Correlation of Mobility Reduction of HPAM Solutions at High Velocity in Porous Medium with Ex-Situ Measurements of Elasticity

SPE Journal ◽  
2019 ◽  
Vol 25 (01) ◽  
pp. 465-480 ◽  
Author(s):  
Stephane Jouenne ◽  
Guillaume Heurteux
Keyword(s):  
Porous Medium ◽  
Flow Rate ◽  
Bulk Viscosity ◽  
Polymer Solutions ◽  
Shear Thinning ◽  
High Flow ◽  
Extensional Viscosity ◽  
Ex Situ ◽  
Flow Rates ◽  
Mobility Reduction

Summary When injected at high flow rates in a porous medium, polymer solutions exhibit a resistance to flow that is a signature of chain conformation and size. For biopolymers, which exist in solution as semirigid rods, mobility reduction follows the shear-thinning behavior measured in shear flow on a rheometer. For flexible coils, such as hydrolyzed polyacrylamide (HPAM), flow thickening is observed in a porous medium, whereas bulk viscosity presents a shear-thinning behavior. This difference is the result of the complex flow experienced in the porous medium, combined with the viscoelastic properties at large strains of the solutions. In this study, we investigate the effect of physicochemical parameters such as salinity, polymer concentration, molecular weight, and degradation state on the mobility reduction in a porous medium at high flow rates. All the experiments are performed on a short-length, 4-darcy sintered ceramic core. The bell shape of the mobility-reduction curves (mobility reduction vs. flow rate) is characterized by three parameters: the onset rate of flow thickening (QC), the maximum of mobility reduction (Rmmax), and the flow rate at which this maximum occurs (Qmax). Curves are rescaled by use of the two groups, Rm/Rmmax and β×Q, where β accounts for the shift in Qmax when physicochemical conditions are varied. After rescaling, all the normalized mobility-reduction curves are superposed. We show that the two parameters Rmmax and β are not correlated with the bulk viscosity of the solutions but rather with their elasticity evaluated through screen-factor measurement. This old and rough measurement, widely used in the enhanced-oil-recovery (EOR) community to evaluate “solution elasticity,” is an indirect measurement of the extensional viscosity of polymer solutions. The pertinence and the physical meaning of this rough measurement are assessed through comparison with measurements performed on a newly developed extensional viscometer [EVROC™ (Extensional Viscometer/Rheometer On a Chip), RheoSense, Inc., San Ramon, California, USA], which consists of measuring the pressure drop when the fluid is injected through a hyperbolic contraction (in which the strain rate is constant at the centerline). A correlation of “screen factor” vs. “extensional viscosity” is obtained. These results give some insight on the behavior of polymer solutions in injectivity conditions along with a method to characterize their elastic properties from bulk measurements. Finally, the inadequacy of traditional small-strain viscoelastic measurements to characterize the elastic behavior of polymer solutions at large strain is discussed.

Experimental Investigation of Pressure Fluctuations on Inner Wall of a Centrifugal Pump

2019 ◽  
Vol 36 (4) ◽  
pp. 401-410 ◽  
Author(s):  
Xiao-Qi Jia ◽  
Bao-Ling Cui ◽  
Zu-Chao Zhu ◽  
Yu-Liang Zhang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
High Flow ◽  
Low Flow ◽  
Centrifugal Pumps ◽  
Flow Rates ◽  
Pressure Distributions ◽  
Blade Passing Frequency

Abstract Affected by rotor–stator interaction and unstable inner flow, asymmetric pressure distributions and pressure fluctuations cannot be avoided in centrifugal pumps. To study the pressure distributions on volute and front casing walls, dynamic pressure tests are carried out on a centrifugal pump. Frequency spectrum analysis of pressure fluctuation is presented based on Fast Fourier transform and steady pressure distribution is obtained based on time-average method. The results show that amplitudes of pressure fluctuation and blade-passing frequency are sensitive to the flow rate. At low flow rates, high-pressure region and large pressure gradients near the volute tongue are observed, and the main factors contributing to the pressure fluctuation are fluctuations in blade-passing frequency and high-frequency fluctuations. By contrast, at high flow rates, fluctuations of rotating-frequency and low frequencies are the main contributors to pressure fluctuation. Moreover, at low flow rates, pressure near volute tongue increases rapidly at first and thereafter increases slowly, whereas at high flow rates, pressure decreases sharply. Asymmetries are observed in the pressure distributions on both volute and front casing walls. With increasing of flow rate, both asymmetries in the pressure distributions and magnitude of the pressure decrease.

scholarly journals An In Vitro Evaluation of the Red Cell Damage and Hemocompatibility of Different Central Venous Catheters

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Alojz Ihan ◽  
Stefan Grosek ◽  
David Stubljar
Keyword(s):  
Blood Cell ◽  
Flow Rate ◽  
Blood Cells ◽  
Cell Damage ◽  
Central Venous Catheters ◽  
High Flow ◽  
High Flow Rate ◽  
Low Flow ◽  
Central Venous ◽  
Flow Rates

Background. The aim of our study was to evaluate the damaging impact of characteristics of the central venous catheters (CVCs) on red blood cells. Methods. CVCs from three different manufacturers were analyzed, including the presence of coating, tunnel geometry, length, lumen diameter, and number of lumens with two respective flow rates (33 mL/min and 500 mL/min). Blood cell damage was defined by analyzing microparticle (MP) and hematologic analysis. MPs were isolated by ultracentrifugation of erythrocyte concentrate and analyzed on a flow cytometer. Results. Characteristics of catheters were not associated with blood cell damage at a low flow rate but showed an effect with a high flow rate. CVCs with a polyhexanide methacrylate coating have caused statistically less blood cell damage than noncoated CVCs. The length of lumens, diameter, and geometry of the tunnel showed no differences in blood cell damage. Meanwhile, the number of lumens was predicted to have a greater effect on the erythrocyte damage, which was revealed with the formation of MPs and hematological parameters. CVCs with five lumens caused significantly less damage to the blood cells than CVCs with a single lumen. Moreover, a high flow rate of 500 mL/min caused less damage to the blood cells than a low rate of 33 mL/min. Conclusion. Properties of CVCs are an important factor for quality patient care, especially when transfusing blood with high flow rates, as we want to provide a patient with high-quality blood with as few damaged cells as possible.

Rheological Effects of Blood in a Nonplanar Distal End-to-Side Anastomosis

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Qian-Qian Wang ◽  
Bao-Hong Ping ◽  
Qing-Bo Xu ◽  
Wen Wang
Keyword(s):  
Flow Rate ◽  
Stokes Equations ◽  
Bypass Graft ◽  
High Flow ◽  
Secondary Flows ◽  
Newtonian Fluids ◽  
Low Flow ◽  
Flow Rates ◽  
Flow Recirculation ◽  
Low Flow Rate

This study investigates rheological effects of blood on steady flows in a nonplanar distal end-to-side anastomosis. The shear-thinning behavior of blood is depicted by a Carreau–Yasuda model and a modified power-law model. To explore effects of nonplanarity in vessel geometry, a curved bypass graft is considered that connects to the host artery with a 90deg out-of-plane curvature. Navier–Stokes equations are solved using a finite volume method. Velocity and wall shear stress (WSS) are compared between Newtonian and non-Newtonian fluids at different flow rates. At low flow rate, difference in axial velocity profiles between Newtonian and non-Newtonian fluids is significant and secondary flows are weaker for non-Newtonian fluids. At high flow rate, non-Newtonian fluids have bigger peak WSS and WSS gradient. The size of the flow recirculation zone near the toe is smaller for non-Newtonian fluids and the difference is significant at low flow rate. The nonplanar bypass graft introduces helical flow in the host vessel. Results from the study reveal that near the bed, heel, and toe of the anastomotic junction where intimal hyperplasia occurs preferentially, WSS gradients are all very big. At high flow rates, WSS gradients are elevated by the non-Newtonian effect of blood but they are reduced at low flow rates. At these locations, blood rheology not only affects the WSS and its gradient but also secondary flow patterns and the size of flow recirculation near the toe. This study reemphasizes that the rheological property of blood is a key factor in studying hemodynamic effects on vascular diseases.

scholarly journals Application of High Flow Rate Gas in the Process of Argon Blowing Trough Steel

2017 ◽  
Vol 62 (2) ◽  
pp. 905-910
Author(s):  
T. Merder ◽  
J. Pieprzyca ◽  
M. Warzecha ◽  
P. Warzecha
Keyword(s):  
Numerical Simulations ◽  
Flow Rate ◽  
High Flow ◽  
High Flow Rate ◽  
Water Model ◽  
Steel Ladle ◽  
Metal Bath ◽  
Flow Rates ◽  
Nominal Capacity ◽  
Additional Support

AbstractThe article demonstrates results of modelling research tests concerning the analysis of possibilities of blowing gas into the metal bath at high flow rates in a steel ladle with a nominal capacity of 50 Mg. Various configurations concerning of gas introduction into the steel ladle were analysed. There were considered cases of blowing into the metal bath via one, two or three purging plugs, being installed on the bottom and via additional support for blowing the gas from the top through the lance.Results obtained from the water model of the reactor were verified with the results of numerical simulations.

Acoustic Measurements From an Automotive Centrifugal Compressor With a Switchable Dual-Port Casing Treatment for Extended Operating Range

2016 ◽  
Author(s):  
Rick Dehner ◽  
Ahmet Selamet ◽  
Michael Steiger ◽  
Harold Sun ◽  
Dave Hanna ◽  
...  
Keyword(s):  
Flow Rate ◽  
Broadband Noise ◽  
High Flow ◽  
Low Flow ◽  
Acoustic Measurements ◽  
Suction Surface ◽  
Flow Rates ◽  
Casing Treatment ◽  
Operating Range ◽  
Operating Region

An effective measure to improve the surge margin of a centrifugal compressor, without sacrificing efficiency, is to implement a recirculating casing treatment inside the compressor cover. However, introduction of an additional sound propagation path directly over the rotating impeller blades exposes the inherently unsteady internal flow-field as an added potential noise source, which is of concern for automotive applications. The present study conducts performance and acoustic measurements of a new compressor which was designed to achieve high isentropic efficiency over a wide flow range, featuring an impeller with splitter blades and a vaneless diffuser. A dual-port active casing treatment (ACT) was also incorporated into the compressor cover to independently extend both the low and high flow rate operating regions of the compressor. The slot of the first (surge) port is positioned between the main and splitter blades of the impeller, similar to passive casing treatments that are already widely adopted. This port extends the low-flow boundary of the compressor operating range by reducing flow separation on the suction surface of the main blades near the shroud. The slot of the second (choke) port is located just behind the splitter blades, and it is studied in both the open and closed positions. This second port allows for increased air flow near choke, due to the slot position just downstream of the aerodynamic throat of the compressor. The current ACT design leaves the surge port open at all times, while the choke port is only opened when the compressor operates near choke conditions. In addition to comparing experimental results from this new compressor in both configurations (choke port open and closed), measurements from a comparable (baseline) compressor without splitter blades and a single-port shroud are utilized to assess the acoustics of the new design. Acoustic measurements were completed over the low to mid-speed operating range, which is a region heavily weighted in customer drive cycles for light and medium duty vehicles. The conscientious design of the impeller and surge slot of the new compressor to minimize flow separation on the suction surface of the inducer blades is shown to not only improve efficiency and extend the low-flow operating range, but (with the choke port closed) broadband noise is significantly reduced in the mid to high flow rate operating region. At low flow rates, the new compressor (with the choke port closed) is slightly louder than the baseline compressor at the inlet duct measurement location, but essentially equal to the baseline compressor at the external microphone location near the compressor inlet duct opening. When the choke port of the new compressor is open, broadband noise increases slightly relative to the closed configuration. More importantly, the peak sound pressure level at (main) blade-pass frequency is reduced by opening the choke port, and the operating region of elevated tonal noise shifts from mid to high flow rates.

scholarly journals Efficacy and Safety of Two Different Flow Rates of Nasal High-Flow Therapy in Preterm Neonates ≥28 Weeks of Gestation: A Randomized Controlled Trial

2021 ◽  
Author(s):  
Haribalakrishna Balasubramanian ◽  
Sachin Sakharkar ◽  
Swati Majarikar ◽  
Lakshmi Srinivasan ◽  
Nandkishor S. Kabra ◽  
...  
Keyword(s):  
Flow Rate ◽  
Controlled Trial ◽  
High Flow ◽  
Respiratory Support ◽  
Preterm Neonates ◽  
Flow Rates ◽  
Randomized Controlled ◽  
Flow Group ◽  
Nasal High Flow Therapy ◽  
Nasal Flow

Objective The study aimed to compare the efficacy and safety of two different nasal high-flow rates for primary respiratory support in preterm neonates Study Design In this single-center, double-blinded randomized controlled trial, preterm neonates ≥28 weeks of gestation with respiratory distress from birth were randomized to treatment with either increased nasal flow therapy (8–10 L/min) or standard nasal flow therapy (5–7 L/min). The primary outcome of nasal high-flow therapy failure was a composite outcome defined as the need for higher respiratory support (continuous positive airway pressure [CPAP] or mechanical ventilation) or surfactant therapy. Results A total of 212 neonates were enrolled. Nasal high-flow failure rate in the increased flow group was similar to the standard flow group (22 vs. 29%, relative risk = 0.81 [95% confidence interval: 0.57–1.15]). However, nasal flow rate escalation was significantly more common in the standard flow group (64 vs. 43%, p = 0.004). None of the infants in the increased flow group developed air leak syndromes. Conclusion Higher nasal flow rate (8–10 L/min) when compared with lower nasal flow rate of 5 to 7 L/min did not reduce the need for higher respiratory support (CPAP/mechanical ventilation) or surfactant therapy in moderately and late preterm neonates. However, initial flow rates of 5 L/min were not optimal for most preterm infants receiving primary nasal flow therapy. Key Points

Novel external stenting for reconstruction of high flow arteriovenous fistula

2021 ◽  
pp. 112972982110155
Author(s):  
Vladimir Matoussevitch ◽  
Egan Kalmykov ◽  
Robert Shahverdyan
Keyword(s):  
Flow Rate ◽  
Cardiac Remodeling ◽  
Primary Patency ◽  
High Flow ◽  
Cobalt Chromium ◽  
Mean Flow ◽  
Flow Rates ◽  
Vein Segment ◽  
The Mean

Background: High-flow arteriovenous fistulae (HF-AVF) may lead to adverse cardiac remodeling in hemodialysis patients. We have investigated whether a novel external stent is safe and effective in reducing and stabilizing flow rates during a 1-year follow-up after HF-AVF reconstruction. Methods: All patients with HF-AVF (access flow rate ⩾ 1500 ml/min), who underwent HF-AVF reconstruction with external stenting in two centers between June 2018 and May 2020, were included in this retrospective analysis. During HF-AVF reconstruction, the dilated vein segment was resected, underwent volume reduction, and was externally stabilized using a braided cobalt-chromium external stent. AVF flow rates were assessed preoperatively, intraoperatively, and at follow up visits using duplex ultrasound. Results: Forty-three HF-AVFs in 42 patients were reconstructed and supported with an external stent (mean age 49 years, range 20–86 years; 74% men). Fifty-one percent were forearm AVFs, 49% were upper arm. The mean preoperative flow rate was 2622 ± 893 ml/min (range: 1500–6000 ml/min) and was decreased to 710 ± 221 ml/min (range: 300–1300 ml/min) intra-operatively after HF-AVF reconstruction. At 6 and 12-months follow-up, the mean flow rates were 1132 ± 320 ml/min (range: 470–1700 ml/min) and 1453 ± 888 ml/min (range: 300–3800 ml/min), respectively. Recurrence of high flow (>1500 ml/min) occurred in 16% and 25% of the patients at 6 and 12 months and primary patency rates were 86% and 70%, respectively. Conclusions: This early experience with novel external stenting for HF-AVF reconstruction demonstrates that it is a safe and effective method for reducing and stabilizing flow rates up to 1-year post procedure. Additional studies are required to evaluate the durability of this procedure over the longer term and assess its effect on cardiac remodeling.

scholarly journals From Darcy to Gaussian to fully mobilised grain flow in a confined channel

2021 ◽  
Vol 249 ◽  
pp. 03041
Author(s):  
Miles Morgan ◽  
Bjørnar Sandnes
Keyword(s):  
Flow Rate ◽  
High Flow ◽  
Gradual Transition ◽  
Velocity Measurements ◽  
Flow Rates ◽  
Gaussian Profile ◽  
Grain Flow ◽  
Flow Through ◽  
Self Similar ◽  
Confined Channel

Fluid-driven grain flow through a confined channel filled with non-buoyant grains is herein observed to exist in three regimes according to total imposed flow rate. (1) At low imposed flow rates, no grain flow occurs as the fluid stress is insufficient to mobilise the grains and Darcy flow is observed. (2) At a sufficient imposed flow rate, grains begin to flow at the top of the channel with self-similar Gaussian velocity profiles that become faster and encroach deeper into the channel with increased flow rate. (3) At high flow rates, significant grain flow occurs at the base of the channel, distorting the Gaussian profile, resulting in a gradual transition towards a more symmetric, full-channel flow. Each regime, and the transitions between them, is discussed in relation to experimental grain velocity measurements.

In Situ Nitrogen and Aluminum Doping in Migration Enhanced Embedded Epitaxial Growth of 4H-SiC

2008 ◽  
Vol 600-603 ◽  
pp. 175-178 ◽  
Author(s):  
Adolf Schöner ◽  
Naohiro Sugiyama ◽  
Yuuichi Takeuchi ◽  
Rajesh Kumar Malhan
Keyword(s):  
High Temperature ◽  
Epitaxial Growth ◽  
Flow Rate ◽  
Nitrogen Doping ◽  
High Flow ◽  
Memory Effects ◽  
Aluminum Doping ◽  
Flow Rates ◽  
Aluminum Precursor

The in-situ doping of aluminum and nitrogen in migration enhanced embedded epitaxy (ME3) is investigated with the aim to apply it to the realization and fabrication of all-epitaxial, normally-off 4H-SiC JFET devices. This ME3 process consists of the epitaxial growth of an n-doped channel and a highly p-doped top gate in narrow trenches. We found that the nitrogen doping in the n-channel (a-face) is a factor 1.5 higher than layers grown with the same process on Si-face wafers. Due to the low C/Si ratio and the low silane flow rate used in the ME3 process, the growth of the p-doped top gate needs high flow rates of the aluminum precursor trimethylaluminum for several hours, which contaminates the CVD reactor and causes aluminum memory effects. These aluminum memory effects can be reduced by an extra high temperature bake-out run.

Electrolyte levels of rat salivary secretions in relation to fluid-flow rate

1960 ◽  
Vol 199 (1) ◽  
pp. 55-58 ◽  
Author(s):  
C. A. Schneyer ◽  
L. H. Schneyer
Keyword(s):  
Flow Rate ◽  
High Flow ◽  
Fluid Flow Rate ◽  
Parotid Saliva ◽  
Subsequent Increase ◽  
Flow Rates ◽  
High K ◽  
Rat Parotid ◽  
Transient Elevation ◽  
Low K

Rat parotid, submaxillary and sublingual salivas, collected directly from the respective gland ducts following a single stimulatory dose of pilocarpine, show widely divergent Na and K concentrations at high flow rates. Parotid secretion shows high Na and low K levels; submaxillary, low Na and high K; sublingual has intermediate levels of both electrolytes. Changes in flow rate and duration of secretion modify Na-K balance. With decreasing flow rate and increasing duration of flow, Na level of parotid secretion decreases, whereas Na of submaxillary increases before decreasing. Concurrently, K in these secretions first shows a transient elevation followed by a decrease and subsequent increase. Parotid saliva is usually isotonic or slightly hypertonic to serum at high flow rates; submaxillary and sublingual secretions are generally hypotonic at all flow rates. Some correlation between electrolyte levels of gland and secretion seems apparent.

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