scholarly journals A FEW TESTS ON THE MOTION-THRESHOLD OF SOLID GRAINS UNDER AN OSCILLATORY FLUID MOTION

2011 ◽  
Vol 1 (5) ◽  
pp. 27
Author(s):  
Andre Martinot-Lagarde ◽  
Andre Fauquet
Keyword(s):  
Steady Flow ◽  
Fluid Motion ◽  
Motion Threshold

A few remarks are made about the similarity of the conditions for the initiation of motion of sand grains on a bed when these grains are acted upon by either a steady flow or by waves.

scholarly journals Forecasting yearly geomagnetic variation through sequential estimation of core flow and magnetic diffusion

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Maurits C. Metman ◽  
Ciarán D. Beggan ◽  
Philip W. Livermore ◽  
Jonathan E. Mound
Keyword(s):  
Magnetic Field ◽  
Steady Flow ◽  
Time Scales ◽  
Fluid Motion ◽  
Iron Alloy ◽  
Geomagnetic Variation ◽  
Magnetic Diffusion ◽  
The Core ◽  
Flux Approximation ◽  
The Magnetic Field

Abstract Earth’s internal magnetic field is generated through motion of the electrically conductive iron-alloy fluid comprising its outer core. Temporal variability of this magnetic field, termed secular variation (SV), results from two processes: one is the interaction between core fluid motion and the magnetic field, the other is magnetic diffusion. As diffusion is widely thought to take place over relatively long, millennial time scales, it is common to disregard it when considering yearly to decadal field changes; in this frozen-flux approximation, core fluid motion may be inferred on the core–mantle boundary (CMB) using observations of SV at Earth’s surface. Such flow models have been used to forecast variation in the magnetic field. However, recent work suggests that diffusion may also contribute significantly to SV on short time scales provided that the radial length scale of the magnetic field structure within the core is sufficiently short. In this work, we introduce a hybrid method to forecast field evolution that considers a model based on both a steady flow and diffusion, in which we adopt a two-step process: first fitting the SV to a steady flow, and then fitting the residual by magnetic diffusion. We assess this approach by hindcasting the evolution for 2010–2015, based on fitting the models to CHAOS-6 using time windows prior to 2010. We find that including diffusion yields a reduction of up to 25% in the global hindcast error at Earth’s surface; at the CMB this error reduction can be in excess of 77%. We show that fitting the model over the shortest window that we consider, 2009–2010, yields the lowest hindcast error. Based on our hindcast tests, we present a candidate model for the SV over 2020–2025 for IGRF-13, fit over the time window 2018.3–2019.3. Our forecasts indicate that over the next decade the axial dipole will continue to decay, reversed-flux patches will increase in both area and intensity, and the north magnetic (dip) pole will continue to migrate towards Siberia.

500 An in vitro steady flow model of mitral regurgitation by three-dimensional Doppler

1999 ◽  
Vol 1 ◽  
pp. S86-S86
Author(s):  
R DESIMONE ◽  
G GLOMBITZA ◽  
C VAHL ◽  
H MEINZER ◽  
S HAGL
Keyword(s):  
Mitral Regurgitation ◽  
Steady Flow ◽  
Flow Model ◽  
Three Dimensional

INFLUENCE OF HEAT TREATMENT OF MOUNTAIN MASSIVE ON TEMPERATURE MODE OF GEOTHERMAL CIRCULATION SYSTEM

2018 ◽  
pp. 44-50
Author(s):  
Yu. P. Morozov
Keyword(s):  
Heat Transfer ◽  
Operating Time ◽  
Fluid Motion ◽  
Coolant Temperature ◽  
Circulation System ◽  
Thermal Processes ◽  
Temperature Mode ◽  
Heat Influx ◽  
Stationary Heat Transfer

Based on the solution of the problem of non-stationary heat transfer during fluid motion in underground permeable layers, dependence was obtained to determine the operating time of the geothermal circulation system in the regime of constant and falling temperatures. It has been established that for a thickness of the layer H <4 m, the influence of heat influxes at = 0.99 and = 0.5 is practically the same, but for a thickness of the layer H> 5 m, the influence of heat inflows depends significantly on temperature. At a thickness of the permeable formation H> 20 m, the heat transfer at = 0.99 has virtually no effect on the thermal processes in the permeable formation, but at = 0.5 the heat influx, depending on the speed of movement, can be from 50 to 90%. Only at H> 50 m, the effect of heat influx significantly decreases and amounts, depending on the filtration rate, from 50 to 10%. The thermal effect of the rock mass with its thickness of more than 10 m, the distance between the discharge circuit and operation, as well as the speed of the coolant have almost no effect on the determination of the operating time of the GCS in constant temperature mode. During operation of the GCS at a dimensionless coolant temperature = 0.5, the velocity of the coolant is significant. With an increase in the speed of the coolant in two times, the error changes by 1.5 times.

CFD Investigation of Steady Flow in Bi-Leaflet Heart Valve Hinge

2000 ◽  
Vol 28 (1-2) ◽  
pp. 61-67 ◽  
Author(s):  
JunHong Wang ◽  
Tony Joon Hock Yeo ◽  
Chu-Sing Lim
Keyword(s):  
Steady Flow ◽  
Heart Valve

STEADY FLOW OF JOHNSON-SEGALMAN FLUID THROUGH POROUS MEDIUM OVER AN INCLINED PLATE

2019 ◽  
Vol 22 (5) ◽  
pp. 583-598
Author(s):  
Fawzia Mansour Elniel ◽  
Zainal Abdul Aziz ◽  
Arifah Bahar ◽  
Faisal Rasheed ◽  
Shaymaa Mustafa
Keyword(s):  
Porous Medium ◽  
Steady Flow ◽  
Inclined Plate
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