifold on the pressure drop were studied also. Reducing the pressure drop was a primary goal of this exercise that led to changing the cooling channel entrance regions. Results of this analysis were used in sizing pumps required for the cooling system. For the validation of the simplified numerical model, an experiment was performed to measure the pressure drop in the cooling channels for variable flow rate, using a flow loop. Deionized water was circulated through the test section with a pump and its flow rate was monitored with a turbine flow meter. Pressure was monitored with pressure transducers at five locations including a differential pressure transducer across the test section, and water temperature was taken at the exit of the pump. Pressure drop across the inlet and outlet of the test section was measured and recorded for different flow rates. Flow rate was also monitored and stored simultaneously. From the recorded data, an empirical correlation was derived to describe the pressure drop, dp, as a function of flow rate through the four cooling channels.

Non-Linear Filtration Through Stratified Porous Media: An Experimental Approach to Model the Volumetric Flow Rate and Pressure Drop Relationship

2021 ◽  
Author(s):  
Ashes Banerjee ◽  
Srinivas Pasupuleti ◽  
Vasant Govind Kumar Villuri ◽  
Abhay Kumar Pushkar ◽  
Rajesh Nune ◽  
...  
Keyword(s):  
Porous Media ◽  
Pressure Drop ◽  
Flow Rate ◽  
Experimental Approach ◽  
Volumetric Flow Rate ◽  
Non Linear ◽  
Linear Filtration
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