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Inertia Controlled Capillary Pressure at the Juncture between Converging and Uniform Channels.

ABSTRACT: In this research, we reveal the transient behavior of capillary pressure as the fluid-fluid interface travels across the juncture between a converging and uniform capillary, via high-resolution CFD (Computational Fluid Dynamics) simulations. Simulations were performed at different wetting conditions (strong-wet and intermediate-wet) and capillary wall convergence angles. Our results demonstrate that as the angle of convergence increases, capillary pressure at the junction decreases commensurately. Moreover, in contrast to strong-wet conditions, the profile of capillary pressure at the converging-uniform capillary juncture under intermediate-wet conditions is highly non-monotonic, being characterized by a parabola-like form. This non-monotonic behavior is a manifestation of strong inertial forces governing dynamic fluid-fluid interface morphology. This yields conditions that promote the advancement of the fluid-fluid interface, as inertial forces partially nullify the capillary pressure required for the immiscible interface to enter the uniform capillary. In addition to numerical analysis detailed above, a novel theoretical stability criteria that is capable of distinguishing between stable (capillary dominated) and unstable (inertia dominated) interfacial regimes at the converging-uniform capillary juncture is also proposed. In summary, this fundamental study offers new insights into the interface invasion protocol, and paves the way for the re-evaluation of capillary junction controlled interfacial dynamics.

SUBMITTER: Rabbani HS

PROVIDER: S-EPMC6761262 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Inertia Controlled Capillary Pressure at the Juncture between Converging and Uniform Channels.

Rabbani Harris Sajjad HS Seers Thomas Daniel TD

Scientific reports 20190925 1

In this research, we reveal the transient behavior of capillary pressure as the fluid-fluid interface travels across the juncture between a converging and uniform capillary, via high-resolution CFD (Computational Fluid Dynamics) simulations. Simulations were performed at different wetting conditions (strong-wet and intermediate-wet) and capillary wall convergence angles. Our results demonstrate that as the angle of convergence increases, capillary pressure at the junction decreases commensuratel ...[more]

PMID: 31554836

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Project description:BackgroundOnly approximately half of patients with hypertension have their blood pressure controlled, due in large part to the tendency of primary care providers (PCPs) not to intensify treatment when blood pressure values are elevated.ObjectiveThis study tested the effect of an intervention designed to help patients ask questions at the point of care to encourage PCPs to appropriately intensify blood pressure treatment.MethodsPCPs and their patients with hypertension (N=500) were recruited by letter and randomized into 2 study groups: (1) intervention condition in which patients used a fully automated website each month to receive tailored messages suggesting questions to ask their PCP to improve blood pressure control, and (2) control condition in which a similar tool suggested questions to ask about preventive services (eg, cancer screening). The Web-based tool was designed to be used during each of the 12 study months and before scheduled visits with PCPs. The primary outcome was the percentage of patients in both conditions with controlled blood pressure.ResultsOf 500 enrolled patients (intervention condition: n=282; control condition: n=218), 418 (83.6%) completed the 12-month follow-up visit. At baseline, 289 (61.5%) of participants had controlled blood pressure. Most (411/500, 82.2%) participants used the intervention during at least 6 of 12 months and 222 (62.5%) reported asking questions directly from the Web-based tool. There were no group differences in asking about medication intensification and there were no differences in blood pressure control after 12 months between the intervention condition (201/282, 71.3%) and control condition (143/218, 65.6%; P=.27) groups. More intervention condition participants discussed having a creatinine test (92, 52.6% vs 49, 35.5%; P=.02) and urine protein test (81, 44.8% vs 21, 14.6%; P<.001), but no group differences were observed in the rate of testing. The control condition participants reported more frequent discussions about tetanus and pneumonia vaccines and reported more tetanus (30, 13.8% vs 15, 5.3%; P=.02) and pneumonia (25, 11.5% vs 16, 5.7%; P=.02) vaccinations after 12 months.ConclusionsThe use of an interactive website designed to overcome clinical inertia for hypertension care did not lead to improvements in blood pressure control. Participant adherence to the intervention was high. The control intervention led to positive changes in the use of preventive services (eg, tetanus immunization) and the intervention condition led to more discussions of hypertension-relevant tests (eg, serum creatinine and urine protein). By providing patients with individually tailored questions to ask during PCP visits, this study demonstrated that participants were likely to discuss the questions with PCPs. These discussions did not, however, lead to improvements in blood pressure control.Trial registrationClinicalTrials.gov NCT00377208; http://clinicaltrials.gov/ct2/show/NCT00377208 (Archived by WebCite at http://www.webcitation.org/6IqWiPLon).

Project description:Right ventricular failure from increased pulmonary vascular loading is a major cause of morbidity and mortality, yet its modulation by disease remains poorly understood. We tested the hypotheses that, unlike the systemic circulation, pulmonary vascular resistance (R(PA)) and compliance (C(PA)) are consistently and inversely related regardless of age, pulmonary hypertension, or interstitial fibrosis and that this relation may be changed by elevated pulmonary capillary wedge pressure, augmenting right ventricular pulsatile load.Several large clinical databases with right heart/pulmonary catheterization data were analyzed to determine the R(PA)-C(PA) relationship with pulmonary hypertension, pulmonary fibrosis, patient age, and varying pulmonary capillary wedge pressure. Patients with suspected or documented pulmonary hypertension (n=1009) and normal pulmonary capillary wedge pressure displayed a consistent R(PA)-C(PA) hyperbolic (inverse) dependence, C(PA)=0.564/(0.047+R(PA)), with a near-constant resistance-compliance product (0.48±0.17 seconds). In the same patients, the systemic resistance-compliance product was highly variable. Severe pulmonary fibrosis (n=89) did not change the R(PA)-C(PA) relation. Increasing patient age led to a very small but statistically significant change in the relation. However, elevation of the pulmonary capillary wedge pressure (n=8142) had a larger impact, significantly lowering C(PA) for any R(PA) and negatively correlating with the resistance-compliance product (P<0.0001).Pulmonary hypertension and pulmonary fibrosis do not significantly change the hyperbolic dependence between R(PA) and C(PA), and patient age has only minimal effects. This fixed relationship helps explain the difficulty of reducing total right ventricular afterload by therapies that have a modest impact on mean R(PA). Higher pulmonary capillary wedge pressure appears to enhance net right ventricular afterload by elevating pulsatile, relative to resistive, load and may contribute to right ventricular dysfunction.

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Inertia Controlled Capillary Pressure at the Juncture between Converging and Uniform Channels.

Publications

Inertia Controlled Capillary Pressure at the Juncture between Converging and Uniform Channels.

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