This paper focuses on the effect of geometrical cross section between rectangular and circular shapes on the hydrodynamic focusing of a micro flow cytometer device. The effect of fluid flow ratio between the main and sheath channels on the focusing width is studied. This study has been performed using a COMSOL Multiphysics simulation tool. The results showed that focusing width decreases as the ratio between main channel and sheath channels are increased. The concentration at long-range is studied and indicated that circular shape can sustain a higher concentration at the centre along the channel compared with rectangular shape. The velocity at the cross-section of the channel-junction shows that circular shape produces higher velocity at the centre of the channel compare to that of the rectangular shape. The effect of flow ratio and geometrical shape are significantly vital for microfluidic system which utilizes hydrodynamic focusing for biological and chemical analysis. From the result, micro flow cytometer studied able to use for human body cells such as glucose, virus, red blood cells and white blood cells which have a range size of 2-120 microns.
Mesoscopic simulation of incompressible fluid flow in porous mediaeSAT Journals
Abstract
Lattice Boltzmann method is used to simulate cavity driven fluid flow in porous media. A square cavity is considered with the top
lid moving with uniform velocity and other sides kept stationary. Simulation is carried out for values of Darcy number ranging
from 10-6 to10-2 at Reynolds number 10 and 100. Influence of Darcy number and Reynolds number is investigated on velocity
profiles and the streamline plots. Half-way bounce back boundary conditions are employed in the numerical simulation. The
numerical code is first verified with the results available in the literature and then used to simulate the Newtonian fluid flow in
porous media. The Darcy number and the Reynolds number were observed to have great influence on the flow properties and the
location of the primary vortex. Simulation was carried out for a 100100 mesh grid and a fine agreement is established theories
in incompressible fluid flow.
Keywords: Lattice Boltzmann method, incompressible flow, porous media
Effect of Petrophysical Parameters on Water Saturation in Carbonate FormationIJERA Editor
Assessment of petrophysical parameters is very essential for reservoir engineers. Three techniques can be used to
predict reservoir properties: well logging, well testing, and core analysis. Cementation factors and saturation
exponents are crucial for calculation, and their values pose a pronounced effect on water saturation estimation. In
this study, a sensitivity analysis was performed to investigate the influence of cementation factor and saturation
exponent variation, as it applies to logs and core analysis, for use in water saturation estimates. Measurements of
water saturation resulting from these variations showed a maximum spread difference of around fifteen percent.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Design and simulation of microfluidic passive mixer with geometric variationeSAT Journals
Abstract
Microfluidic designs are advantageous and are extensively used in number of fields related to biomedical and biochemical
engineering. The objective of this paper is to perform numerical simulations to optimize the design of microfluidic mixers in order
to achieve optimum mixing. In the present study, fluid mixing in different type of micro channels has been investigated. Numerical
simulations are performed in order to understand the effect of channel geometry parameters on mixing performance. A two
dimensional “T shaped” passive microfluidic mixer is restructured by employing the rectangular shaped obstacles in the channel
to improve the mixing performance. The impact of proper placement of obstacles in the channel is demonstrated by applying the
leakage concept. It has been observed that, the channel design with non-leaky obstacles (i.e. without leaky barriers) has presented
better mixing performance in contrast to channel design with leaky obstacles (i.e. leaky barriers) and channel design without
obstacles. The mixing occurs by virtue of secondary flow and generation of vortices due to curling of fluids in the channel on
account of the presence of obstacles. This passive mixer has achieved complete mixing of fluids in few seconds or some
milliseconds, which is certainly acceptable to utilize in biological applications such as cell dynamics, drug screening,
toxicological screening and others.
Keywords: Microfluidic Mixing, Passive Mixer, Microchannel, Numerical Simulation
This paper focuses on the effect of geometrical cross section between rectangular and circular shapes on the hydrodynamic focusing of a micro flow cytometer device. The effect of fluid flow ratio between the main and sheath channels on the focusing width is studied. This study has been performed using a COMSOL Multiphysics simulation tool. The results showed that focusing width decreases as the ratio between main channel and sheath channels are increased. The concentration at long-range is studied and indicated that circular shape can sustain a higher concentration at the centre along the channel compared with rectangular shape. The velocity at the cross-section of the channel-junction shows that circular shape produces higher velocity at the centre of the channel compare to that of the rectangular shape. The effect of flow ratio and geometrical shape are significantly vital for microfluidic system which utilizes hydrodynamic focusing for biological and chemical analysis. From the result, micro flow cytometer studied able to use for human body cells such as glucose, virus, red blood cells and white blood cells which have a range size of 2-120 microns.
Mesoscopic simulation of incompressible fluid flow in porous mediaeSAT Journals
Abstract
Lattice Boltzmann method is used to simulate cavity driven fluid flow in porous media. A square cavity is considered with the top
lid moving with uniform velocity and other sides kept stationary. Simulation is carried out for values of Darcy number ranging
from 10-6 to10-2 at Reynolds number 10 and 100. Influence of Darcy number and Reynolds number is investigated on velocity
profiles and the streamline plots. Half-way bounce back boundary conditions are employed in the numerical simulation. The
numerical code is first verified with the results available in the literature and then used to simulate the Newtonian fluid flow in
porous media. The Darcy number and the Reynolds number were observed to have great influence on the flow properties and the
location of the primary vortex. Simulation was carried out for a 100100 mesh grid and a fine agreement is established theories
in incompressible fluid flow.
Keywords: Lattice Boltzmann method, incompressible flow, porous media
Effect of Petrophysical Parameters on Water Saturation in Carbonate FormationIJERA Editor
Assessment of petrophysical parameters is very essential for reservoir engineers. Three techniques can be used to
predict reservoir properties: well logging, well testing, and core analysis. Cementation factors and saturation
exponents are crucial for calculation, and their values pose a pronounced effect on water saturation estimation. In
this study, a sensitivity analysis was performed to investigate the influence of cementation factor and saturation
exponent variation, as it applies to logs and core analysis, for use in water saturation estimates. Measurements of
water saturation resulting from these variations showed a maximum spread difference of around fifteen percent.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Design and simulation of microfluidic passive mixer with geometric variationeSAT Journals
Abstract
Microfluidic designs are advantageous and are extensively used in number of fields related to biomedical and biochemical
engineering. The objective of this paper is to perform numerical simulations to optimize the design of microfluidic mixers in order
to achieve optimum mixing. In the present study, fluid mixing in different type of micro channels has been investigated. Numerical
simulations are performed in order to understand the effect of channel geometry parameters on mixing performance. A two
dimensional “T shaped” passive microfluidic mixer is restructured by employing the rectangular shaped obstacles in the channel
to improve the mixing performance. The impact of proper placement of obstacles in the channel is demonstrated by applying the
leakage concept. It has been observed that, the channel design with non-leaky obstacles (i.e. without leaky barriers) has presented
better mixing performance in contrast to channel design with leaky obstacles (i.e. leaky barriers) and channel design without
obstacles. The mixing occurs by virtue of secondary flow and generation of vortices due to curling of fluids in the channel on
account of the presence of obstacles. This passive mixer has achieved complete mixing of fluids in few seconds or some
milliseconds, which is certainly acceptable to utilize in biological applications such as cell dynamics, drug screening,
toxicological screening and others.
Keywords: Microfluidic Mixing, Passive Mixer, Microchannel, Numerical Simulation
The paper presents a fundamental study of the polymer flow within a “wave” type screw channel. The analysis is performed on an “unwrapped” form of a conventional screw channel and a “wave” type channel of similar size. A 3D Finite Element Method
(FEM) simulation was used to simulate the flow field and flow characteristics of the wave channel are compared relative to the plain channel.
An artificial intelligence based improved classification of two-phase flow patte...ISA Interchange
Flow pattern recognition is necessary to select design equations for finding operating details of the process and to perform computational simulations. Visual image processing can be used to automate the interpretation of patterns in two-phase flow. In this paper, an attempt has been made to improve the classification accuracy of the flow pattern of gas/ liquid two- phase flow using fuzzy logic and Support Vector Machine (SVM) with Principal Component Analysis (PCA). The videos of six different types of flow patterns namely, annular flow, bubble flow, churn flow, plug flow, slug flow and stratified flow are re- corded for a period and converted to 2D images for processing. The textural and shape features extracted using image processing are applied as inputs to various classification schemes namely fuzzy logic, SVM and SVM with PCA in order to identify the type of flow pattern. The results obtained are compared and it is observed that SVM with features reduced using PCA gives the better classification accuracy and computationally less intensive than other two existing schemes. This study results cover industrial application needs including oil and gas and any other gas-liquid two-phase flows.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
On Similarity of Differential Capacity and Capillary Pressure FractalKhalid Al-Khidir
On Similarity of Differential Capacity and Capillary Pressure Fractal Dimensions for Characterizing Shajara Reservoirs of the Permo-Carboniferous Shajara Formation, Saudi Arabia
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Modelling study of jet metal interaction in ld processeSAT Journals
Abstract Water model experiments have been carried out in a 1/30th scaled down model of the 100 ton LD converter in order to investigate the effect of changing the lance height and the gas flow rate on the penetration depth of liquid with different exit diameters. It is found the penetration depth increases with decreasing nozzle diameter, decreasing the lance height and with increase the gas flow rate. Gas jets impinging onto a gas–liquid interface of a liquid pool are also studied using computational fluid dynamics modeling, which aims to obtain a better understanding of the behavior of the gas jets. The gas and liquid flows are modeled using the volume of fluid technique. The governing equations in the axisymmetric cylindrical coordinates are solved by the CFD simulation using FLUENT. The computed results are compared with experimental result and it isfound a good match with all the data. Keywords: LD process, Water Modeling, Penetration Depth, Volume of Fluid, CFD.
On Modeling Water Transport in Polymer Electrolyte Membrane Fuel Cell_Crimson...Crimson_Biostatistics
On Modeling Water Transport in Polymer Electrolyte Membrane Fuel Cell by Ahmed Kaffel* in OABB
There is a great need to predict liquid water saturation in porous layers such as gas diffusion layers (GDL) and micro porous layers (MPL) of polymer electrolyte membrane fuel cells (PEMFCs) as this is a key parameter in flooding occurrence which is a limiting factor of PEM fuel cell performance. Several models have been developed in order to study water distribution and migration in micro porous layers. These models require heavy computational efforts and doubt in their applicability to the gas diffusion layer (GDL). Recently Qin & Hassanizadeh [1] developed a new approach based on the reduced continua model for modeling multiphase flow through a stack of thin porous layers.
For more open access journals in Crimson Publishers please click on link: https://crimsonpublishers.com/
For more articles in open access Biostatistics journals please click on link: https://crimsonpublishers.com/oabb/
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Evaluation of Morphometric Parameters Derived from CartoDEM and Aster GDEM wi...Dr Ramesh Dikpal
From three different sources viz. survey of India topographic map (1:50,000), CartoDEM (10 mts) and Aster GDEM (30 mts) morphometric parameters are derived and evaluated. Manually digitized the drainage network from toposheets and extracted drainage network system from CartoDEM and Aster GDEM using ArcGIS 10.2 software. Basic, derived and shape parameters are considered for basin analysis. The mean bifurcation ratio of the given basin for CartoDEM & Aster GDEM are having nearby values and also indicates some sort of geological control, high stream frequency (Fs) is indicative of high relief and low infiltration capacity of the bedrock pointing towards the increase in stream population with respect to increase in drainage density, low drainage density (Dd) leads to coarse drainage texture, value of Lg for topographic, CartoDEM and Aster GDEM data indicating very fine texture & fine texture respectively. From the shape parameters the Kumudvathi watershed indicates it is sub-circular and elongated. The results from the high resolution data will have the nearby values and less of % variation, whereas in low resolution data % of variation is more and will not meet criteria.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The effect of rotational speed variation on the velocity vectors in the singl...IOSR Journals
The current investigation is aimed to simulate the three-dimensional complex internal flow in a
centrifugal pump impeller with five twisted blades by using a specialized computational fluid dynamics (CFD)
software ANSYS /FLUENT 14code with a standard k-ε two-equation turbulence model.
A single blade passage will be modeled to give more accurate results for velocity vectors on (blade, hub, and
shroud). The potential consequences of velocity vectors associated with operating a centrifugal compressor in
variable rotation speed.
A numerical three-dimensional, through flow calculations to predict velocity vectors through a
centrifugal pump were presented to examined the effect of rotational speed variation on the velocity vectors of
the centrifugal pump . The contours of the velocity vectors of the blade, hub, and shroud indicates low velocity
vectors in the suction side at high rotational speed (over operation limits )and the velocity vectors increases
gradually until reach maximum value at the leading edge (2.63×10 m/s) of the blade
The paper presents a fundamental study of the polymer flow within a “wave” type screw channel. The analysis is performed on an “unwrapped” form of a conventional screw channel and a “wave” type channel of similar size. A 3D Finite Element Method
(FEM) simulation was used to simulate the flow field and flow characteristics of the wave channel are compared relative to the plain channel.
An artificial intelligence based improved classification of two-phase flow patte...ISA Interchange
Flow pattern recognition is necessary to select design equations for finding operating details of the process and to perform computational simulations. Visual image processing can be used to automate the interpretation of patterns in two-phase flow. In this paper, an attempt has been made to improve the classification accuracy of the flow pattern of gas/ liquid two- phase flow using fuzzy logic and Support Vector Machine (SVM) with Principal Component Analysis (PCA). The videos of six different types of flow patterns namely, annular flow, bubble flow, churn flow, plug flow, slug flow and stratified flow are re- corded for a period and converted to 2D images for processing. The textural and shape features extracted using image processing are applied as inputs to various classification schemes namely fuzzy logic, SVM and SVM with PCA in order to identify the type of flow pattern. The results obtained are compared and it is observed that SVM with features reduced using PCA gives the better classification accuracy and computationally less intensive than other two existing schemes. This study results cover industrial application needs including oil and gas and any other gas-liquid two-phase flows.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
On Similarity of Differential Capacity and Capillary Pressure FractalKhalid Al-Khidir
On Similarity of Differential Capacity and Capillary Pressure Fractal Dimensions for Characterizing Shajara Reservoirs of the Permo-Carboniferous Shajara Formation, Saudi Arabia
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Modelling study of jet metal interaction in ld processeSAT Journals
Abstract Water model experiments have been carried out in a 1/30th scaled down model of the 100 ton LD converter in order to investigate the effect of changing the lance height and the gas flow rate on the penetration depth of liquid with different exit diameters. It is found the penetration depth increases with decreasing nozzle diameter, decreasing the lance height and with increase the gas flow rate. Gas jets impinging onto a gas–liquid interface of a liquid pool are also studied using computational fluid dynamics modeling, which aims to obtain a better understanding of the behavior of the gas jets. The gas and liquid flows are modeled using the volume of fluid technique. The governing equations in the axisymmetric cylindrical coordinates are solved by the CFD simulation using FLUENT. The computed results are compared with experimental result and it isfound a good match with all the data. Keywords: LD process, Water Modeling, Penetration Depth, Volume of Fluid, CFD.
On Modeling Water Transport in Polymer Electrolyte Membrane Fuel Cell_Crimson...Crimson_Biostatistics
On Modeling Water Transport in Polymer Electrolyte Membrane Fuel Cell by Ahmed Kaffel* in OABB
There is a great need to predict liquid water saturation in porous layers such as gas diffusion layers (GDL) and micro porous layers (MPL) of polymer electrolyte membrane fuel cells (PEMFCs) as this is a key parameter in flooding occurrence which is a limiting factor of PEM fuel cell performance. Several models have been developed in order to study water distribution and migration in micro porous layers. These models require heavy computational efforts and doubt in their applicability to the gas diffusion layer (GDL). Recently Qin & Hassanizadeh [1] developed a new approach based on the reduced continua model for modeling multiphase flow through a stack of thin porous layers.
For more open access journals in Crimson Publishers please click on link: https://crimsonpublishers.com/
For more articles in open access Biostatistics journals please click on link: https://crimsonpublishers.com/oabb/
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Evaluation of Morphometric Parameters Derived from CartoDEM and Aster GDEM wi...Dr Ramesh Dikpal
From three different sources viz. survey of India topographic map (1:50,000), CartoDEM (10 mts) and Aster GDEM (30 mts) morphometric parameters are derived and evaluated. Manually digitized the drainage network from toposheets and extracted drainage network system from CartoDEM and Aster GDEM using ArcGIS 10.2 software. Basic, derived and shape parameters are considered for basin analysis. The mean bifurcation ratio of the given basin for CartoDEM & Aster GDEM are having nearby values and also indicates some sort of geological control, high stream frequency (Fs) is indicative of high relief and low infiltration capacity of the bedrock pointing towards the increase in stream population with respect to increase in drainage density, low drainage density (Dd) leads to coarse drainage texture, value of Lg for topographic, CartoDEM and Aster GDEM data indicating very fine texture & fine texture respectively. From the shape parameters the Kumudvathi watershed indicates it is sub-circular and elongated. The results from the high resolution data will have the nearby values and less of % variation, whereas in low resolution data % of variation is more and will not meet criteria.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The effect of rotational speed variation on the velocity vectors in the singl...IOSR Journals
The current investigation is aimed to simulate the three-dimensional complex internal flow in a
centrifugal pump impeller with five twisted blades by using a specialized computational fluid dynamics (CFD)
software ANSYS /FLUENT 14code with a standard k-ε two-equation turbulence model.
A single blade passage will be modeled to give more accurate results for velocity vectors on (blade, hub, and
shroud). The potential consequences of velocity vectors associated with operating a centrifugal compressor in
variable rotation speed.
A numerical three-dimensional, through flow calculations to predict velocity vectors through a
centrifugal pump were presented to examined the effect of rotational speed variation on the velocity vectors of
the centrifugal pump . The contours of the velocity vectors of the blade, hub, and shroud indicates low velocity
vectors in the suction side at high rotational speed (over operation limits )and the velocity vectors increases
gradually until reach maximum value at the leading edge (2.63×10 m/s) of the blade
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology
Effects of Surface Roughness and Fluid on Amplifier of Jet Pipe Servo Valvetheijes
In manufacturing process of jet pipe electro-hydraulic servo valve, it must be having a lot of errors in the inner wall of servo valve components, which fluid flows will have a certain roughness. Jet pipe electro-hydraulic servo valve, in fact, can use variety of fluid during its working. With CFX software, this article studies effect of surface roughness of parts and working fluid on pressure characteristics of amplifier of pilot stage in jet pipe servo valve. Through mathematical models and simulation, it is shown that effect of wall roughness of parts on flow characteristics of the pilot stage amplifier is much. Analysis of many different roughness, it is found out that the greater surface roughness is, the smaller velocity of jet flow is, and the recovery pressure decreases but the magnitude of change is not much. In addition, the relationship between the viscosity of fluid and the pressure characteristics of the pilot stage is close
lab 4 requermenrt.pdf
MECH202 – Fluid Mechanics – 2015 Lab 4
Fluid Friction Loss
Introduction
In this experiment you will investigate the relationship between head loss due to fluid friction and
velocity for flow of water through both smooth and rough pipes. To do this you will:
1) Express the mathematical relationship between head loss and flow velocity
2) Compare measured and calculated head losses
3) Estimate unknown pipe roughness
Background
When a fluid is flowing through a pipe, it experiences some resistance due to shear stresses, which
converts some of its energy into unwanted heat. Energy loss through friction is referred to as “head
loss due to friction” and is a function of the; pipe length, pipe diameter, mean flow velocity,
properties of the fluid and roughness of the pipe (the later only being a factor for turbulent flows),
but is independent of pressure under with which the water flows. Mathematically, for a turbulent
flow, this can be expressed as:
hL=f
L
D
V
2
2 g
(Eq.1)
where
hL = Head loss due to friction (m)
f = Friction factor
L = Length of pipe (m)
V = Average flow velocity (m/s)
g = Gravitational acceleration (m/s^2)
Friction head losses in straight pipes of different sizes can be investigated over a wide range of
Reynolds' numbers to cover the laminar, transitional, and turbulent flow regimes in smooth pipes. A
further test pipe is artificially roughened and, at the higher Reynolds' numbers, shows a clear
departure from typical smooth bore pipe characteristics.
Experiment 4: Fluid Friction Loss
The head loss and flow velocity can also be expressed as:
1) hL∝V −whe n flow islaminar
2) hL∝V
n
−whe n flow isturbulent
where hL is the head loss due to friction and V is the fluid velocity. These two types of flow are
seperated by a trasition phase where no definite relationship between hL and V exist. Graphs
of hL −V and log (hL) − log (V ) are shown in Figure 1,
Figure 1. Relationship between hL ( expressed by h) and V ( expressed by u ) ;
as well as log (hL) and log ( V )
Experiment 4: Fluid Friction Loss
Experimental Apparatus
In Figure 2, the fluid friction apparatus is shown on the right while the Hydraulic bench that
supplies the water to the fluid friction apparatus is shown on the left. The flow rate that the
hydraulic bench provides can be measured by measuring the time required to collect a known
volume.
Figure 2. Experimental Apparatus
Experimental Procedure
1) Prime the pipe network with water by running the system until no air appears to be discharging
from the fluid friction apparatus.
2) Open and close the appropriate valves to obtain water flow through the required test pipe, the four
lowest pipes of the fluid friction apparatus will be used for this experiment. From the bottom to the
top, these are; the rough pipe with large diameter and then smooth pipes with three successively
smaller diameters.
3) Measure head loss ...
Effect of Geometry on Variation of Heat Flux and Drag for Launch Vehicle -- Z...Abhishek Jain
Above Research Paper can be downloaded from www.zeusnumerix.com
The research paper aims at studying the variation of the geometry of the launch vehicle nose and its effect on heat flux. CFDExpert software is first validated on NASA's hyperballistic model and then used on proposed geometries. Various nose radius and blending shapes are studied for effect on drag and heat flux. Cone ogive shape is found to decrease heat flux with an insignificant increase in drag. Authors Abhishek Jain (Zeus Numerix), Rohan Kedar and Prof V Kalamkar (SPCOE).
International Journal of Engineering Research and Development is an international premier peer reviewed open access engineering and technology journal promoting the discovery, innovation, advancement and dissemination of basic and transitional knowledge in engineering, technology and related disciplines.
We follow "Rigorous Publication" model - means that all articles appear on IJERD after full appraisal, effectiveness, legitimacy and reliability of research content. International Journal of Engineering Research and Development publishes papers online as well as provide hard copy of Journal to authors after publication of paper. It is intended to serve as a forum for researchers, practitioners and developers to exchange ideas and results for the advancement of Engineering & Technology.
1. An Investigative Study of Microfluidic Capabilities of Star-CCM+
Harpreet S. Matharoo
Department of Mechanical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New
Delhi 110016 INDIA.
Abstract
Flow in microchannels studied using Star-CCM+ is presented. Firstly, single phase flow in
prismatic channels of rectangular and circular cross section is modeled. The velocity profile is
validated against the analytical profile for both the cases. Then, Droplet formation in
microfluidic T-junction and microfluidic flow focusing device is study. The volume-of-fluid
(VOF) method has been employed to model the devices. However, very high spurious currents
and thick interface were observed, when a coarse mesh was used near the interface. These
currents were found to be reducing as the mesh was refined. So, to minimize these currents and
to sharpen the interface adaptive mesh refinement (AMR) technique was employed.
Introduction
Fluid flow in Microchannel (with characteristic dimension less than 1000 m) has attracted a
large amount of audience in past two decades because of its great potential and application in
micro devices. Some of these applications include micro-scaled cooling of high power
generating electronic micro-devices such as microchips. Another application of microfluidics is
controlled droplet formation in Microchannels. Droplets at microscopic scales are useful in wide
range of applications particularly when the size of the droplet and the frequency of the droplet
formation can be controlled. Droplets in Microchannels form the centerpiece of many lab-on-a-
chip devices. For example, droplets can be moved around as a means of pumping fluids. Another
2. 1
application is the use of droplets as chemical reactors where the kinetics can be monitored and
controlled precisely. Droplets have also been used as templates for producing micro-particles
with specialized biological, chemical, and optical properties. Creation of mono-disperse
emulsions requires microfluidic channels for droplet formation as traditional methods produce
droplets of varying sizes [1].
However, many unexpected phenomena have been reported when dealing with micro-flows [2].
The limited available data show behavior that is either exactly same or significantly different
from the macroscopic behavior and theory. The reason for this anomaly has been attributed to
micro-effects, which become significant as the characteristic length scale decreases. Some of
these micro-effects include high lateral momentum diffusion, surface forces etc. Also, the
applicability of continuum hypothesis is questionable.
The present study investigates the ability of Star-CCM+ to model flows in Microchannels. Flows
for low Knudsen number have been studied to eliminate inapplicability of continuum hypothesis.
Firstly, flow characteristics (velocity profile and pressure gradient) of simple flow in
Microchannels of rectangular and circular cross section were validated.
After validating the single phase flow model, multiphase flow in Microchannels was validated by
modeling Droplet formation in a Microfluidic T-junction and a Microfluidic flow focusing
device.
A schematic diagram of T-junction is shown in fig. 1. The T-junction geometry consists of a
main channel and a dispersed channel that merge at a right angle. The main channel carries the
continuous fluid (carrier fluid), while the dispersed channel carries the dispersed phase. The T-
junction uses shearing action or pressure forces or both to form Droplets.
3. 2
A schematic of the flow focusing device is shown in fig. 2. There are three inlets to the device
out of which, the outer ones carry the continuous fluid and the inner one carry the dispersed
fluid. The interface is disturbed by forcing the three liquid streams to move through an orifice
placed at a certain distance from the inlet. Depending upon the flow parameters and geometrical
parameters, the disturbance might lead to the breakup of the inner liquid stream into small
droplets, which then flow downstream into the collection tube.
Both the geometries were modeled using Volume of fluid (VOF) because of its ability to
accommodate large surface topology changes including surface rupture and coalescence. Star-
CCM+ was successfully able to model the T-junction, however, very high spurious currents were
observed at the interface and to reduce these currents, adaptive mesh refinement (AMR)
technique was used to model the flow focusing device.
Methodology
Single Phase Flow
Incompressible laminar 3-D Navier-Stokes equations for pressure driven water flow were solved.
Also, no slip at the wall, velocity inlet and pressure outlet were imposed. Periodic boundary
condition was imposed for the rectangular channel, while for circular channel developed velocity
profile for macroscopic channel was imposed at the inlet.
Multiphase Flow and Droplet Formation
Study of droplet formation through numerical modeling imposes a great challenge because of the
complex interfacial dynamics and the formation of singularity at the time of interface breakup
[1]. There have been plenty of methods of available to model droplet formation, which can be
4. 3
categorized into two categories: Sharp interface methods and diffuse interface methods [1]. The
problem of modeling past transition of Droplet formation arises in case of sharp interface
methods because of the formation of singularity at the surface break-up. However, the surface
breakup is implicitly modeled in case of diffuse interface methods, while solving the governing
equations. One of such diffuse interface methods is Volume of fluid (VOF).
Volume of Fluid (VOF)
The VOF is well known for its ability to conserve the mass of the traced fluid and to
accommodate great surface topology changes. This change is traced easily, so the interfaces can
for example join, or break apart.
Mathematical formulation of VOF involves defining a color function C, which assumes a value
of 1 in one phase, 0 in another and fractional value at the interface [3]. Fig. 3 demonstrates how
‘C’ varies with the volume fraction of the fluid.
The properties of the fluid in the domain are defined as the function of C. Any general property
at any grid point is defined as:
( )
Where are the properties of fluids ‘c’ and ‘d’ respectively.
VOF solver involves an additional advection equation along with the momentum equations and
the continuity equation. The advection equation is as follows:
5. 4
Since, every fluid parcel retains the color that it was assigned while the fluid parcel moves in the
domain, the total derivative of the color is zero.
We used a second order discretization scheme for the convection term. Also, an antidiffusion
step was added to sharpen the interface. An antidiffusion (or sharpening) factor of 0.7 was used.
Adaptive Mesh Refinement (AMR)
A dynamics mesh was used, which refines after every few computation time steps. The mesh
was made to be very fine near the interface and coarse for far from the interface. The mesh base
size at each point is decided by the volume of fraction of any of the fluid.
Results
Single Phase Flow
Flow characteristics (velocity profile and pressure distribution) for both the channels are in
prediction of macroscopic theory. Velocity profiles for circular channel are shown in fig. 4. It
can be seen that the velocity profile obtained matches with the analytical profile predicted from
the macroscopic theory within an error of 3%. However, the velocity scalar scene in fig. 5 shows
that the velocity profile imposed at the inlet does not exactly match with the actual developed
profile.
Fig. 6 shows the velocity profile obtained in rectangular channel being compared with the
analytical profile. It can be seen that the obtained velocity profile is within macroscopic
prediction. Velocity scalar scene of the domain is shown in fig. 7.
Multiphase Flow
6. 5
Microfluidic T-junction
The dimensions of microfluidic T-junction are takes as shown in fig. 8. The flow rate ratio
( ⁄ ) and Ca ( ⁄ ), where the subscripts ‘c’ and ‘d’ represent the continuous fluid and
the dispersed fluid respectively, were taken to be 0.25 and 5x10-3
respectively. Since, the
capillary number was very small, the droplet formation for this case was surface forces
dominated and the role of viscous forces in droplet formation was negligible.
Fig. 9 shows a timeline of droplet formation in microfluidic T-junction. The droplet size and the
mechanism of break-up is exactly the same as predicted by Garstecki et al [4]. However, very
high spurious currents were observed at the interface, because of which the time step was
reduced to satisfy the CFL condition. Velocity scalar scenes for same interface location and
different mesh sizes are shown in fig 10. It can be seen that the spurious currents tend to decrease
as a finer mesh is taken.
Microfluidic Flow Focusing Device
Dimensions of the device are as same as the one taken by Shelly et al [5]. The flow rate ratio and
Ca were taken to be 0.25 and 7.2X10-3
. Star-CCM+ successfully modeled the device within
reasonable computation time.
Also, based on the observation of T-junction modeling, adaptive mesh refinement technique is
applied. The mesh is made very fine near the interface and the mesh changes as the interface
moves. Fig. 11 shows a series of snapshots of the mesh as the dispersed phase advances in the
device. Because of a very fine dynamic mesh, a thin interface is obtained. Since, the mesh is very
fine at the interface the spurious currents are minimized, which saves the computation time. So,
7. 6
the adaptive mesh technique is an effective method of modeling interfacial flows and capturing
very sharp interface.
REFERENCES
1. V. Cristini and Y. Tan, The Royal Society of Chemistry, 4, 257-264 (2004)
2. G. Hetsroni, A. Mosyak, E. Pogrebnyak and L. P. Yarin, International Journal of Heat
and Mass Transfer, 48, 1982–1998 (2005)
3. C. W. Hirt and B. D. Nicolas, Journal of Computational Physics ,39 , 201-225 (1981)
4. P. Garstecki, M. J. Fuertsman, H. A. Stone and G. M. Whitesides, The Royal Society of
Chemistry, 6, 437–446 (2006)
5. S. L. Anna, N. Bontoux and H. A. Stone, Applied Physics Letter, 82, 364–36 (2003)
Figure 1 A schematic diagram of the microfluidic T-junction
Figure 2 A schematic diagram of the microfluidic T-junction
8. 7
Figure 3 Variation of the color function in the domain with the volume fraction of the fluid
Figure 4 Validation of velocity profile with the analytical solution. Solid line represents the analytical velocity profile for
macroscopic channels.
Figure 5 Velocity scalar scene of the circular channel
r/R
9. 8
Figure 6 Validation of the velocity profile with the analytical solution. Here, H and W are the height and width of the channel,
and X and Y are the coordinates along the width and the height measured from the mid-section of the channel. Solid line
represents the analytical velocity profile for macroscopic channels.
Figure 7 Velocity scalar scene of the rectangular channel
10. 9
Figure 8 Orthographic view of the T-junction geometry taken for computation modeling
Figure 9 Timeline of Droplet formation in Microfluidic T-junction
11. 10
Figure 10 Velocity scalar scene of the T-junction for different mesh base size,
Figure 11 An illustration of adaptive mesh refinement
12. 11
Figure 12 An illustration of droplet formation in microfluidic flow focusing device