Hydraulic Resistance and Permeability in Human Lumbar Vertebral Bodies

2002 ◽  
Vol 124 (5) ◽  
pp. 533-537 ◽  
Author(s):  
Ruth S. Ochia ◽  
Randal P. Ching
Keyword(s):  
Fluid Flow ◽  
Hydraulic Resistance ◽  
High Speed ◽  
Lumbar Vertebrae ◽  
Pressure Flow ◽  
Flow Rates ◽  
Flow Through ◽  
Vertebral Bodies ◽  
The Mean ◽  
The Creation

Hydraulic resistance (HR) was measured for ten intact human lumbar vertebrae to further understand the mechanisms of fluid flow through porous bone. Oil was forced through the vertebral bodies under various volumetric flow rates and the resultant pressure was measured. The pressure-flow relationship for each specimen was linear. Therefore, HR was constant with a mean of 2.22±1.45kPa*sec/ml. The mean permeability of the intact vertebral bodies was 4.90×10−10±4.45×10−10m2. These results indicate that this methodology is valid for whole bone samples and enables the exploration of the effects of HR on the creation of high-speed fractures.

scholarly journals Percolation and Reynolds Flow in Elastic Contacts of Isotropic and Anisotropic, Randomly Rough Surfaces

2020 ◽  
Vol 69 (1) ◽  
Author(s):  
Anle Wang ◽  
Martin H. Müser
Keyword(s):  
Fluid Flow ◽  
Contact Area ◽  
Rough Surfaces ◽  
Flow Direction ◽  
Wave Length ◽  
System Size ◽  
Flow Through ◽  
The Mean ◽  
Randomly Rough Surfaces ◽  
Critical Contact

Abstract In this work, we numerically study the elastic contact between isotropic and anisotropic, rigid, randomly rough surfaces and linearly elastic counterfaces as well as the subsequent Reynolds flow through the gap between the two contacting solids. We find the percolation threshold to depend on the fluid flow direction when the Peklenik number indicates anisotropy unless the system size clearly exceeds the roll-off wave length parallel to the easy flow direction. A critical contact area near 0.415 is confirmed. Heuristically corrected effective-medium treatments satisfactorily provide Reynolds fluid flow conductances, e.g., for isotropic roughness, we identify accurate closed-form expressions, which only depend on the mean gap and the relative contact area. Graphic Abstract

Fluid flow through the hydraulic resistance with a dynamically variable geometry

2017 ◽  
Vol 12 (1) ◽  
pp. 59-66 ◽  
Author(s):  
I.Sh. Nasibullayev ◽  
E.Sh. Nasibullaeva
Keyword(s):  
Fluid Flow ◽  
Hydraulic Resistance ◽  
Flow Rate ◽  
Dynamic Change ◽  
Variable Geometry ◽  
Transverse Compression ◽  
Flat Channel ◽  
Channel Geometry ◽  
Flow Through ◽  
Through Hole

In this paper the fluid flow in a flat channel with a hydraulic resistance is studied for two cases of a dynamic change in the channel geometry: transverse compression of the opening of the hydraulic resistance (the flow is caused by a pressure drop applied to the layer) and longitudinal movement of the hydraulic resistance along the channel (the flow is caused by this movement). It is obtained that in a geometry with transverse compression the flow is laminar without the formation of vortices. In a geometry with longitudinal movement of the hydraulic resistance the flow rate of the liquid remains constant with the formation of stable vortices that move along the channel at the rate of motion of the hydraulic resistance. On the base of the modeling results an analytical model that takes into account the flow rate of the fluid from the width of the through hole of the resistance is constructed. This model contains four interpolation parameters and it can be used as an element of a computational stand for determining the generalized flow of liquid in the system under consideration.

Experimental Study of Gas-Liquid Flow Through a Multi-Stage, Mixed-Flow Electric Submersible Pump

2018 ◽  
Author(s):  
Marine Dupoiron
Keyword(s):  
High Speed ◽  
Imaging Techniques ◽  
Flow Patterns ◽  
Low Flow ◽  
Submersible Pump ◽  
Mixed Flow ◽  
Flow Rates ◽  
Flow Through ◽  
Inlet Conditions ◽  
Electric Submersible Pump

Laser Doppler velocimetry (LDV) and high-speed imaging techniques were used in a transparent model of a fourstage, mixed-flow commercial electric submersible pump (ESP) to characterize the flow through a range of inlet gas volume fractions (GVF) from 0 to 30%. Measurements demonstrate the presence high turbulence levels in the wake of the impeller blades, and recirculation cells at low flow rates. In gas-liquid conditions, the bubble size varied within a pump stage, as break-up occurred at the impeller tip, and coalescence was dominant in the diffuser, especially at low flow rates because of recirculation. At moderate-to-high inlet GVF, the first impeller acted as a mixer and the flow patterns at the stage level alternated between bubbly and radially separated flows, as short gas slugs propagated through the stages. The flow patterns at the stage level did not depend on the pump inclination, but the inlet conditions did, with worse performance induced by slugging flows for the horizontal setup.

Fluid-Induced Rotordynamic Instability in Rotary Atomizers

1989 ◽  
Vol 111 (2) ◽  
pp. 318-324
Author(s):  
J. Colding-Jorgensen
Keyword(s):  
Fluid Flow ◽  
Flow Rate ◽  
High Speed ◽  
Test Stand ◽  
Design Parameters ◽  
Rotordynamic Coefficients ◽  
Fluid Properties ◽  
Flow Through

A theory is presented for the calculation of rotordynamic coefficients for the fluid-rotor interaction in rotary atomizers, based on calculation of the fluid flow through a whirling atomizer wheel. The theory predicts potentially unstable rotor whirl in high-speed rotary atomizers. The whirl frequency can be that of the first critical forward or the first critical backward precession of the rotor, depending on atomizer wheel geometry, speed, fluid properties, and flow rate. The predicted whirl phenomena have been produced in an atomizer test stand. Both forward and backward precession have been observed to become unstable. The observed whirl directions and amplitudes are consistent with the calculated coefficients. Some design parameters are identified that can help control and suppress the whirl.

Simulation and Analysis of Rigid/Foil Electrolytic In-Process Dressing (ELID) Systems for Grinding

2004 ◽  
Vol 126 (3) ◽  
pp. 565-570 ◽  
Author(s):  
Zhenqi Zhu ◽  
Xiaohua Wang ◽  
Siva Thangam
Keyword(s):  
Fluid Flow ◽  
High Speed ◽  
Governing Equations ◽  
Supply Rate ◽  
Mean Velocity ◽  
Unidirectional Flow ◽  
High Speed Grinding ◽  
The Mean ◽  
Machine Systems ◽  
Good Agreement

The fluid flow problem in a traditional electrolytic in-process dressing (ELID) system is analyzed and solved numerically. The predicted mean velocity profiles in the dressing zone show flow patterns that are in good agreement with the mean velocity distributions for plane laminar/turbulent Couette flows observed in the experiments. The computational results reveal that insufficient electrolyte supply rate is the cause of the failure of the traditional ELID system for high-speed grinding. Results also show that to obtain effective high-speed ELID grinding, a consistent high inlet electrolyte velocity or supply rate is required. For the foil ELID system, governing equations describing the fluid flow in the dressing zone and the foil elastic deformation are formulated. Analytical solution based on unidirectional flow model for the problem is presented and effects of wheel surface speed and foil tension on the performance of the dressing system are discussed. It is shown that the foil ELID system has the potential to be effective for high-speed grinding with low electrolyte supply rates. The results will be useful to the development of new machine systems and processes for high-speed grinding.

Estimating the Coefficient of Inertial Resistance in Fluid Flow Through Porous Media

1974 ◽  
Vol 14 (05) ◽  
pp. 445-450 ◽  
Author(s):  
J. Geertsma
Keyword(s):  
Fluid Flow ◽  
Flow Resistance ◽  
Single Phase ◽  
Darcy’S Law ◽  
Darcy's Law ◽  
High Flow ◽  
Flow Through Porous Media ◽  
Flow Rates ◽  
Flow Through ◽  
Phase Fluid

Abstract The object of this paper is to introduce an empirical, time-honored relationship between inertia coefficient - frequently misnamed "turbulence factor" - permeability, and porosity, based on a combination of experimental data, dimensional analysis, and other physical considerations. The formula can be used effectively for, among other things, the preliminary evaluation of the number of wells in a new gas field and the spacing between them. Introduction It has long been recognized that Darcy's law for single-phase fluid flow through porous media,Equation 1 in which ?=superficial velocity µ=fluid viscosity k=formation permeability p=pressure head, is approximately correct only in a specific flow regime where the velocity ? is low. Single-phase fluid flow in reservoir rocks is often characterized by conditions in favor of this linearized flow law, but important exceptions do occur. They are in particular related to the surroundings of wells producing at high flow rates such as gas wells. For the prediction or analysis of the production behavior of such wells it is necessary to apply a more general nonlinear flow law. The appropriate formula was given in 1901 by Forchheimer1; it readsEquation 2 in which ?=density a=coefficient of viscous flow resistance 1/k ß=coefficient of inertial flow resistance. This equation indicates that in single-phase fluid flow through a porous medium two forces counteract the external force simultaneously - namely, viscous and inertial forces - the latter continuously gaining importance as the velocity ? increases. For low flow rates the viscous term dominates, whereas for high flow rates the inertia term does. The upper limit of practical applicability of Darcy's law can best be specified by some "critical value" orf the dimensionless ratio.Equation 3 which has a close resemblance to the Reynolds number. Observe that ß/a has the dimension of a length. Inertia and Turbulence As the Reynolds number is commonly used as an indicator for either laminar or turbulent flow conditions, the coefficient ß is often referred to as the turbulence coefficient. However, the phenomenon we are interested in has nothing to do with turbulence. The flow regime of concern is usually fully laminar. The observed departure from Darcy's law is the result of convective accelerations and decelerations of the fluid particles on their way through the pore space. Within the flow range normally experienced in oil and gas reservoirs, including the well's surroundings, energy losses caused by actual turbulence can be safely ignored.

Fluid Flow Through a Crack Network in Rocks

1983 ◽  
Vol 50 (4a) ◽  
pp. 707-711 ◽  
Author(s):  
R. Englman ◽  
Y. Gur ◽  
Z. Jaeger
Keyword(s):  
Fluid Flow ◽  
Gas Flow ◽  
Random Distribution ◽  
Crack Density ◽  
Two Dimensional ◽  
Threshold Density ◽  
Crack Network ◽  
Area Density ◽  
Flow Through ◽  
The Mean

A network of cracks pervading a rock is modeled by a random distribution of two-dimensional intersecting, complex, narrow cracks. The percolation properties of the resulting network are studied as functions of the crack-area density and size of the medium. Gas flow commences at a finite value of the crack density which in Arkansas Novaculite rocks amounts according to our model to 670 cracks per cm2. The mean probability of finding at least one crack intersecting another is 0.57 at the threshold density. Above that, the rock gas-flow permeability increases superlinearly with crack density due to the enhancement of short percolative paths.

A Computational Optimization of a Laminar Flow in a Small Tube With Fenestrations

2001 ◽  
Author(s):  
Iskender Sahin ◽  
Chris Hovland
Keyword(s):  
Fluid Flow ◽  
Small Diameter ◽  
Iterative Approach ◽  
Cfd Analysis ◽  
Numerical Parameter ◽  
Flow Rates ◽  
Computational Optimization ◽  
Small Tube ◽  
Flow Through ◽  
Small Discharge

Abstract An iterative approach by a CFD analysis was applied for optimizing the distribution of a laminar fluid flow through a small diameter tube with a closed end. The goal of the optimization was that flow rates through small discharge outlets (fenestrations) be close to uniform throughout the tube. Parameters used for the optimum design were: the pipe and fenestration hole diameters and the distribution of fenestration along the pipe, and the number of holes, among others. A numerical parameter describing the efficiency of each design was introduced and used for some comparisons.

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