Morphological dynamics of ureteral transport. II. Peristaltic patterns in relation to flow rate

1989 ◽  
Vol 256 (1) ◽  
pp. R29-R34 ◽  
Author(s):  
L. Ohlson
Keyword(s):  
Flow Rate ◽  
Flow Regimes ◽  
High Flow ◽  
Low Flow ◽  
Contact Period ◽  
Tube Flow ◽  
Flow Rates ◽  
Open Tube ◽  
Normal Human ◽  
Points Of Resistance

To study in the human the conditions for the flow regimes inherent in urinary systems with a dependence of the contraction interval on urine flow rate (boluses-in-contact, leaky-bolus, and open-tube flow regimes), 50 urinary systems were examined at low and high flow rates. Morphometry and volumetry were applied to eight urinary systems. The bolus frequently contacted the preceding contraction ring but the mechanisms differed categorically from that conventionally postulated. Thus the contraction interval proved independent of flow rate, leading to boluses in contact not only at high but also at low flow rates, which is impossible in flow-dependent urinary systems. Likewise, contact proved possible with small as well as large boluses. Furthermore, the contact was invariably interrupted at the points of resistance to flow, the total contact period being only 4% of the ureteral transit. Leaky-bolus flow and open-tube flow were absent. The flow regimes as conventionally defined thus proved to be absent from and inconsistent with normal human urinary transport.

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.

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 Influence of flow rate, fluid temperature, and extension line on Hotline and S-line heating capability: an in vitro study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Hosu Kim ◽  
Tae Kyong Kim ◽  
Sukha Yoo ◽  
Jin-Tae Kim
Keyword(s):  
Flow Rate ◽  
Room Temperature ◽  
In Vitro Study ◽  
High Flow ◽  
High Flow Rate ◽  
Low Flow ◽  
Fluid Temperature ◽  
Flow Rates ◽  
Fluid Warmer

Abstract Background A fluid warmer can prevent hypothermia during the perioperative period. This study evaluated the heating capabilities of Hotline and Barkey S-line under different flow rates and initial fluid temperatures, as well as after the extension line installation. Methods We measured the temperature of a 0.9% sodium chloride solution at the fluid warmer outlet (TProx) and the extension line end (TDistal) with three different initial fluid temperatures (room, warm, and cold) and two flow rates (250 ml/hr and 100 mL/hr). Results At a 250 ml/hr flow rate, the TProx and TDistal values were observed to be higher in Hotline than in S-line when using room-temperature or cold fluid. Administering of the warm fluid at the same flow rate significantly increased the TProx and TDistal values in S-line more than the cold and room-temperature fluids. At flow rates of 100 ml/hr, TDistal values were significantly lower than TProx values in both devices regardless of the initial fluid temperature. Conclusions Hotline outperformed S-line for warming fluids at a high flow rate with cold or room-temperature fluids. Administering warm fluid in S-line prevented a decrease in the fluid temperature at a high flow rate. However, at a low flow rate, the fluid temperature significantly decreased in both devices after passing through an extension line.

High Flow Rate Circulating Tumor Cell Capture Device

2011 ◽  
Author(s):  
Taehyun Park ◽  
Daniel Sangwon Park ◽  
Michael C. Murphy
Keyword(s):  
Flow Rate ◽  
Early Stage ◽  
Human Peripheral Blood ◽  
Capture Rate ◽  
Microfluidic Devices ◽  
High Flow ◽  
High Flow Rate ◽  
Low Flow ◽  
Cell Capture ◽  
Flow Rates

Circulating tumor cells (CTCs) may become a new foundation for early stage cancer diagnosis requiring minimal patient effort [1]. This approach can overcome the limitations of current diagnostic technologies, including computer-aided tomography (CT), magnetic resonance imaging (MRI), X-ray mammography, and ultrasound (UR) which can detect only highly calcified tumors at relatively high cost. Several studies have demonstrated CTC capture using microfluidic devices to identify the presence of human breast cancer, and the CellSearch™ immunomagnetic system (Johnson & Johnson, New Brunswick, NJ) is approved by the Food and Drug Administration (FDA) for monitoring post-treatment therapy, but all of the systems reported have either a long diagnosis time or unacceptable capture rates [2, 3]. CTCs in human peripheral blood are very rare events, typically 1 ∼ 2 CTCs in 1 mL of circulating blood. This low concentration of CTCs requires a large sample volume (∼7.5 mL) to ensure detection. However, current affinity-based microfluidic devices for cell capture usually operate at very low flow rates to increase the capture rate. Therefore, developing high flow rate microfluidic devices for CTC capture is essential and challenging. A new concept of high flow rate device is introduced, simulated, and tested at high flow rates.

Spray Washing of Tomatoes with Chlorine Dioxide To Minimize Salmonella on Inoculated Fruit Surfaces and Cross-Contamination from Revolving Brushes†

2009 ◽  
Vol 72 (12) ◽  
pp. 2448-2452 ◽  
Author(s):  
STEVEN PAO ◽  
D. FRANK KELSEY ◽  
WILBERT LONG
Keyword(s):  
Antimicrobial Agent ◽  
Flow Rate ◽  
Chlorine Dioxide ◽  
Salmonella Enterica ◽  
High Flow ◽  
High Flow Rate ◽  
Low Flow ◽  
Cross Contamination ◽  
Flow Rates ◽  
Log Reduction

Chlorine dioxide (ClO2) is an antimicrobial agent available for commercial produce washing. This study examined the efficacy of ClO2 at 5 parts per million (ppm) during spray washing of tomatoes (5.0 ml/s per fruit) for preventing Salmonella enterica transfer from inoculated roller brushes to fruit and wash runoff. Furthermore, the sanitizing effects of ClO2 during spray washing at low and high flow rates (5.0 and 9.3 ml/s per fruit, respectively) on tomato surfaces (nonstem scar areas) with either newly introduced (wet) or overnight air-dried Salmonella inocula were investigated. Salmonella transfer from contaminated brushes to fruit surfaces was reduced 2.1 ± 0.6 or 4.7 ± 0.2 log cycles after spray washing with water for 40 s or with the ClO2 solution for 10 s, respectively. Cross-contamination of Salmonella from brushes to wash runoff during fruit washing for 60 s decreased 5.9 ± 0.3 log cycles when ClO2 was used. Fruit washing using contaminated brushes and low flow-rate washing with either water or ClO2 solution for 10 s reduced newly introduced Salmonella on fruit surfaces by 1.7 ± 0.6 or 5.1 ± 0.3 log cycles, respectively. For fruit surfaces with air-dried inocula, washing with water and using uncontaminated brushes for 10 to 40 s reduced Salmonella by 3.2 ± 0.3 to 3.4 ± 0.4 log cycles; and the reduction was significantly improved by using ClO2, high flow rate, or a longer washing time. Washing with ClO2 at tested flow rates for 10 to 60 s resulted in a 4.4 ± 0.6 to 5.2 ± 0.1 log reduction of air-dried Salmonella on fruit surfaces.

scholarly journals Spheres in the vicinity of a bifurcation: elucidating the Zweifach–Fung effect

2011 ◽  
Vol 674 ◽  
pp. 359-388 ◽  
Author(s):  
V. DOYEUX ◽  
T. PODGORSKI ◽  
S. PEPONAS ◽  
M. ISMAIL ◽  
G. COUPIER
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Volume Fraction ◽  
Initial Distribution ◽  
High Flow ◽  
High Flow Rate ◽  
Low Flow ◽  
Two Dimensional ◽  
Flow Rates ◽  
Low Flow Rate

The problem of the splitting of a suspension in bifurcating channels divided into two branches of non-equal flow rates is addressed. As has long been observed, in particular in blood flow studies, the volume fraction of particles generally increases in the high-flow-rate branch and decreases in the low-flow-rate branch. In the literature, this phenomenon is sometimes interpreted as the result of some attraction of the particles towards this high-flow-rate branch. In this paper, we focus on the existence of such an attraction through microfluidic experiments and two-dimensional simulations and show clearly that such an attraction does not occur but is, on the contrary, directed towards the low-flow-rate branch. Arguments for this attraction are given and a discussion on the sometimes misleading arguments found in the literature is given. Finally, the enrichment of particles in the high-flow-rate branch is shown to be mainly a consequence of the initial distribution in the inlet branch, which shows necessarily some depletion near the walls.

scholarly journals Influence of flow rate, fluid temperature, and extension line on Hotline and S-line heating capability: an in vitro study

2020 ◽  
Author(s):  
Hosu Kim ◽  
Tae Kyong Kim ◽  
Sukha Yoo ◽  
Jin-Tae Kim
Keyword(s):  
Flow Rate ◽  
Room Temperature ◽  
In Vitro Study ◽  
High Flow ◽  
High Flow Rate ◽  
Low Flow ◽  
Fluid Temperature ◽  
Flow Rates ◽  
Fluid Warmer

Abstract Background A fluid warmer can prevent hypothermia during the perioperative period. This study evaluated the heating capabilities of Hotline and Barkey S-line under different flow rates and initial fluid temperatures, as well as after the extension line installation. Methods We measured the temperature of a 0.9% sodium chloride solution at the fluid warmer outlet (TProx) and the extension line end (TDistal) with three different initial fluid temperatures (room, warm, and cold) and two flow rates (250 ml/hr and 100 mL/hr). Results At a 250 ml/hr flow rate, the TProx and TDistal values were observed to be higher in Hotline than in S-line when using room-temperature or cold fluid. Administering of the warm fluid at the same flow rate significantly increased the TProx and TDistal values in S-line more than the cold and room-temperature fluids. At flow rates of 100 ml/hr, TDistal values were significantly lower than TProx values in both devices regardless of the initial fluid temperature. Conclusions Hotline outperformed S-line for warming fluids at a high flow rate with cold or room-temperature fluids. Administering warm fluid in S-line prevented a decrease in the fluid temperature at a high flow rate. However, at a low flow rate, the fluid temperature significantly decreased in both devices after passing through an extension line.

scholarly journals Influence of flow rate, fluid temperature, and extension line on Hotline and S-line heating capability: an in vitro study

2020 ◽  
Author(s):  
Hosu Kim ◽  
Tae Kyong Kim ◽  
Sukha Yoo ◽  
Jin-Tae Kim
Keyword(s):  
Flow Rate ◽  
Room Temperature ◽  
In Vitro Study ◽  
High Flow ◽  
High Flow Rate ◽  
Low Flow ◽  
Fluid Temperature ◽  
Flow Rates ◽  
Fluid Warmer

Abstract Background A fluid warmer can prevent hypothermia during the perioperative period. This study evaluated the heating capabilities of Hotline and Barkey S-line under different flow rates and initial fluid temperatures, as well as after the extension line installation. Methods We measured the temperature of a 0.9% sodium chloride solution at the fluid warmer outlet (TProx) and the extension line end (TDistal) with three different initial fluid temperatures (room, warm, and cold) and two flow rates (250 ml/hr and 100 mL/hr). Results At a 250 ml/hr flow rate, the TProx and TDistal values were observed to be higher in Hotline than in S-line when using room-temperature or cold fluid. Administering of the warm fluid at the same flow rate significantly increased the TProx and TDistal values in S-line more than the cold and room-temperature fluids. At flow rates of 100 ml/hr, TDistal values were significantly lower than TProx values in both devices regardless of the initial fluid temperature. Conclusions Hotline outperformed S-line for warming fluids at a high flow rate with cold or room-temperature fluids. Administering warm fluid in S-line prevented a decrease in the fluid temperature at a high flow rate. However, at a low flow rate, the fluid temperature significantly decreased in both devices after passing through an extension line.

Sign in / Sign up

Export Citation Format

Share Document