Support Vector Regression and Computational Fluid Dynamics Modeling of Newtonian and Non-Newtonian Fluids in Annulus With Pipe Rotation

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Mehmet Sorgun ◽  
A. Murat Ozbayoglu ◽  
M. Evren Ozbayoglu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Gradient ◽  
Support Vector Regression ◽  
Newtonian Fluids ◽  
Support Vector ◽  
Pressure Losses ◽  
Percent Error ◽  
Pipe Rotation ◽  
Absolute Percent Error

The estimation of the pressure losses inside annulus during pipe rotation is one of the main concerns in various engineering professions. Pipe rotation is a considerable parameter affecting pressure losses in annulus during drilling. In this study, pressure losses of Newtonian and non-Newtonian fluids flowing through concentric horizontal annulus are predicted using computational fluid dynamics (CFD) and support vector regression (SVR). SVR and CFD results are compared with experimental data obtained from literature. The comparisons show that CFD model could predict frictional pressure gradient with an average absolute percent error less than 3.48% for Newtonian fluids and 19.5% for non-Newtonian fluids. SVR could predict frictional pressure gradient with an average absolute percent error less than 5.09% for Newtonian fluids and 5.98% for non-Newtonian fluids.

The Application of Non-Axisymmetric Endwall Contouring in a Single Stage, Rotating Turbine

2009 ◽  
Author(s):  
Glen Snedden ◽  
Dwain Dunn ◽  
Grant Ingram ◽  
David Gregory-Smith
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Gradient ◽  
Full Scale ◽  
Secondary Flows ◽  
Tip Clearance ◽  
Detailed Understanding ◽  
Low Speed ◽  
Endwall Contouring ◽  
Probe Measurements

As turbine manufacturers strive to develop machines that are more efficient, one area of focus has been the control of secondary flows. To a large extent these methods have been developed through the use of computational fluid dynamics and detailed measurements in linear and annular cascades and proven in full scale engine tests. This study utilises 5-hole probe measurements in a low speed, model turbine in conjunction with computational fluid dynamics to gain a more detailed understanding of the influence of a generic endwall design on the structure of secondary flows within the rotor. This work is aimed at understanding the influence of such endwalls on the structure of secondary flows in the presence of inlet skew, unsteadiness and rotational forces. Results indicate a 0.4% improvement in rotor efficiency as a result of the application of the generic non-axisymmetric endwall contouring. CFD results indicate a clear weakening of the cross passage pressure gradient, but there are also indications that custom endwalls could further improve the gains. Evidence of the influence of endwall contouring on tip clearance flows is also presented.

Abstract WP121: An Evaluation of Hemodynamics Across Intracranial Steno-occlusive Lesions by Computational Fluid Dynamics

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
Florence SY Fan ◽  
Vincent HL Ip ◽  
Alexander YL Lau ◽  
Anne YY Chan ◽  
Lisa WC Au ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Gradient ◽  
Pressure Difference ◽  
Pressure Ratio ◽  
Velocity Ratio ◽  
Strongly Correlated ◽  
Hemodynamic Parameters ◽  
Moderate Correlation ◽  
Anterior Circulation

Introduction: Intracranial atherosclerotic steno-occlusive disease (ICAS) is a major cause of stroke worldwide and portends a high risk of recurrence. Computational fluid dynamics (CFD) is a novel technique developed to solve and analyze the dynamic effects of fluid flow. We aimed to analyse hemodynamics across ICAS using CFD on processed CTA images and explore the correlation between the degree of arterial stenosis and hemodynamic flow status. Methods: We recruited patients with symptomatic ICAS from Acute Stroke Unit, Prince of Wales Hospital. All patients received CTA and DSA as vascular workup. Using CFD analysis of processed CTA images, we first defined the hemodynamic parameters, including pressure difference, pressure ratio, pressure gradient, shear strain rate ratio (SSR), wall shear stress (WSS) ratio and velocity ratio, across the stenosed vessels, and then we correlated the severity of stenosis as defined by DSA, with these parameters. Results: Among the 53 recruited patients (mean age 62.9 years, 69.8% males), 45 (85%) had lesions in the anterior circulation. The severity of stenosis showed a weak-to-moderate correlation with pressure difference (rs=0.392, p=0.004), pressure ratio (rs=-0.429, p=0.001) and pressure gradient (rs=0.419, p=0.002). There was no significant correlation between the severity of stenosis with SSR ratio, WSS ratio and velocity ratio. Among patients with anterior circulation stroke or TIA, the severity of stenosis showed a weak to moderate correlation with pressure difference (rs=0.381, p=0.01), pressure ratio (rs=-0.426, p=0.004) and pressure gradient (rs=0.407, p=0.005). For patients with posterior circulation stroke or TIA, the severity of stenosis was strongly correlated with pressure difference (rs=0.714, p=0.047) and pressure ratio (rs=-0.714, p=0.047); and very strongly correlated with velocity ratio (rs=0.833, p=0.01). Conclusions: The severity of ICAS showed only weak-to-moderate correlation with hemodynamic parameters across the culprit lesion. Thus, risk stratification and treatment based solely on stenotic severity may be inadequate. Our findings may guide further research in estimating stroke risks and selection of high-risk patients who may benefit from adjunctive treatments.

Simple Correlations and Analysis of Cuttings Transport With Newtonian and Non-Newtonian Fluids in Horizontal and Deviated Wells

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Mehmet Sorgun
Keyword(s):  
Pure Water ◽  
Newtonian Fluids ◽  
The Other ◽  
Cuttings Transport ◽  
Pressure Losses ◽  
Test Conditions ◽  
Bed Thickness ◽  
Solid Liquid ◽  
Cuttings Bed ◽  
Pipe Rotation

In this study, simple empirical frictional pressure losses and cuttings bed thickness correlations including pipe rotation are developed for solid-liquid flow in horizontal and deviated wellbores. Pipe rotation effects on cuttings transport in horizontal and highly inclined wells are investigated experimentally. Correlations are validated experimental data with pure water as well as four different non-Newtonian fluids for hole inclinations from horizontal to 60 degrees, flow velocities from 0.64 m/s to 3.56 m/s, rate of penetrations from 0.00127 to 0.0038 m/s, and pipe rotations from 0 to 250 rpm. Pressure drop within the test section, and stationary and/or moving bed thickness are recorded besides the other test conditions. The new correlations generated in this study are believed to be very practical and handy when they are used in the field.

Modeling of Newtonian Fluids in Annular Geometries With Inner Pipe Rotation

2010 ◽  
Author(s):  
Mehmet Sorgun ◽  
Jerome J. Schubert ◽  
Ismail Aydin ◽  
M. Evren Ozbayoglu
Keyword(s):  
Axial Velocity ◽  
Pressure Loss ◽  
Tangential Velocity ◽  
Flow Characteristics ◽  
Newtonian Fluids ◽  
Flow Loop ◽  
Eccentric Annulus ◽  
Pressure Losses ◽  
Proposed Model ◽  
Pipe Rotation

Flow in annular geometries, i.e., flow through the gap between two cylindrical pipes, occurs in many different engineering professions, such as petroleum engineering, chemical engineering, mechanical engineering, food engineering, etc. Analysis of the flow characteristics through annular geometries is more challenging when compared with circular pipes, not only due to the uneven stress distribution on the walls but also due to secondary flows and tangential velocity components, especially when the inner pipe is rotated. In this paper, a mathematical model for predicting flow characteristics of Newtonian fluids in concentric horizontal annulus with drill pipe rotation is proposed. A numerical solution including pipe rotation is developed for calculating frictional pressure loss in concentric annuli for laminar and turbulent regimes. Navier-Stokes equations for turbulent conditions are numerically solved using the finite differences technique to obtain velocity profiles and frictional pressure losses. To verify the proposed model, estimated frictional pressure losses are compared with experimental data which were available in the literature and gathered at Middle East Technical University, Petroleum & Natural Gas Engineering Flow Loop (METU-PETE Flow Loop) as well as Computational Fluid Dynamics (CFD) software. The proposed model predicts frictional pressure losses with an error less than ± 10% in most cases, more accurately than the CFD software models depending on the flow conditions. Also, pipe rotation effects on frictional pressure loss and tangential velocity is investigated using CFD simulations for concentric and fully eccentric annulus. It has been observed that pipe rotation has no noticeable effects on frictional pressure loss for concentric annuli, but it significantly increases frictional pressure losses in an eccentric annulus, especially at low flow rates. For concentric annulus, pipe rotation improves the tangential velocity component, which does not depend on axial velocity. It is also noticed that, as the pipe rotation and axial velocity are increased, tangential velocity drastically increases for an eccentric annulus. The proposed model and the critical analysis conducted on velocity components and stress distributions make it possible to understand the concept of hydro transport and hole cleaning in field applications.

Using computational fluid dynamics to evaluate a novel venous cannula (Smart canula ®) for use in cardiopulmonary bypass operating procedures

Perfusion ◽  
2007 ◽  
Vol 22 (4) ◽  
pp. 257-265 ◽  
Author(s):  
D. Jegger ◽  
S. Sundaram ◽  
K. Shah ◽  
I. Mallabiabarrena ◽  
G. Mucciolo ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cardiopulmonary Bypass ◽  
Pressure Gradient ◽  
Surface Area ◽  
Mass Flow ◽  
Stokes Equations ◽  
Venous Drainage ◽  
Dimensional System ◽  
Flow Rates

Peripheral access cardiopulmonary bypass (CPB) is initiated with percutaneous cannulae (CTRL) and venous drainage is often impeded due to smaller vessel and cannula size. A new cannula (Smartcanula ®, SC) was developed which can change shape in situ and, therefore, may improve venous drainage. Its performance was evaluated using a 2-D computational fluid dynamics (CFD) model. The Navier-Stokes equations could be simplified due to the fact that we use a steady state and a 2-dimensional system while the equation of continuity (ρ constant) was also simplified. We compared the results of the SC to the CTRL using CFDRC® (Version 6.6, CFDRC research corporation, Huntsville, USA) at two preloads (300 and 700 Pa). The SC's mass flow rate outperformed the CTRL by 12.1% and 12.2% at a pressures of 300 and 700 Pa, respectively. At 700 Pa, a pressure gradient of 50% was measured for the CTRL and 11% for the SC. The mean velocity at the 700 Pa for the CTRL was 1.0 m.s-1 at exit while the SC showed an exit velocity of 1.3 m.s-1. Shear rates inside the cannulae were similar between the two cannulae. In conclusion, the prototype shows greater mass flow rates compared to the classic cannula; thus, it is more efficient. This is also advocated by a better pressure gradient and higher average velocities. By reducing cannula-tip surface area or increasing hole surface area, greater flow rates are achieved. Perfusion (2007) 22, 257—265.

scholarly journals Electrokinetically Forced Turbulence in Microfluidic Flow

2018 ◽  
Author(s):  
Willy L. Duffle ◽  
Evan C. Lemley
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Newtonian Fluids ◽  
Rectangular Microchannel ◽  
Electromagnetic Simulations ◽  
Microfluidic Flow ◽  
Low Reynolds ◽  
Forced Turbulence

While laminar flow heat transfer and mixing in microfluidic geometries has been investigated experimentally, as has the effect of geometry-induced turbulence in microfluidic flow (it is well documented that turbulence increases convective heat transfer in macrofluidic flow), little literature exists investigating the effect of electrokinetically-induced turbulence on heat transfer at the micro scale. Using recently observed experimental data, this work employed computational fluid dynamics coupled with electromagnetic simulations to determine if electrokinetically-forced, low-Reynolds number turbulence could be observed in a rectangular microchannel with using Newtonian fluids. Analysis of the results was done via comparison to the experimental criteria defined for turbulent flow. This work shows that, even with a simplified simulation setup, computational fluid dynamics (CFD) software can produce results comparable to experimental observations of low-Reynolds turbulence in microchannels using Newtonian fluids. In addition to comparing simulated velocities and turbulent energies to experimental data this work also presents initial data on the effects of electrokinetic forcing on microfluidic flow based on entropy generation rates.

Influence of Pipe Rotation and Reciprocation in Flow of Non-Newtonian Fluids in Eccentric Annular Spaces

2006 ◽  
Author(s):  
David J. Lugo ◽  
Armando J. Blanco
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Shear Stress ◽  
Power Law ◽  
Rotation Speed ◽  
Oil Industry ◽  
Annular Space ◽  
Bingham Plastic ◽  
Static Fluid ◽  
Pipe Rotation

Some industrials processes are associated with flow of non-Newtonian fluids in annular spaces created between parallel pipes. Examples are found in oil industry and food industrial processing. Depending on relative position of both axes, a concentric or eccentric annular space is created. In some typical applications the fluid rheology non-Newtonian and models such as Bingham Plastic or Power Law are required for adequate representation of internal deformations of fluid elements when shear stresses are applied. Depending on annulus eccentricity high resistance can be opposed to flow on narrowest section, including the possibility of having static or quasi-static fluid close to the internal annulus walls. In order to remove this static fluid, two different operations are usually proposed: pipe rotation and pipe reciprocation. In this way, less mobile fluid can be put in motion increasing shear stress. These operations are justified by experimental evidence exists. Scale experiments have been done and predictions for flow behavior in large facilities are extrapolated. However, in large facilities, as oil wells are highly pressurized and they are very deep, it is almost impossible to verify if the whole fluid is mobile and no by-pass fluid remains in the narrowest section of annular space. So, Computational Fluid Dynamics constitutes an ideal technique for analyzing this kind of problem. In this paper, though a Computational Fluid Dynamics study we aim to evaluate the efficiency of pipe rotation and pipe reciprocation in static or quasi-static fluids for Bingham Plastic or Power Law fluid. In order to consider realistic scenarios, oil industry typical conditions are considered for fluid density, rheological parameters, flow rates, casing and hole sizes, and annulus eccentricity. The influence of the variables eccentricity and rotation speed, and the use of reciprocation in shear stress at walls, were used as a measure to evaluate efficiency in static fluid removal. The flow regime was considered laminar. Numerical model capability to reproduce accurately flow patterns in these conditions was assured by comparing it with others analytical-numerical solutions for concentric systems. Results show that both operations are effective for helping in static fluid remotion. However, notable increment for efficiency is observed for eccentricities below 60%. In particular, pipe rotation is effective when rotation speed is greater than 20 RPM for eccentricity greater than 40%. Below this limit, pipe reciprocation is more effective than pipe rotation, independently of the rheological model used to represent the fluid.

scholarly journals Experimental and CFD studies on determination of injection and production wells location considering reservoir heterogeneity and capillary number

2019 ◽  
Vol 74 ◽  
pp. 4 ◽  
Author(s):  
Pouyan Ahmadi ◽  
Ehsan Ghandi ◽  
Masoud Riazi ◽  
Mohammad Reza Malayeri
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Gradient ◽  
Capillary Number ◽  
Recovery Factor ◽  
Injection Wells ◽  
Flow Rates ◽  
Reservoir Heterogeneity ◽  
Production Wells ◽  
Gradient Line

The in-depth knowledge of reservoir heterogeneity is imperative for identifying the location of production and injection wells. The present study aimed at experimentally investigating the process of water flooding in the viscous oil-saturated glass micromodels, which contain layers with different permeability where the fractures were placed in different locations. Computational Fluid Dynamics (CFD) simulations of flooding were also conducted to study the impact of different water flow rates and wettability states. The results showed that the fractures, which have a deviation with the trend of maximum pressure gradient line, would widen the water path and vice versa. The performance of injection wells would increase the recovery factor by 18% if these would be located in the zones with high permeability for low flow rates of water. With changes in wettability state from water to oil wet conditions, the oil production will increase by 11%. Computational Fluid Dynamics results also indicated that an increase in the capillary number from 0.8 × 10−6 to 1.6 × 10−5, would cause the recovery factor to decrease as much as 14.34% while further increase from 1.6 × 10−5 to 2.24 × 10−5, the oil production will increase by 9.5%. Comparison between the obtained oil recoveries indicates that the maximum oil recoveries will happen when the injector well is located in the zone where ascending permeability, capillary number greater than 4.81 × 10−6 and also fracture with the most deviation with pressure gradient line (i.e. angular pattern) are gathered in an area between the injection and production wells.

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