scholarly journals Numerical vs experimental pressure drops for Boger fluids in sharp-corner contraction flow

2016 ◽  
Vol 28 (10) ◽  
pp. 103104 ◽  
Author(s):  
J. E. López-Aguilar ◽  
H. R. Tamaddon-Jahromi ◽  
M. F. Webster ◽  
K. Walters
Keyword(s):  
Sharp Corner ◽  
Contraction Flow ◽  
Pressure Drops ◽  
Boger Fluids ◽  
Experimental Pressure

scholarly journals Computational Predictions for Boger Fluids and Circular Contraction Flow under Various Aspect Ratios

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 85 ◽  
Author(s):  
J. Esteban López-Aguilar ◽  
Hamid R. Tamaddon-Jahromi
Keyword(s):  
Stress Response ◽  
Normal Stress ◽  
Contraction Flow ◽  
Pressure Drops ◽  
Aspect Ratios ◽  
Model Variant ◽  
Evolution Characteristics ◽  
Contraction Ratio ◽  
Boger Fluids ◽  
Experimental Findings

This work puts forward a modeling study contrasted against experimental, with focus on abrupt circular contraction flow of two highly-elastic constant shear-viscosity Boger fluids, i.e., a polyacrylamide dissolved in corn-syrup PAA/CS (Fluid-1) and a polyisobutylene dissolved in polybutene PIB/PB (Fluid-2), in various contraction-ratio geometries. Moreover, this work goes hand-in-hand with the counterpart matching of experimental pressure-drops observed in such 4:1 and 8:1 aspect-ratio contraction flows, as described experimentally in the literature. In this study, the experimental findings, for Boger fluids with severe strain-hardening features, reveal significant vortex-evolution characteristics, correlated with enhanced pressure-drop phasing and normal-stress response in the corner region. It is shown how such behavior may be replicated through simulation and the rheological dependencies that are necessary to bring this about. Predictive solutions with an advanced hybrid finite-element/volume (fe/fv) algorithm are able to elucidate the rheological properties (extensional viscosity and normal-stress response) that rule such vortex-enhancement evolution. This is accomplished by employing the novel swanINNFM(q) family of fluids, through the swIM model-variant, with its strong and efficient control on elongational properties.

scholarly journals On the use of continuous spectrum and discrete-mode differential models to predict contraction-flow pressure drops for Boger fluids

2017 ◽  
Vol 29 (12) ◽  
pp. 121613 ◽  
Author(s):  
J. E. López-Aguilar ◽  
M. F. Webster ◽  
H. R. Tamaddon-Jahromi ◽  
O. Manero ◽  
D. M. Binding ◽  
...  
Keyword(s):  
Continuous Spectrum ◽  
Contraction Flow ◽  
Pressure Drops ◽  
Discrete Mode ◽  
Boger Fluids ◽  
Flow Pressure

Experimental Adiabatic Two-Phase Pressure Drops of R134a, R236fa and R245fa in Small Horizontal Circular Channels

2011 ◽  
Author(s):  
Chin L. Ong ◽  
John R. Thome
Keyword(s):  
Pressure Drop ◽  
Flow Boiling ◽  
Homogeneous Model ◽  
Prediction Methods ◽  
Two Phase ◽  
Pressure Drops ◽  
Wide Range ◽  
Small Channels ◽  
Experimental Pressure ◽  
Phase Pressure

Experimental adiabatic two-phase pressure drops data for refrigerants R134a, R236fa and R245fa during flow boiling in small channels with internal diameters of 1.03, 2.20 and 3.04 mm are presented. The main purpose was to investigate the effects of channel confinement on adiabatic two-phase pressure drops. Thus, the two-phase pressure drop trends were systematically investigated over a wide range of test conditions for all three refrigerants and channel sizes. Statistical comparisons have also been made by comparing the experimental pressure drop data database with various macroscale and microscale prediction methods from the literature. The comparison showed relatively moderate accuracy for three prediction methods developed for macroscale flows, i.e. Baroczy and Chisholm, Friedel and the homogeneous model with the Cicchitti et al. viscosity relation. As for microscale prediction methods, the Cioncolini et al. annular flow model worked best with 68.5% of the data within ± 30%, followed by the Sun and Mishima and the Zhang et al. methods. Combining this database with the LTCM lab’s earlier database for 0.509 and 0.790 mm channels, there appears to be no evidence of a macro-to-microscale transition, at least with respect to two-phase pressure drops.

ACTIVITY OF TWO SPECIES OF CALLIPHORA (DIPTERA) DURING BAROMETRIC PRESSURE CHANGES OF NATURAL MAGNITUDE

1961 ◽  
Vol 39 (5) ◽  
pp. 623-635 ◽  
Author(s):  
D. K. Edwards
Keyword(s):  
Barometric Pressure ◽  
Flight Activity ◽  
Insect Species ◽  
Calliphora Vicina ◽  
Pressure Drops ◽  
Level Pressure ◽  
Previous Condition ◽  
Per Se ◽  
Pressure Changes ◽  
Experimental Pressure

The amount of flight activity of Calliphora vicina R.D. was monitored during (a) natural, diurnal, barometric pressure changes, and (b) experimental pressure changes of natural amounts and rates. Activity was increased by a change in trend from rising or level to falling pressure, or by two step-like drops of 1 millibar, each lasting 15 minutes, separated by 1 hour of level pressure. The change to falling pressure, not falling pressure per se. stimulated activity in C. vicina. Activity was little, if at all, affected by a change to rising pressure from a previous condition of falling or level pressure. With Calliphora vomitoria (L.) no effects of a changing pressure trend on activity were observed. These findings indicate that natural, and particularly prefrontal, pressure drops under certain conditions can influence the amount of activity of some insect species.

scholarly journals Predicting large experimental excess pressure drops for Boger fluids in contraction–expansion flow

2016 ◽  
Vol 230 ◽  
pp. 43-67 ◽  
Author(s):  
H.R. Tamaddon-Jahromi ◽  
I.E. Garduño ◽  
J.E. López-Aguilar ◽  
M.F. Webster
Keyword(s):  
Excess Pressure ◽  
Pressure Drops ◽  
Boger Fluids

scholarly journals Experimental pressure drops during the water flow into porous materials realized via additive manufacturing

2021 ◽  
Vol 2116 (1) ◽  
pp. 012059
Author(s):  
G Righetti ◽  
C Zilio ◽  
G Savio ◽  
R Meneghello ◽  
M Calati ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Pressure Drop ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Open Cell ◽  
Pressure Drops ◽  
Manufacturing Testing ◽  
Open Cell Foams ◽  
Experimental Pressure

Abstract Open-cell foams offer several interesting possibilities in numerous technological fields. In fact, they present high surface area to volume ratio as well as enhanced flow mixing and attractive stiffness and strength. However, their complete and reliable characterization has not been completed yet. In fact, there is still no a comprehensive work that relates all the foam geometrical characteristics to their heat transfer and pressure drop features. This paper is the very first outcome of a larger study that aims at realizing open-cell foams via additive manufacturing, testing them, then generating a simulation model based on the real geometries to numerically optimize each parameter. The present manuscript presents the construction of the open-foam via 3D printing and the experimental pressure drop measurements when water flows through the foam.

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