On the Study of Stagnation Points on a Circular Cylinder in Presence of a Straight Wall in an Ideal Fluid

1962 ◽  
Vol 29 (4) ◽  
pp. 502-503
Author(s):  
S. R. Majumder
Keyword(s):  
Circular Cylinder ◽  
Ideal Fluid ◽  
Stagnation Points ◽  
Straight Wall

Heat Transfer Characteristics of Non-Uniform Flow Around a Circular Cylinder in a T-Junction Duct

2020 ◽  
Author(s):  
Xiaoyu Wang ◽  
Di Qi ◽  
Tong Li ◽  
Mei Lin ◽  
Hanbing Ke ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Circular Cylinder ◽  
Velocity Ratio ◽  
Correlation Coefficients ◽  
Heat Transfer Characteristics ◽  
Low Velocity ◽  
Stagnation Points ◽  
Transfer Characteristics ◽  
Low Speed Wind Tunnel ◽  
Straight Duct

Abstract Heat transfer characteristics of a circular cylinder in the branch of a T-junction are experimentally investigated in a low-speed wind tunnel with Reynolds number of Rec = 9163. Local and average heat transfer distributions around the circular cylinder are obtained for the cylinder positions from x/Dh=0.5 to 13 and the velocity ratios from 0.117 to 0.614. It is found that the overall heat transfer characteristics in a T-junction duct at high velocity ratio are lower than those at low velocity ratio, and both are higher than those in the straight duct. The local Nusselt number in the T-junction duct is asymmetrical distribution and weakens with increasing velocity ratios and positions of the cylinder. The angles of the front and rear stagnation points in the T-junction duct are the same as those in the straight duct at certain velocity ratio and/or position of the cylinder. However, the angles of the front and rear separation points in the T-junction duct do not match those in the straight duct. Both the heat transfer correlation coefficients and the amplitude ratios increase with increasing positions of the circular cylinder and velocity ratios.

scholarly journals The motion of a stream of finite depth past a body

1915 ◽  
Vol 92 (636) ◽  
pp. 107-121
Keyword(s):  
Circular Cylinder ◽  
Ideal Fluid ◽  
Finite Depth ◽  
Resultant Force ◽  
The Other ◽  
Potential Motion ◽  
The One ◽  
External Forces

When a circular cylinder moves uniformly in an ideal fluid (i.e. frictionless and incompressible) at rest at infinity, the resultant force acting on it is zero, it no external forces act. This is however, only true when the motion is the usual potential motion. Supposing that in addition to the potential stream produced by the motion of the cylinder a circulation around it be considered, the velocity of the fluid is incresased on the one side, an decreased on the other, and this produces a force acting on the cylinder perpendicular to the direction of motion.

scholarly journals Vortex shedding from an impulsively started rotating and translating circular cylinder

1991 ◽  
Vol 233 ◽  
pp. 265-298 ◽  
Author(s):  
Chien-Cheng Chang ◽  
Ruey-Ling Chern
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Numerical Study ◽  
Vortex Method ◽  
Reynolds Numbers ◽  
Speed Ratio ◽  
Stagnation Points ◽  
Time Variations ◽  
Strong Competition ◽  
High Reynolds

A numerical study is made of the flow past an impulsively started rotating and translating circular cylinder using a hybrid vortex method. The Reynolds number (Re) ranges from 103 to 106 while the (counter-rotating) rotating-to-translating speed ratio (α) is increased from 0 to 2. It is found that three basic patterns of vortex shedding can be identified according to the behaviour of the stagnation points associated with the first upper and the first lower vortices. Depending on the parameters Re and α, the rotation may favour the shedding of the first upper vortex, or the first lower vortex (typically at high Reynolds numbers). In a transition region, strong competition for shedding exists between the first two vortices in the form of double transposition of stagnation (closure) points associated with the two vortices. Time variations of lift coefficients characterize different shedding patterns; the cylinder may first experience a substantial maximal downward lift when the first shedding vortex is from the upper wake, or a maximal upward lift otherwise.

scholarly journals II. Flow with circulation

1949 ◽  
Vol 196 (1044) ◽  
pp. 1-31 ◽  
Keyword(s):  
Circular Cylinder ◽  
Exact Solutions ◽  
Compressible Flow ◽  
Incompressible Flow ◽  
Explicit Solution ◽  
Linear Equations ◽  
Stagnation Points ◽  
Direct Generalization ◽  
Flow Past A Cylinder ◽  
Infinite Set

This is a sequel to an earlier paper (Cherry 1947) in which was found a family of exact solutions for compressible flow past a cylinder. In the present paper the solution is extended to the case where the circulation round the cylinder is not zero. The formulae are developed for the case where the circulation is sufficiently small for the existence of a pair of stagnation points on the surface of the cylinder, under the condition that the speed at infinity is subsonic. One substantial point which arises in the present investigation is that the most direct generalization of the formulae for incompressible flow yield multiple-valued formulae for compressible flow. To get a single-valued solution it is necessary to add another multiple-valued solution, involving a set of constants which are to be determined from an infinite set of linear equations. The explicit solution of these equations is found, and hence the flow around a profile which is a slightly distorted circular cylinder.

The scattering of surface waves by two submerged cylinders

1971 ◽  
Vol 69 (1) ◽  
pp. 201-215 ◽  
Author(s):  
Jon T. Schnute
Keyword(s):  
Circular Cylinder ◽  
Surface Waves ◽  
Ideal Fluid ◽  
Periodic Surface ◽  
Reflective Property ◽  
Historical Basis ◽  
Submerged Objects ◽  
Time Periodic

1. Introduction. The historical basis for the work in this paper lies in a remarkable fact discovered by Dean in 1948. He found that time-periodic surface waves in an ideal fluid experience no reflexion when they encounter normally a fixed, submerged, right-circular cylinder. We might reasonably ask if a similar non-reflective property carries over to different geometrical configurations of submerged objects, for example, two or more cylinders. This question motivates the investigation which follows.

Effects of Endplates on Secondary Streaming of Oscillating Flows Past a Circular Cylinder

2008 ◽  
Author(s):  
C. T. Hsu ◽  
Yan Su
Keyword(s):  
Circular Cylinder ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Stokes Number ◽  
Fluid Particle ◽  
Navier Stokes ◽  
Oscillating Flows ◽  
Navier Stokes Equations ◽  
Stagnation Points ◽  
Streaming Flows

The effects of parallel endplates on the secondary streaming of oscillating flows past a circular cylinder are studied by solving the Navier-Stokes equations numerically with Direct Numerical Simulation (DNS) method. A fractional-step scheme was implemented with the incorporation of the spectral method applied along the circumferential direction in solving a set of 2-D Poisson equations. The structure of the secondary streaming flows is presented with three-dimensional fluid particle traces (streak lines) and vorticity distributions. Unlike the traditional secondary streaming of two dimensional oscillating flows that exhibits 8 closed re-circulation zones (two in each quadrant), the mean secondary streaming flows in this study are three-dimensional without closed recirculation. The fluid particle traces show that there are three-dimensional spirals in each quadrant. Fluid particles near the endplates are attracted into the spirals toward the mid-plane of the two endplates. The trace trajectories in the flow domains never interest except at the stagnation points. The effects of cylinder aspect ratio, Keulegan-Carpenter number, and Stokes number on the secondary streaming patterns are also studied. The oscillatory drag and lift coefficients are also computed and discussed. The comparison of flow patterns obtained from this study with the results of experimental visualization shows qualitative agreement.

Momentum and energy of a solitary wave interacting with a submerged semi-circular cylinder

2012 ◽  
Vol 708 ◽  
pp. 576-595 ◽  
Author(s):  
Christian A. Klettner ◽  
Ian Eames
Keyword(s):  
Free Surface ◽  
Circular Cylinder ◽  
Solitary Wave ◽  
Boundary Layers ◽  
Large Scale ◽  
Stagnation Points ◽  
Analytical Approximations ◽  
Short Period ◽  
Baseline Calculation ◽  
Viscous Boundary

AbstractThe interaction of a weakly viscous solitary wave with a submerged semi-circular cylinder was examined using high-resolution two-dimensional numerical calculations. Two simulations were carried out: (a) as a baseline calculation, the propagation of a solitary wave over uniform depth; and (b) a solitary wave interacting with a submerged semi-circular cylinder. Large-scale simulations were performed to resolve the viscous boundary layers on the free surface, bottom and around the obstacle. Integral measures such as momentum and energy are analysed and compared against analytical approximations. For uniform depth, the loss in momentum and energy arises from the traction caused by the finite length of the domain bottom and the dissipation which is predominantly within the bottom boundary layer, respectively. The force on the cylinder is composed of (form) drag, inertial and hydrostatic components, the last factor arising from gradients in the height of the free surface. Morison’s semi-empirical equation is shown to provide a leading-order description of the force on the semi-circular cylinder. These elevated rates of change (momentum and energy) return to uniform depth values after a short period of time, indicating a localized effect of the obstacle. To interpret the flow field, vorticity, streamline and second invariant of the velocity gradient tensor plots were used to highlight relative thickness of boundary layers, vorticity distribution throughout the domain and stagnation points in the flow.

scholarly journals Control of the motion of a circular cylinder in an ideal fluid using a source

2020 ◽  
Vol 30 (4) ◽  
pp. 604-617
Author(s):  
E.M. Artemova ◽  
E.V. Vetchanin
Keyword(s):  
Fixed Point ◽  
Circular Cylinder ◽  
Level Set ◽  
Ideal Fluid ◽  
Equations Of Motion ◽  
Energy Integral ◽  
Integral Conditions ◽  
Unstable Fixed Point ◽  
Constant Strength ◽  
Momentum Integral

The motion of a circular cylinder in an ideal fluid in the field of a fixed source is considered. It is shown that, when the source has constant strength, the system possesses a momentum integral and an energy integral. Conditions are found under which the equations of motion reduced to the level set of the momentum integral admit an unstable fixed point. This fixed point corresponds to circular motion of the cylinder about the source. A feedback is constructed which ensures stabilization of the above-mentioned fixed point by changing the strength of the source.

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