scholarly journals Turbulence Characteristics of the Flexible Circular Cylinder Agitator

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 238
Author(s):  
Sharul Sham Dol ◽  
Tshun Howe Yong ◽  
Hiang Bin Chan ◽  
Siaw Khur Wee ◽  
Shaharin Anwar Sulaiman
Keyword(s):  
Circular Cylinder ◽  
Ethylene Vinyl Acetate ◽  
Flexible Cylinder ◽  
Near Wake ◽  
Production Term ◽  
Rigid Cylinder ◽  
Area Of Interest ◽  
Production Values ◽  
The Mean ◽  
Shear Production

A flexible protruding surface was employed as the flow disturbance to promote turbulence at the area of interest. An ultrasonic velocity profiler, UVP technique, was used to study the mean and fluctuating flow properties in the near wake of the rigid and flexible protruding surface in a water tunnel. The polymer based, ethylene-vinyl acetate (EVA) with an aspect ratio of AR = 10, 12, 14, 16 was used as the flexible circular cylinder, and submerged in a flow at Re = 4000, 6000 and 8000. The motion of the cylinder altered the fluid flow significantly. As a means to quantify turbulence, the wakes regions and production terms were analyzed. In general, the flexible cylinders show better capability in augmenting the turbulence than the rigid cylinder. The results show that the turbulence production term generated by the flexible cylinder is higher than that of rigid cylinder. The localized maximum shear production values have increased significantly from 131%, 203% and 94% against their rigid counterparts of AR = 16 at the Re = 4000, 6000 and 8000, respectively. The performance of turbulence enhancement depends heavily on the motion of the cylinder. The findings suggest that the turbulence enhancement was due to the oscillation of the flexible cylinder. The results have concluded that the flexible cylinder is a better turbulence generator than the rigid cylinder, thus improving the mixing of fluid through augmented turbulent flow.

scholarly journals The drag-adjoint field of a circular cylinder wake at Reynolds numbers 20, 100 and 500

2013 ◽  
Vol 730 ◽  
pp. 145-161 ◽  
Author(s):  
Qiqi Wang ◽  
Jun-Hui Gao
Keyword(s):  
Circular Cylinder ◽  
Flow Field ◽  
Unsteady Flow ◽  
Numerical Solutions ◽  
Reynolds Numbers ◽  
Adjoint Equations ◽  
Cylinder Wake ◽  
Near Wake ◽  
Navier Stokes Equation ◽  
D 20

AbstractThis paper analyses the adjoint solution of the Navier–Stokes equation. We focus on flow across a circular cylinder at three Reynolds numbers, ${\mathit{Re}}_{D} = 20, 100$ and $500$. The quantity of interest in the adjoint formulation is the drag on the cylinder. We use classical fluid mechanics approaches to analyse the adjoint solution, which is a vector field similar to a flow field. Production and dissipation of kinetic energy of the adjoint field is discussed. We also derive the evolution of circulation of the adjoint field along a closed material contour. These analytical results are used to explain three numerical solutions of the adjoint equations presented in this paper. The adjoint solution at ${\mathit{Re}}_{D} = 20$, a viscous steady state flow, exhibits a downstream suction and an upstream jet, the opposite of the expected behaviour of a flow field. The adjoint solution at ${\mathit{Re}}_{D} = 100$, a periodic two-dimensional unsteady flow, exhibits periodic, bean-shaped circulation in the near-wake region. The adjoint solution at ${\mathit{Re}}_{D} = 500$, a turbulent three-dimensional unsteady flow, has complex dynamics created by the shear layer in the near wake. The magnitude of the adjoint solution increases exponentially at the rate of the first Lyapunov exponent. These numerical results correlate well with the theoretical analysis presented in this paper.

scholarly journals Complications in Mandibular Midline Distraction

2017 ◽  
Vol 10 (3) ◽  
pp. 204-207 ◽  
Author(s):  
Jan Pieter de Gijt ◽  
Atilla Gül ◽  
Eppo B. Wolvius ◽  
Karel G.H. van der Wal ◽  
Maarten J. Koudstaal
Keyword(s):  
Retrospective Cohort ◽  
Mental Nerve ◽  
Safe Method ◽  
Congenital Deformities ◽  
Area Of Interest ◽  
Sensory Disturbances ◽  
History Of ◽  
The Mean ◽  
New Surgical Technique

Mandibular midline distraction (MMD) is a relatively new surgical technique for correction of transverse discrepancies of the mandible. This study assesses the amount and burden of complications in MMD. A retrospective cohort study was performed on patients who underwent MMD between 2002 and 2014. Patients with congenital deformities or a history of radiation therapy in the area of interest were excluded. Patient records were obtained and individually assessed for any complications. Complications were graded using the Clavien-Dindo classification system (CDS). Seventy-three patients were included of which 33 were males and 40 were females. The mean follow-up was 2.1 years. Twenty-nine patients had minor complications, grades I and II. Two patients had a grade IIIa and three patients had a grade IIIb complication. Common complications were pressure ulcers, dehiscence, and (transient) sensory disturbances of the mental nerve. This study shows that although MMD is a relatively safe method, complications can occur. Mostly the complications are mild, transient, and manageable without the need for any reoperation.

Laminar Near Wake of a Circular Cylinder at Hypersonic Speeds

AIAA Journal ◽  
2010 ◽  
Vol 48 (1) ◽  
pp. 236-248 ◽  
Author(s):  
Gisu Park ◽  
Sudhir L. Gai ◽  
Andrew J. Neely
Keyword(s):  
Circular Cylinder ◽  
Near Wake ◽  
Hypersonic Speeds

A STUDY OF MORPHOLOGY AND GROSS ANOMALIES IN FULL-TERM PLACENTAE

2021 ◽  
Vol 5 (9) ◽  
Author(s):  
M Pranay Kumar ◽  
Shaik Arshad Rajmohammad
Keyword(s):  
Gas Exchange ◽  
Fetal Development ◽  
Cerebellar Hypoplasia ◽  
Medical Sciences ◽  
Morphological Variations ◽  
Pathologic Evaluation ◽  
Area Of Interest ◽  
History Of ◽  
The Mean ◽  
Gross Examination

Background: Placenta is an important connecting organ between the mother and fetus. It provides nutrition, gas exchange, waste removal, immune support, and endocrine functions. Since variations of the placenta result in effects on fetal development and neonatal survival it is the area of interest to be studied by anatomists, pathologists, and obstetricians. We in the current studied the placental morphology, variations, and abnormalities of the human placenta. Methods: The samples comprised of a collection of placentae in the Department of Anatomy of Prathima Institute of Medical Sciences, Karimnagar. Samples were collected after delivery, placentae were mopped to remove any clotted blood, and then weighed with 10 cm of the umbilical cord. The specimen is fixed in 10% formalin immediately over 24-48 hours and then subjected to thorough gross examination. Results: Out of n=60 placentae studied the mean weight of the placenta was found to be highest at 38 weeks of gestation with a mean surface area of 964.46 cm2 and mean weight of 463.75 Kgs. N=49(81.67%) were normal maternal conditions and history of abortions and pre-eclampsia was in n=2 cases each and oligohydramnios in n=3 cases. Among the fetal abnormalities Anencephaly, Macrostomia, MS/TS/Cerebellar hypoplasia, and holoprosencephaly with single nostril was found in n=1(1.67%) cases each. Conclusion: Examination of the placenta performed in the delivery room provides information that may be important to the care of both mother and infant. The findings of this assessment should be documented in the delivery records. The placenta should be submitted for pathologic evaluation if an abnormality is detected. Keywords: Placenta, Morphological Variations, Anencephaly, oligohydramnios, Macrostomia.

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