Nonlinear Flow Rate Response to Pumping Frequency and Reduced Hemolysis in the Drastically Under-Occluded Pulsatile Roller Pump

2016 ◽  
Vol 41 (2) ◽  
pp. 178-185 ◽  
Author(s):  
Choon Hwai Yap ◽  
Chang Quan Lai ◽  
Ivan Guang Hui Loh ◽  
Thaddaeus Zhongren Ong
Keyword(s):  
Flow Rate ◽  
Nonlinear Flow ◽  
Roller Pump

Oscillatory forcing of flow through porous media. Part 1. Steady flow

2002 ◽  
Vol 465 ◽  
pp. 213-235 ◽  
Author(s):  
D. R. GRAHAM ◽  
J. J. L. HIGDON
Keyword(s):  
Porous Media ◽  
Flow Rate ◽  
Stokes Equations ◽  
Nonlinear Flow ◽  
Navier Stokes ◽  
Full Time ◽  
Inertial Effects ◽  
Mean Flow ◽  
Navier Stokes Equations ◽  
The Mean

Oscillatory forcing of a porous medium may have a dramatic effect on the mean flow rate produced by a steady applied pressure gradient. The oscillatory forcing may excite nonlinear inertial effects leading to either enhancement or retardation of the mean flow. Here, in Part 1, we consider the effects of non-zero inertial forces on steady flows in porous media, and investigate the changes in the flow character arising from changes in both the strength of the inertial terms and the geometry of the medium. The steady-state Navier–Stokes equations are solved via a Galerkin finite element method to determine the velocity fields for simple two-dimensional models of porous media. Two geometric models are considered based on constricted channels and periodic arrays of circular cylinders. For both geometries, we observe solution multiplicity yielding both symmetric and asymmetric flow patterns. For the cylinder arrays, we demonstrate that inertial effects lead to anisotropy in the effective permeability, with the direction of minimum resistance dependent on the solid volume fraction. We identify nonlinear flow phenomena which might be exploited by oscillatory forcing to yield a net increase in the mean flow rate. In Part 2, we take up the subject of unsteady flows governed by the full time-dependent Navier–Stokes equations.

DETERMINATION OF A HORIZONTAL WELL FLOW-RATE FOR THE CONDITIONS OF A NONLINEAR FLOW

2019 ◽  
pp. 52-55
Author(s):  
O.N. Shevchenko ◽  
◽  
I.A. Kibalenko ◽  
O.Yu. Kashnikov ◽  
◽  
...  
Keyword(s):  
Flow Rate ◽  
Horizontal Well ◽  
Nonlinear Flow

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.

scholarly journals Effect of Lower Surface Roughness on Nonlinear Hydraulic Properties of Fractures

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jinglong Li ◽  
Xianghui Li ◽  
Bo Zhang ◽  
Bin Sui ◽  
Pengcheng Wang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Flow Rate ◽  
Stokes Equations ◽  
Flow Regimes ◽  
Lower Surface ◽  
Nonlinear Flow ◽  
Hydraulic Pressure

This study investigates the effect of fracture lower surface roughness on the nonlinear flow behaviors of fluids through fractures when the aperture fields are fixed. The flow is modeled with hydraulic pressure drop = 10 − 4 ~ 10 5   Pa / m by solving the Navier-Stokes equations based on rough fracture models with lower surface roughness varying from JRC = 1 to JRC = 19 . Here, JRC represents joint roughness coefficient. The results show that the proposed numerical method is valid by comparisons between numerically calculated results with theoretical values of three parallel-plate models. With the increment of hydraulic pressure drop from 10-4 to 105 Pa/m spanning ten orders of magnitude, the flow rate increases with an increasing rate. The nonlinear relationships between flow rate and hydraulic pressure drop follow Forchheimer’s law. With increasing the JRC of lower surfaces from 1 to 19, the linear Forchheimer coefficient decreases, whereas the nonlinear Forchheimer coefficient increases, both following exponential functions. However, the nonlinear Forchheimer coefficient is approximately three orders of magnitude larger than the linear Forchheimer coefficient. With the increase in Reynolds number, the normalized transmissivity changes from constant values to decreasing values, indicating that fluid flow transits from linear flow regimes to nonlinear flow regimes. The critical Reynolds number that quantifies the onset of nonlinear fluid flow ranges from 21.79 to 185.19.

scholarly journals Numerical Simulation of the Nonlinear Flow Properties in Self-Affine Aperture-Based Fractures

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xin Zhou ◽  
Jianlong Sheng ◽  
Ruili Lu ◽  
Zuyang Ye ◽  
Wang Luo
Keyword(s):  
Fractal Dimension ◽  
Standard Deviation ◽  
Flow Rate ◽  
Empirical Relationship ◽  
Nonlinear Coefficient ◽  
Nonlinear Flow ◽  
Flow Properties ◽  
Navier Stokes Equation ◽  
Linear Coefficient ◽  
Hydraulic Aperture

In order to study the effect of fracture geometry on the nonlinear flow properties in aperture-based fractures, a fractal model based on the self-affinity is proposed to characterize the three-dimensional geometry of rough-walled fractures. By solving the N–S (Navier–Stokes) equation directly, the relationships between the Forchheimer-flow characteristics, fractal dimension, and standard deviation of the aperture have been obtained. The Forchheimer equation is validated to describe the nonlinear relationship between flow rate and pressure gradient. For lower flow rate, the influence of the fractal dimension almost can be ignored, but the linear coefficient increases and the hydraulic aperture decreases with increasing standard deviation of the aperture, respectively. For larger flow rate, the nonlinear coefficient increases with the growth of the standard deviation of the aperture and fractal dimension. Thus, an empirical relationship between the nonlinear coefficient, fractal dimension, and standard deviation of aperture is proposed. In addition, the critical Reynolds number decreases with the increase of the standard deviation of the aperture and the fractal dimension, and the numerical results are generally consistent with the experimental data.

Tubing Spallation in Extracorporeal Circuits. An in Vitro Study Using an Electronic Particle Counter

1992 ◽  
Vol 15 (4) ◽  
pp. 222-228 ◽  
Author(s):  
J.C. Briceño T. ◽  
T. M. Runge
Keyword(s):  
Flow Rate ◽  
In Vitro Study ◽  
Blood Flow Rate ◽  
Vitro Study ◽  
Occlusion Pressure ◽  
Roller Pump ◽  
Extracorporeal Circuits ◽  
Electronic Particle Counter ◽  
Particle Counts

The roller pump is the most common pumping device used in extracorporeal circulation (ECC). The interaction between the roller and tubing causes tubing spallation. Spallation has been associated with complications in ECC. Previous spallation studies present mixed results, including a decrease in the number of circulating particles. The objective of this work is to perform an in vitro study of tubing spallation which elucidates the causes of the particle sequestration, and the effect of tubing material, blood flow rate and duration of the procedure upon spallation. A sampling method minimizing background counts was devised. Silicone and PVC tubing were tested under normal and tight occlusion pressure at typical cardiopulmonary bypass and hemodialysis flow rates, for circulating times up to 4 h. Occlusion pressure and flow rate highly influenced the amount of spallation produced. Particle sequestration was noted and aggregation of the plastic particles was demonstrated. We conclude that, at least in vitro, aggregation causes the decrease in the particle counts and the misleading results obtained in most spallation studies using a Coulter counter.

Does an Open Recirculation Line Affect the Flow Rate and Pressure in a Neonatal Extracorporeal Life Support Circuit With a Centrifugal or Roller Pump?

2016 ◽  
Vol 41 (1) ◽  
pp. 70-75 ◽  
Author(s):  
Shigang Wang ◽  
Shannon B. Spencer ◽  
Karl Woitas ◽  
Kristen Glass ◽  
Allen R. Kunselman ◽  
...  
Keyword(s):  
Flow Rate ◽  
Life Support ◽  
Extracorporeal Life Support ◽  
Roller Pump

Non-Darcian Air Flow in Wood. Part 2. Nonlinear Flow

Holzforschung ◽  
1999 ◽  
Vol 53 (1) ◽  
pp. 77-84 ◽  
Author(s):  
J. Lu ◽  
S. Avramidis
Keyword(s):  
Flow Rate ◽  
Ponderosa Pine ◽  
Air Flow ◽  
Douglas Fir ◽  
Nonlinear Flow ◽  
Red Oak ◽  
Red Alder ◽  
Flow Rates ◽  
Relationship Analysis ◽  
Mean Pressure

Summary In this study, permeability measurements and flow rate-pressure-relationship analysis were carried out to determine whether non-Darcian flow due to nonlinear flow is present during air flow through red oak and red alder heartwood, and ponderosa pine and Douglas-fir sapwood. The results indicated that there was no evidence of nonlinear flow in red alder, ponderosa pine, and Douglas-fir throughout the entire range of flow rates, and for red oak at flow rates below 19.57 cm3/s. At higher flow rates, the results for red oak showed that the superficial specific permeability at the mean pressure of 50kPa decreased with the increase of the flow rates, and the equation relating pressure drop and flow rate at a given mean pressure of 50 kPa involved both a linear and quadratic dependence, thus demonstrating the presence of nonlinear flow components in wood. The calculated Reynolds number that was in the range of 0.263 to 1.05, further suggested that the nonlinear flow found in red oak heartwood at higher flow rates was probably nonlinear laminar flow due to the kinetic-energy losses occurring in the curved openings.

A Novel Reconstitution Method for Inducing the Formation of Regular 2-Dimensional Arrays of Membrane Proteins and Lipids

1988 ◽  
Vol 46 ◽  
pp. 152-153 ◽  
Author(s):  
A. Engel ◽  
A. Holzenburg ◽  
K. Stauffer ◽  
J. Rosenbusch ◽  
U. Aebi
Keyword(s):  
Membrane Proteins ◽  
Flow Rate ◽  
Lipid Membranes ◽  
Functional Characterization ◽  
Dimensional Structure ◽  
Electron Crystallography ◽  
Peltier Element ◽  
Protein Ratio ◽  
Precise Control ◽  
3 Dimensional

Reconstitution of solubilized and purified membrane proteins in the presence of phospholipids into vesicles allows their functions to be studied by simple bulk measurements (e.g. diffusion of differently sized solutes) or by conductance measurements after transformation into planar membranes. On the other hand, reconstitution into regular protein-lipid arrays, usually forming at a specific lipid-to-protein ratio, provides the basis for determining the 3-dimensional structure of membrane proteins employing the tools of electron crystallography.To refine reconstitution conditions for reproducibly inducing formation of large and highly ordered protein-lipid membranes that are suitable for both electron crystallography and patch clamping experiments aimed at their functional characterization, we built a flow-dialysis device that allows precise control of temperature and flow-rate (Fig. 1). The flow rate is generated by a peristaltic pump and can be adjusted from 1 to 500 ml/h. The dialysis buffer is brought to a preselected temperature during its travel through a meandering path before it enters the dialysis reservoir. A Z-80 based computer controls a Peltier element allowing the temperature profile to be programmed as function of time.

Novel epoxy/anhydride alternatives for biological electron microscopy: Physical and performance characteristis of embed 812 and LX 112 in combination with NSA/NMA/DMAE

1989 ◽  
Vol 47 ◽  
pp. 1000-1001
Author(s):  
Joe A. Mascorro ◽  
Gerald S. Kirby
Keyword(s):  
Electron Microscopy ◽  
Flow Rate ◽  
Succinic Anhydride ◽  
Volume Flow Rate ◽  
Mass Density ◽  
Uranyl Acetate ◽  
Volume Flow ◽  
Base Resin ◽  
And Performance ◽  
Acid Anhydrides

Embedding media based upon an epoxy resin of choice and the acid anhydrides dodecenyl succinic anhydride (DDSA), nadic methyl anhydride (NMA), and catalyzed by the tertiary amine 2,4,6-Tri(dimethylaminomethyl) phenol (DMP-30) are widely used in biological electron microscopy. These media possess a viscosity character that can impair tissue infiltration, particularly if original Epon 812 is utilized as the base resin. Other resins that are considerably less viscous than Epon 812 now are available as replacements. Likewise, nonenyl succinic anhydride (NSA) and dimethylaminoethanol (DMAE) are more fluid than their counterparts DDSA and DMP- 30 commonly used in earlier formulations. This work utilizes novel epoxy and anhydride combinations in order to produce embedding media with desirable flow rate and viscosity parameters that, in turn, would allow the medium to optimally infiltrate tissues. Specifically, embeding media based on EmBed 812 or LX 112 with NSA (in place of DDSA) and DMAE (replacing DMP-30), with NMA remaining constant, are formulated and offered as alternatives for routine biological work.Individual epoxy resins (Table I) or complete embedding media (Tables II-III) were tested for flow rate and viscosity. The novel media were further examined for their ability to infilftrate tissues, polymerize, sectioning and staining character, as well as strength and stability to the electron beam and column vacuum. For physical comparisons, a volume (9 ml) of either resin or media was aspirated into a capillary viscocimeter oriented vertically. The material was then allowed to flow out freely under the influence of gravity and the flow time necessary for the volume to exit was recored (Col B,C; Tables). In addition, the volume flow rate (ml flowing/second; Col D, Tables) was measured. Viscosity (n) could then be determined by using the Hagen-Poiseville relation for laminar flow, n = c.p/Q, where c = a geometric constant from an instrument calibration with water, p = mass density, and Q = volume flow rate. Mass weight and density of the materials were determined as well (Col F,G; Tables). Infiltration schedules utilized were short (1/2 hr 1:1, 3 hrs full resin), intermediate (1/2 hr 1:1, 6 hrs full resin) , or long (1/2 hr 1:1, 6 hrs full resin) in total time. Polymerization schedules ranging from 15 hrs (overnight) through 24, 36, or 48 hrs were tested. Sections demonstrating gold interference colors were collected on unsupported 200- 300 mesh grids and stained sequentially with uranyl acetate and lead citrate.

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