scholarly journals VELOCITY MEASUREMENTS OF TURBULENT WAKE FLOW OVER A CIRCULAR CYLINDER

2016 ◽  
Vol 42 ◽  
pp. 1660182
Author(s):  
CHANG-LUNG SHIH ◽  
WEI-CHENG CHEN ◽  
KEH-CHIN CHANG ◽  
MUH-RONG WANG
Keyword(s):  
Circular Cylinder ◽  
Accurate Determination ◽  
Diagnostic Techniques ◽  
Turbulent Wake ◽  
Wake Flow ◽  
Optical Methods ◽  
Velocity Measurements ◽  
Flow Measurements ◽  
Non Invasive ◽  
Comparison Results

There are two general concerns in the velocity measurements of turbulence. One is the temporal characteristics which governs the turbulent mixing process. Turbulence is rotational and is characterized by high levels of fluctuating vorticity. In order to obtain the information of vorticity dynamics, the spatial characteristics is the other concern. These varying needs can be satisfied by using a variety of diagnostic techniques such as invasive physical probes and non-invasive optical instruments. Probe techniques for the turbulent measurements are inherently simple and less expensive than optical methods. However, the presence of a physical probe may alter the flow field, and velocity measurements usually become questionable when probing recirculation zones. The non-invasive optical methods are mostly made of the foreign particles (or seeding) instead of the fluid flow and are, thus, of indirect method. The difference between the velocities of fluid and foreign particles is always an issue to be discussed particularly in the measurements of complicated turbulent flows. Velocity measurements of the turbulent wake flow over a circular cylinder will be made by using two invasive instruments, namely, a cross-type hot-wire anemometry (HWA) and a split-fiber hot-film anemometry (HFA), and a non-invasive optical instrument, namely, particle image velocimetry (PIV) in this study. Comparison results show that all three employed diagnostic techniques yield similar measurements in the mean velocity while somewhat deviated results in the root-mean-squared velocity, particularly for the PIV measurements. It is demonstrated that HFA possesses more capability than HWA in the flow measurements of wake flow. Wake width is determined in terms of either the flatness factor or shear-induced vorticity. It is demonstrated that flow data obtained with the three employed diagnostic techniques are capable of yielding accurate determination of wake width.

Control of the turbulent wake flow behind a circular cylinder by asymmetric sectoral hydrophobic coatings

2021 ◽  
Vol 33 (12) ◽  
pp. 121703
Author(s):  
Anatoliy Lebedev ◽  
Konstantin Dobroselsky ◽  
Alexey Safonov ◽  
Sergey Starinskiy ◽  
Veronica Sulyaeva ◽  
...  
Keyword(s):  
Circular Cylinder ◽  
Turbulent Wake ◽  
Wake Flow ◽  
Hydrophobic Coatings

Detailed Flow Measurements in a Centrifugal Compressor Vaneless Diffuser

1994 ◽  
Vol 116 (3) ◽  
pp. 453-460 ◽  
Author(s):  
A. Pinarbasi ◽  
M. W. Johnson
Keyword(s):  
Centrifugal Compressor ◽  
Turbulent Mixing ◽  
Phase Lock Loop ◽  
Wake Flow ◽  
Hot Wire ◽  
Velocity Measurements ◽  
Vaneless Diffuser ◽  
Flow Measurements ◽  
Loop Technique ◽  
Made In

Hot-wire anemometer measurements have been made in the vaneless diffuser of a 1-m-dia low-speed backswept centrifugal compressor using a phase lock loop technique. Radial, tangential, and axial velocity measurements have been made on eight measurement planes through the diffuser. The flow field at the diffuser entry clearly shows the impeller jet-wake flow pattern and the blade wakes. The passage wake is located on the shroud side of the diffuser and mixes out slowly as the flow moves through the diffuser. The blade wakes, on the other hand, distort and mix out rapidly in the diffuser. Contours of turbulent kinetic energy are also presented on each of the measurement stations, from which the regions of turbulent mixing can be deduced.

Detailed Flow Measurements in a Centrifugal Compressor Vaneless Diffuser

1993 ◽  
Author(s):  
Ali Pinarbasi ◽  
Mark W. Johnson
Keyword(s):  
Centrifugal Compressor ◽  
Turbulent Mixing ◽  
Phase Lock Loop ◽  
Wake Flow ◽  
Hot Wire ◽  
Velocity Measurements ◽  
Vaneless Diffuser ◽  
Flow Measurements ◽  
Loop Technique ◽  
Made In

Hot wire anemometer measurements have been made in the vaneless diffuser of a 1 metre diameter low speed backswept centrifugal compressor using a phase lock loop technique. Radial, tangential and axial velocity measurements have been made on eight measurement planes through the diffuser. The flow field at the diffuser entry clearly shows the impeller jet-wake flow pattern and the blade wakes. The passage wake is located on the shroud side of the diffuser and mixes out slowly as the flow moves through the diffuser. The blade wakes, on the other hand, distort and mix out rapidly in the diffuser. Contours of turbulent kinetic energy are also presented on each of the measurement stations, from which the regions of turbulent mixing can be deduced.

Advanced non-invasive diagnostic techniques for visualization and estimation of kidney fibrosis

2021 ◽  
Author(s):  
Anjali Srivastava ◽  
Bhawna Tomar ◽  
Smita Prajapati ◽  
Anil Bhanudas Gaikwad ◽  
Shrikant R. Mulay
Keyword(s):  
Diagnostic Techniques ◽  
Kidney Fibrosis ◽  
Non Invasive

scholarly journals New Equation for Predicting Pipe Friction Coefficients Using the Statistical Based Entropy Concepts

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 611
Author(s):  
Yeon-Woong Choe ◽  
Sang-Bo Sim ◽  
Yeon-Moon Choo
Keyword(s):  
Friction Coefficient ◽  
Accurate Determination ◽  
Mean Velocity ◽  
Friction Coefficients ◽  
Flow Discharge ◽  
Comparison Results ◽  
Flow Loss ◽  
Key Variables ◽  
New Equation

In general, this new equation is significant for designing and operating a pipeline to predict flow discharge. In order to predict the flow discharge, accurate determination of the flow loss due to pipe friction is very important. However, existing pipe friction coefficient equations have difficulties in obtaining key variables or those only applicable to pipes with specific conditions. Thus, this study develops a new equation for predicting pipe friction coefficients using statistically based entropy concepts, which are currently being used in various fields. The parameters in the proposed equation can be easily obtained and are easy to estimate. Existing formulas for calculating pipe friction coefficient requires the friction head loss and Reynolds number. Unlike existing formulas, the proposed equation only requires pipe specifications, entropy value and average velocity. The developed equation can predict the friction coefficient by using the well-known entropy, the mean velocity and the pipe specifications. The comparison results with the Nikuradse’s experimental data show that the R2 and RMSE values were 0.998 and 0.000366 in smooth pipe, and 0.979 to 0.994 or 0.000399 to 0.000436 in rough pipe, and the discrepancy ratio analysis results show that the accuracy of both results in smooth and rough pipes is very close to zero. The proposed equation will enable the easier estimation of flow rates.

scholarly journals Photonics of human saliva: potential optical methods for the screening of abnormal health conditions and infections

2021 ◽  
Author(s):  
Jijo Lukose ◽  
Sanoop Pavithran M. ◽  
Mithun N. ◽  
Ajaya Kumar Barik ◽  
Keerthilatha M. Pai ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Viral Infections ◽  
Clinical Specimen ◽  
Human Saliva ◽  
Medical Diagnostics ◽  
Optical Methods ◽  
Health Conditions ◽  
Personal Health ◽  
Fast Detection ◽  
Non Invasive

AbstractHuman saliva can be treated as a pool of biological markers able to reflect on the state of personal health. Recent years have witnessed an increase in the use of optical devices for the analysis of body fluids. Several groups have carried out studies investigating the potential of saliva as a non-invasive and reliable clinical specimen for use in medical diagnostics. This brief review aims to highlight the optical technologies, mainly surface plasmon resonance (SPR), Raman, and Fourier transform infrared (FTIR) spectroscopy, which are being used for the probing of saliva for diverse biomedical applications. Advances in bio photonics offer the promise of unambiguous, objective and fast detection of abnormal health conditions and viral infections (such as COVID-19) from the analysis of saliva.

Clearance and Non-Invasive Determination of the Hepatic Extraction of Indocyanine Green in Baboons and Man

1983 ◽  
Vol 64 (2) ◽  
pp. 207-212 ◽  
Author(s):  
S. L. Grainger ◽  
P. W. N. Keeling ◽  
I. M. H. Brown ◽  
J. H. Marigold ◽  
R. P. H. Thompson
Keyword(s):  
Indocyanine Green ◽  
Accurate Determination ◽  
Liver Blood Flow ◽  
Compartment Model ◽  
Hepatic Extraction ◽  
Non Invasive ◽  
Two Compartment Model ◽  
Hepatic Extraction Ratio ◽  
Plasma Disappearance Curve

1. The disposition of an intravenous bolus of indocyanine green (ICG) has been studied in healthy man and baboons using a novel analysis of a two compartment pharmacokinetic model. 2. This analysis enabled the hepatic extraction ratio (ER) of dye to be determined solely from the plasma disappearance curve, and the ER determined did not differ from that measured by hepatic vein catheterization. 3. When compared with clearance measured at steady state, the two compartment model gave a significantly more accurate determination of plasma clearance than did the conventional one compartment model. 4. It is concluded that, in health, liver blood flow may be calculated accurately and noninvasively after a single intravenous injection of ICG.

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