Flow over an Erodible Broad Crested WeirIJERA Editor
The overtopping flow of water over an earthen embankment causes erosion of soil from its surfaces and the eroded surface of the embankment acts as a Broad crest weir. But the longitudinal profile of the weir goes on changing with time of erosion. Hence crest height of the weir goes changing in accelerated flow condition. In this paper, the discharge equation for this type of flow situation is established for different types of soils used in the embankment. Then, the experiments have been carried out as the analogous rigid beds of the captured eroded profiles at any time of erosion of the broad crested weir to compare the discharge equation and to study the energy loss in dislodging the soil from the surface of the weir and transporting them down stream.
Flow over an Erodible Broad Crested WeirIJERA Editor
The overtopping flow of water over an earthen embankment causes erosion of soil from its surfaces and the eroded surface of the embankment acts as a Broad crest weir. But the longitudinal profile of the weir goes on changing with time of erosion. Hence crest height of the weir goes changing in accelerated flow condition. In this paper, the discharge equation for this type of flow situation is established for different types of soils used in the embankment. Then, the experiments have been carried out as the analogous rigid beds of the captured eroded profiles at any time of erosion of the broad crested weir to compare the discharge equation and to study the energy loss in dislodging the soil from the surface of the weir and transporting them down stream.
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.
International Journal of Engineering Inventions (IJEI) provides a multidisciplinary passage for researchers, managers, professionals, practitioners and students around the globe to publish high quality, peer-reviewed articles on all theoretical and empirical aspects of Engineering and Science.
The peer-reviewed International Journal of Engineering Inventions (IJEI) is started with a mission to encourage contribution to research in Science and Technology. Encourage and motivate researchers in challenging areas of Sciences and Technology.
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.
A clear water scour around a circular bridge pier under steady flow for diffe...eSAT Journals
Abstract The loose non cohesive material through which a river flows is generally called sediment. Local scour at piers and abutments is the main reason for the collapse of bridges founded in alluvial sediments. Clear water scour refers to the situation where no sediment is supplied by the approaching flow in the zone of scour. Many investigators have studied various aspects of scour. However, the study on scour under steady condition for same discharge with same depth of flow for different pier diameters is limited. In present study laboratory experiment was conducted on different pier sizes of circular piers by keeping discharge constant under clear water scour condition. It is found that Non dimensional scour depth gradient is different up to opening ratio 0.8 having less slope and its slope is steep above 0.8 opening ratio. Keywords: -clear water scour; Froude’s number; sediment; equilibrium scour.
Topics:
1. Introduction to Fluid Dynamics
2. Surface and Body Forces
3. Equations of Motion
- Reynold’s Equation
- Navier-Stokes Equation
- Euler’s Equation
- Bernoulli’s Equation
- Bernoulli’s Equation for Real Fluid
4. Applications of Bernoulli’s Equation
5. The Momentum Equation
6. Application of Momentum Equations
- Force exerted by flowing fluid on pipe bend
- Force exerted by the nozzle on the water
7. Measurement of Flow Rate
a). Venturimeter
b). Orifice Meter
c). Pitot Tube
8. Measurement of Flow Rate in Open Channels
a) Notches
b) Weirs
This pdf includes about the submerged bodies and the forces acting on the submerged bodies. Different terminologies are discussed. Definitions of different bodies in the fluid are discussed as well.
It is small pdf with great knowledge, hope it will be helpful to the students.
Fluid Mechanics-Shear stress ,Shear stress distribution,Velocity profile,Flow Of Viscous Fluid Through The circular pipe ,Velocity profile for turbulent flow Boundary layer buildup in pipe,Velocity Distributions
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
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.
International Journal of Engineering Inventions (IJEI) provides a multidisciplinary passage for researchers, managers, professionals, practitioners and students around the globe to publish high quality, peer-reviewed articles on all theoretical and empirical aspects of Engineering and Science.
The peer-reviewed International Journal of Engineering Inventions (IJEI) is started with a mission to encourage contribution to research in Science and Technology. Encourage and motivate researchers in challenging areas of Sciences and Technology.
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.
A clear water scour around a circular bridge pier under steady flow for diffe...eSAT Journals
Abstract The loose non cohesive material through which a river flows is generally called sediment. Local scour at piers and abutments is the main reason for the collapse of bridges founded in alluvial sediments. Clear water scour refers to the situation where no sediment is supplied by the approaching flow in the zone of scour. Many investigators have studied various aspects of scour. However, the study on scour under steady condition for same discharge with same depth of flow for different pier diameters is limited. In present study laboratory experiment was conducted on different pier sizes of circular piers by keeping discharge constant under clear water scour condition. It is found that Non dimensional scour depth gradient is different up to opening ratio 0.8 having less slope and its slope is steep above 0.8 opening ratio. Keywords: -clear water scour; Froude’s number; sediment; equilibrium scour.
Topics:
1. Introduction to Fluid Dynamics
2. Surface and Body Forces
3. Equations of Motion
- Reynold’s Equation
- Navier-Stokes Equation
- Euler’s Equation
- Bernoulli’s Equation
- Bernoulli’s Equation for Real Fluid
4. Applications of Bernoulli’s Equation
5. The Momentum Equation
6. Application of Momentum Equations
- Force exerted by flowing fluid on pipe bend
- Force exerted by the nozzle on the water
7. Measurement of Flow Rate
a). Venturimeter
b). Orifice Meter
c). Pitot Tube
8. Measurement of Flow Rate in Open Channels
a) Notches
b) Weirs
This pdf includes about the submerged bodies and the forces acting on the submerged bodies. Different terminologies are discussed. Definitions of different bodies in the fluid are discussed as well.
It is small pdf with great knowledge, hope it will be helpful to the students.
Fluid Mechanics-Shear stress ,Shear stress distribution,Velocity profile,Flow Of Viscous Fluid Through The circular pipe ,Velocity profile for turbulent flow Boundary layer buildup in pipe,Velocity Distributions
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
The Hydrodynamic Performance Examination of a New Floating Breakwater Configu...IJAEMSJORNAL
It is critical to protect coastal and offshore structures. Most current studies and scientific investigations are centered on how to protect seashore with an efficient and cost-effective system. This study involved the testing of a new floating breakwater configuration (FB). A series of experiments were carried out in the lab of The Higher Institute of Engineering (El-shorouk City) on the new model and the traditional vertical plane FB without a curved face to compare their behaviours and performance in wave attenuation. The incident, reflected, and transmitted wave heights were measured, and the coefficients of reflection, transmission, and energy dissipation were calculated using these measurements. In terms of hydrodynamic performance, the curved-face floating breakwater outperformed the traditional vertical floating breakwater, according to the study's highlights. The curved face model significantly reduced wave transmission values when compared to the traditional vertical configuration. The greater the concavity of the curve, the better the model handles waves, especially when the wave steepness is low.
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
Open channel flow velocity profiles for different reynolds numbers and roughn...eSAT Journals
Abstract A series of laboratory tests were carried out to understand the extent of effect of roughness and Reynolds number on mean velocity in both outer and inner scaling. To this end, four different types of bed surface conditions (impermeable smooth bed, impermeable rough bed, permeable sand bed and impermeable distributed roughness) and two different Reynolds number (Reh = 47,500 and 31,000) were adopted in the study. Sand particles of median diameter of 2.46 mm were used to create the roughness. The results show that the mean velocities collapsed well for different Reynolds number and for all different bed surfaces. The maximum velocity for all flow conditions were observed below some distances from the free surface. The location of maximum velocity is seen to be dependent on both of roughness and Reynolds number. The smooth bed test data agrees well with the standard log law and collapses well in viscous sub layer and overlap region. The extent of collapses is found to be dependent on Reynolds number. Friction coefficient is noted to be dependent on both the Reynolds number and roughness. Key Words: Open channel flow, Reynolds number, Roughness, mean velocity, friction coefficient, log law
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.
Effect of free surface wave on free vibration of a floating platformeSAT Journals
Abstract Use of floating structures is very common and widespread. Starting from boats, ships and submarines they are used these days for various purposes like platforms for industrial use like offshore oil exploration, civic amenities like floating air strips, defense bases and in some island nations for recreation and habitation. Hence, strength and stability of these platforms are very important. In the present study, the fluid-structure interaction effect on the free vibration frequency of a floating platform is investigated. The fluid is treated as inviscid, incompressible and having a small amplitude irrotational motion. The platform is considered to be of rectangular in size and is made of homogeneous material following Hooke’s law. Finite element technique is adopted for the solution of this problem with eight noded brick elements for the fluid and four noded quadrilateral elements for the plate. The interaction problem of the platform and the fluid is solved independently for the platform and the fluid domain by transferring the pressure to the platform from the fluid and the acceleration of the platform to the fluid sequentially. The effects of the surface wave, thickness and aspect ratio of the platform on free vibration frequencies are studied. It is observed that surface wave reduces the free vibration frequencies significantly for frequencies those are due to the bulging modes of the platform. Key words: - Inviscid, Irrotational, Hydro elasticity, Eigen frequencies, Eigen value.
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.
Effect of Gap between Airfoil and Embedded Rotating Cylinder on the Airfoil A...CrimsonPublishersRDMS
Effect of Gap between Airfoil and Embedded Rotating Cylinder on the Airfoil Aerodynamic Performance by Najdat Nashat Abdulla* in Crimson Publishers: Peer Reviewed Material Science Journals
Control of Suddenly Expanded Flow at Low Supersonic Mach NumbersIJERA Editor
In the present study the experiments were conducted to control the base pressure from a convergent-divergent
nozzle at low supersonic Mach numbers to assess the effectiveness of active control mechanism in the form of
micro jets at different expansion level. The parameters considered in the present study are the diameter ratio,
length to diameter ratio (L/D), Nozzle Pressure Ratio (NPR), and the Mach number. The diameter ratio selected
for the present study are 1.6, 1.8, 2.2, and 2.5. Experiments were conducted for nozzle pressure ratio (NPR)
from 3 to 11. The L/D ratio of the enlarged duct was varied from 10 to 1, and results are presented for L/D 4, 3,
2, and 1. The Mach numbers of the present studies are 1.1, 1.2, 1.4, and 1.5. The results show that the Micro jets
are very effective and are able to raise the base pressure value to a considerable level under the influence of
favorable pressure gradient except at lower NPR 3. At NPRs 5 and 7 for some cases the trends differ due to the
level of expansion, nature of waves present in the base region, relief available to the flow, L/D ratio of the
enlarged duct and the Mach numbers. It is seen that most of the cases exhibit similar behavior for the L/Ds in
the range 4 and 3, which means; that the back pressure has not adversely influenced the flow field in the base
region as well as in the duct. The minimum duct length required for the flow to be attached is L/D = 2, even
though in some cases flow is attached with duct wall. With this it can be stated that the micro jets can be an
alternative for the for base pressure control.
Experimental and Numerical Investigation of Vortex-Induced Vibration for a Fully Submerged Oscillating Circular Cylinder in a Circulating Water Channel
1. c
+X
+Y
+Z
h
S
Atmospheric Ventilation
High-speed marine vehicles rely upon propellers and hydrofoils for thrust- and
lift-generation. Such lifting surfaces are often operated at or very near the fluid
free-surface, making them vulnerable to atmospheric ventilation, where
atmospheric air is entrained into low-pressure regions of flow. Ventilation can
occur suddenly [1,2], inducing large dynamic load changes. Reductions of lift
of up to 75% [1] and even lift-reversal [3] can occur.
Relevance:
Ventilation has implications in the safety and controllability of any vessel that
relies upon ventilation-prone systems. High speed and heavily loaded lifting
surfaces are particularly vulnerable, including propellers and hydrofoils
operating at shallow depths, high-speed hull forms, and dynamic positioning
thrusters in highly loaded conditions. With continued progress toward the use
of lightweight and/or flexible marine structures, fluid-structure interaction (FSI)
and stability of ventilated flows becomes an important consideration. Large
changes in loading may induce vibrations, instabilities or structural failure.
A greater understanding of the physics driving ventilation and its impact upon
the hydrodynamic and structural response of lifting-surfaces in ventilated flows
will enable eventual mitigation and/or control of deleterious ventilation and
flow-induced vibrations.
Objectives:
1. Use a “rigid” aluminum surface piercing hydrofoil/strut to
a.Identify the characteristic ventilation flow regimes through towing-tank
experiments
b. Identify the change in modal response of a partially immersed strut
subjected to ventilation
2. Design and instrument a flexible PVC hydrofoil/strut to measure
instantaneous 3D deformations, quantify changes in added mass &
damping with ventilation, and characterize flow-induced vibrations
Experimental Setup
• Two identical struts manufactured from aluminum and PVC (figure 1)
• Aluminum strut experiments completed using the towing-tank of the
University of Michigan Marine Hydrodynamics Laboratory (figure 2, table 1)
• Dry and wet modal response measured for aluminum strut (figure 3).
• PVC strut instrumented with shape-sensing beams
Hydrodynamic and Structural Response of Surface-Piercing Struts in Ventilated Flows
Casey Harwood, Prof. Julie Young, Prof. Steven Ceccio
University of Michigan, Ann Arbor, USA
Characteristic Flow Regimes – Al Strut
Conclusions
Chord 𝑐 11in (29.7cm)
Foil Span 𝑆 36in (91cm)
Yaw Angle 𝛼 −5∘ to 30∘
Tip Depths ℎ
5.5,11,16.5 in
(14,28,42 cm)
Aspect Ratio 𝐴𝑅ℎ = ℎ/𝑐 0.5, 1.0, 1.5
Velocities 𝑈∞
2-20 ft/s
(0.6-6 m/s)
Depth Froude # 𝐹𝑛ℎ = 𝑈/√𝑔ℎ 0.5 - 4.5
Chord Reynolds # 𝑅𝑒 𝑐 = 𝑈𝑐/𝜈
1.7 × 105 −
1.7 × 106
Table 1: Particulars of tow-tank study
Fully Wetted (FW) Regime
• Suction side remains wetted
• Flow is relatively steady and locally stable
• Base-ventilation can occur in eddying wake
Partially Ventilated (PV) Regime
• Cavity depth (0 < 𝐷 < ℎ) OR Φ > 45∘
• Flow is unsteady and potentially unstable
• Dominated by re-entrant jet
Fully Ventilated (FV) Regime
• 𝐷 = ℎ AND Φ ≤ 45∘
• Flow is relatively steady and stable
• Cavity is open to the atmosphere
• Tip vortex often ingests air from cavity
FW
PV
FV
PV→FV
FW→PV
PV→FW
FV→PV
Steady
Regimes
Transition
Boundaries
Bi-Stable
Regions
FW/FV
FW/PV
PV/FV
Strain Gauge Half-Bridges
0 0.5 1 1.5
0
20
40
60
80
100
120
140
160
180
Submerged Aspect Ratio, ARh
Frequency,Hz
X-Bend 1 (Water-Drum)
X-Bend 2 (Water-Drum)
Z-Twist 3 (Water-Drum)
FA (Carriage)
FV (Carriage)
Shaded regions indicate FEA
results for each mode.
Bounded below by FW and
above by FV frequencies.
Figure 5: Shape-sensing beam (one of two installed in flexible strut)
Effect of Immersion Depth and Ventilation on Modal Frequencies - Al Strut
Figure 4: Flow regimes and stability regions at 𝐴𝑅ℎ = 1.0. Red boundaries indicate ventilation formation (FW → PV → FV).
Blue boundaries indicate closure (FV → PV → FW). Hatched regions indicate bi-stable overlap between locally-stable regimes.
The first three modal frequencies
were measured cases with:
• Strut suspended in drum of water
• Strut being towed (FW & FV flow)
• FEA model (FW & FV flow)
Natural frequencies decrease with
increasing immersion depth and
increase with the onset of ventilation.
The effects are dependent upon
mode shape, leading to a risk of
frequency coalescence and ensuing
instability.
Shape-Sensing with Flexible PVC Strut
Figure 7: Effect of immersion depth and ventilation on
natural frequencies of aluminum strut
Two flexible aluminum spines were installed into channels
machined into the flexible PVC strut (see figure 1). Each
beam is instrumented with four half-bridges to measure
normal bending strain.
1. The bending equation: 𝜀 𝑏𝑒𝑛𝑑 ≈ −
𝑡
2
𝜕2 𝑦
𝜕𝑥2 .
2. A polynomial is fitted through the measured strains:
εbend x ≈ ai xiNgauges
i=0
3. Integration yields a polynomial :
y x ≈ −
2
t
εbend x dx dx =
ai xi+2
i+1 i+2
Ngauges
i=0
4. y1, y2 yield lateral deflection and twist at each station
Figure 2: Experimental fixture
Figure 2: Semi-ogive cross section of struts
Rigid
Flexible
• Three steady flow regimes are identified. Transition between flow regimes occurs where the
stability regions meet or overlap one another.
• Increasing depth-of-immersion decreases resonant frequencies, indicating increased added
mass. The change in added mass depends upon the mode shape. Ventilation causes a
decrease in added mass, and hence an increase in resonant frequencies, relative to the wetted
frequencies at the same conditions.
• A shape-sensing beam has been designed using strain gages, with which it is possible to
obtain a real-time 3D deformation field on a flexible strut with high precision.
Understanding how ventilation and material properties affect the hydrodynamic and structural
performance of lifting surfaces, combined with the ability to measure hydroelastic responses in
real-time may open the door for performance/stability enhancement and vibration suppression
via active control.
[1] J. Breslin and R. Skalak, “Exploratory study of ventilated flows about yawed surface-piercing struts,”
NASA, Washington DC, Tech. Rep. 2-23-59W, 1959.
[2] C. Harwood, et al., “Experimental and numerical investigation of ventilation inception and washout
mechanisms of a surface-piercing hydrofoil,” in Proc. 30th Symp. Naval Hydrodynamics, to be published.
[3] R. Rothblum, et al.,“Ventilation, cavitation, and other characteristics of a high speed surface-piercing strut,”
NSRDC Report, no. 3023, 1969
• Perform towing-tank studies with flexible strut
• Explore the effects of ventilation on fluid added mass, damping, and stiffness matrices, flow-
induced vibrations, and hydroelastic stability boundaries (flutter and divergence).
• Develop and validate instantaneous hydrodynamic load mapping algorithm through inverse
FSI analysis of embedded strain gauge data.
Continuing / Future Work
Single-Point
LDV Vibrometer
Load Cell
at Root
3-Axis
Accelerometer
h
Figure 3: Vibration test rig
Figure 6: Photos of
applied loads and real-time
reconstructions of
deformation fields.
(Clockwise from top left:
twisting, two-node bending,
and one-node bending).
Shape sensing captures
deformation distributions
with high precision and a
low noise-floor.
Deflection𝑦,inDeflection𝑦,in
FW
PV PV
FV