Rheology of Polymer Melts—A Correlation of Dynamic and Steady Flow Measurements

2009 ◽  
pp. 178-178-11 ◽  
Author(s):  
W. P. Cox ◽  
E. H. Merz
Keyword(s):  
Steady Flow ◽  
Polymer Melts ◽  
Flow Measurements

Flow Measurements in a Human Femoral Artery Model With Reverse Lumen Curvature

1988 ◽  
Vol 110 (4) ◽  
pp. 300-309 ◽  
Author(s):  
L. H. Back ◽  
M. R. Back ◽  
E. Y. Kwack ◽  
D. W. Crawford
Keyword(s):  
Steady Flow ◽  
Femoral Artery ◽  
Flow Simulation ◽  
Reynolds Numbers ◽  
Secondary Flows ◽  
Reverse Direction ◽  
Flow Measurements ◽  
Left Femoral Artery ◽  
Lesion Localization ◽  
Made In

Flow visualization and wall pressure measurements were made in a smooth reverse curvature model that conformed to the gentle “s” shape of a left femoral artery angiogram of a patient in a clinical trial. Observed lesion localization at the inner (lesser) curvatures appeared to be associated with secondary flows in the wall vicinity directed toward the inner curvatures that tended to reverse direction in the flow entering the reverse curvature region. Moderate flow resistance increases of about 20 percent above the Poiseuille flow relation were found at the higher physiological Reynolds numbers Re above about 600–700 and thus Dean numbers for steady flow. For pulsatile flow simulation, flow resistances did not increase up to the largest Re of 470 tested. Apparently, the large variations in velocity during the cardiac cycle disrupted the stronger secondary flow patterns observed at the higher Reynolds numbers for steady flow.

scholarly journals Measuring pulmonary arterial compliance: mission impossible? Insights from a novel in vivo continuous-flow based experimental model

2018 ◽  
Vol 8 (2) ◽  
pp. 204589401877688 ◽  
Author(s):  
Frédéric Vanden Eynden ◽  
Thierry Bové ◽  
Marie-Luce Chirade ◽  
Guido Van Nooten ◽  
Patrick Segers
Keyword(s):  
Steady Flow ◽  
Pulse Pressure ◽  
Pulsatile Flow ◽  
Pulmonary Circulation ◽  
Continuous Flow ◽  
Arterial Compliance ◽  
Exponential Fitting ◽  
Flow Conditions ◽  
Flow Measurements ◽  
Pulmonary Arterial

Arterial compliance (C) is related to the elasticity, size, and geometrical distribution of arteries. Compliance is a determinant of the load that impedes ventricular ejection. Measuring compliance is difficult, particularly in the pulmonary circulation in which resistive and compliant vessels overlap. Comparing different methods for quantification of compliance to a method that involves a continuous flow might help to identify the optimal method. Pulmonary arterial compliance was computed in six pigs based on the stroke volume to pulse pressure ratio, diastolic decay exponential fitting, area method, and the pulse pressure method (PPM). Compliance measurements were compared to those obtained under continuous flow conditions through a right ventricular bypass (Heartware Inc., Miami Lakes, FL, USA). Compliance was computed for various flows using diastolic decay exponential fitting after an abrupt interruption of the pump. Under the continuous flow conditions, resistance (R) was a decreasing function of the flow, and the fitting to P = e-t/RC yielded a pulmonary time constant (RC) of 2.06 s ( ± 0.48). Compliance was an increasing function of flow. Steady flow inter-method comparisons of compliance under pulsatile flow conditions showed large discrepancies and values (7.23 ± 4.47 mL/mmHg) which were lower than those obtained under continuous flow conditions (10.19 ± 1 0.31 mL/mmHg). Best agreement with steady flow measurements is obtained with the diastolic decay method. Resistance and compliance are both flow-dependent and are inversely related in the pulmonary circulation. The dynamic nature of the pulsatile flow may induce a non-uniformly distributed compliance, with an influence on the methods of measurement.

The steady flow shear modulus of polymer melts

1966 ◽  
Vol 10 (1) ◽  
pp. 75-80 ◽  
Author(s):  
L. L. Blyler ◽  
T. W. Huseby
Keyword(s):  
Shear Modulus ◽  
Steady Flow ◽  
Polymer Melts ◽  
Flow Shear

Steady Flow and Dynamic Oscillatory Experiments on Polymer Melts

1967 ◽  
Vol 11 (1) ◽  
pp. 77-94 ◽  
Author(s):  
T. W. Huseby ◽  
L. L. Blyler
Keyword(s):  
Steady Flow ◽  
Polymer Melts

Non-Steady Flow Measurements Inside a Hydrodynamic Torque Converter by Hot-Film Anemometry

1992 ◽  
Author(s):  
V. Browarzik ◽  
K. G. Grahl
Keyword(s):  
Flow Field ◽  
Steady Flow ◽  
Torque Converter ◽  
Operating Conditions ◽  
Measuring System ◽  
Pump Impeller ◽  
Flow Measurements ◽  
First Results ◽  
Hot Film ◽  
Hot Film Anemometry

The overall-characteristics of hydrodynamic torque converters have been discussed often, although there is little knowledge about the flow field inside the circuit. During former investigations at our institute flow measurements have been made and a CFD-program was developed to calculate the flow through the guide vanes and the pump impeller. Our present studies now examine the non-steady flow field at the inlet and outlet of the pump and the turbine impeller by means of hot-film anemometry and a computer based measuring system. The measuring techniques have been developed and now measurements are made at different operating points. Later the measurements will be performed with special regard to non-steady changes of operating conditions. The paper describes the test facilities, the measuring equipment and the techniques used to evaluate the measured data. First results of test measurements are presented.

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