The interaction of gravity current with a submerged circular cylinder

2004 ◽  
pp. 619-625
Author(s):  
K Mok ◽  
K Ieong ◽  
Harry Yeh
Keyword(s):  
Circular Cylinder ◽  
Gravity Current

Vortex shedding by a circular cylinder in lock-exchange density current 

2021 ◽  
Author(s):  
Ana M Ricardo ◽  
Giovanni Di Lollo ◽  
Moisés Brito ◽  
Claudia Adduce ◽  
Rui M.L. Ferreira
Keyword(s):  
Circular Cylinder ◽  
Fresh Water ◽  
Vortex Shedding ◽  
Gravity Current ◽  
Shear Instability ◽  
Density Current ◽  
Bluff Bodies ◽  
Density Currents ◽  
Ambient Fluid ◽  
Dense Fluid

<p>Flow around bluff bodies have been attracting the interest of the research community for more than a century. The physical mechanisms associated with the vortex shedding in the wake of bluff bodies is still of fundamental research interest. However, flow-structure interaction in density currents has not received enough attention. The transient nature of the interaction between the density driven flow and a stationary object constitutes the motivation for the present laboratory study aiming at investigating the vortex generation and fate on the wake of a circular cylinder in a density current.</p><p>The experiments were conducted in a horizontal and rectangular cross-section channel with 3.0 m long, 0.175 m wide and 0.4 m deep. The gravity current was generated using the classic lock-exchange configuration. A sliding stainless-steel gate with 1 mm thickness, sealed by PVC board glued in the sidewall, was positioned at 0.3 m from the left hand side of the channel. The experiment starts when the gate is suddenly removed, leaving the dense fluid to flow along the bottom of the channel, while the ambient fluid moves above in the opposite direction. The dense fluid consists in a mixture of fresh water and salt while the ambient fluid is a solution fresh water and ethanol (96%). The amount of salt and alcohol added in each mixture was determined in order to obtain a given density difference and to ensure the same refractive index in both fluids. Two different currents were tested with reduced gravity equal to 0.06 ms<sup>-2</sup> and 0.24 ms<sup>-2</sup>. For each test ten repetitions were carried out. Instantaneous velocity maps were acquired with a Particle Image Velocimetry system at 15 Hz. Polyamide seeding particles of density equal to 1.03 were added in both dense and ambient fluids.</p><p> The Reynolds number varied between 1500 and 4000. The results show that vortex shedding varies as the current reaches and overtakes the cylinder. Boundary layer detachment and shear instability is initiated shortly before the snout reaches the cylinder. A pattern of well-defined symmetrical vortexes is formed as a result of the initial shear instability. As the head of the current engulfs the cylinder, stronger turbulence diffusion contributes to reduce vortex coherence. Vortexes are smaller and detach sooner, while is not clear if shedding is alternate or simply random. The formation length is smaller than that of a steady flow with the same Re. When the back of the current passes, the formation length is increased and vortex shedding becomes periodical again. A striking feature is that the Von Kármán street is frequently symmetrical rather than exhibiting a pattern of alternate vortices.</p><p>This research was funded by national funds through Portuguese Foundation for Science and Technology (FCT) project PTDC/CTA-OHR/30561/2017 (WinTherface).</p>

Large Eddy Simulation of Gravity Current Flow Past a Circular Cylinder Using Immersed Boundary Method

2015 ◽  
Author(s):  
Jae Hwan Wang ◽  
Hyun Sik Yoon
Keyword(s):  
Circular Cylinder ◽  
Large Eddy Simulation ◽  
Gravity Current ◽  
Numerical Approach ◽  
Gravity Currents ◽  
Hydrodynamic Forces ◽  
Circular Cylinders ◽  
Immersed Boundary ◽  
Eddy Simulation ◽  
Large Eddy

We investigated the flow of gravity currents past circular cylinders above the smooth bed. In order to simulate the gravity current interacting with cylinder, large eddy simulation (LES) coupled with a direct forcing/fictitious domain (DF/FD) method was employed. The hydrodynamic forces induced by the gravity current on a circular cylinder and the flow features were investigated according to a gap distance from location below the cylinder to the bed and Reynolds number. When the gravity current encounters the circular cylinder, the maximum drag force occurs regardless of gap distance. In addition, Von Karman vortex shedding emerges behind the circular cylinder for larger gap distance. In this regard, the results can be divided into impact, transient and quasi-steady stages based on the characteristics of the hydrodynamic forces varying with time, which is consistent with previous observations. Consequently, our numerical approach well simulated the flow of gravity currents past circular cylinders in good agreement with those of previous studies.

Low Reynolds number flow around and heat transfer from a heated circular cylinder

2010 ◽  
Vol 1 (1-2) ◽  
pp. 15-20 ◽  
Author(s):  
B. Bolló
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Lift Coefficient ◽  
Reynolds Numbers ◽  
Low Reynolds Numbers ◽  
Reynolds Number Flow ◽  
Two Dimensional Flow ◽  
Number Flow ◽  
Low Reynolds ◽  
Increasing Temperature

Abstract The two-dimensional flow around a stationary heated circular cylinder at low Reynolds numbers of 50 < Re < 210 is investigated numerically using the FLUENT commercial software package. The dimensionless vortex shedding frequency (St) reduces with increasing temperature at a given Reynolds number. The effective temperature concept was used and St-Re data were successfully transformed to the St-Reeff curve. Comparisons include root-mean-square values of the lift coefficient and Nusselt number. The results agree well with available data in the literature.

Sign in / Sign up

Export Citation Format

Share Document