scholarly journals EFFECT OF THE SPANWISE DISCRETISATION ON TURBULENT FLOW PAST A CIRCULAR CYLINDER

2021 ◽  
Vol 158 (A1) ◽  
Author(s):  
S Kim ◽  
P A Wilson ◽  
Z Chen
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Flow Field ◽  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Three Dimensional ◽  
Scale Model ◽  
Spatial Density ◽  
Eddy Simulation ◽  
Large Eddy

The effect of the spanwise discretisation on numerical calculations of the turbulent flow around a circular cylinder is systematically assessed at a subcritical Reynolds number of 10000 in the frame of three-dimensional large-eddy simulation. The eddy-viscosity k-equation subgrid scale model is implemented to evaluate unsteady turbulent flow field. Large-eddy simulation is known to be a reliable method to resolve such a challenging flow field, however, the high computational efforts restrict to low Reynolds number flow or two-dimensional calculations. Therefore, minimum spatial density in the spanwise direction or cylinder axis direction needs to be carefully evaluated in order to reduce high computational resources. In the present study, the influence of the spanwise resolutions to satisfactorily represent three- dimensional complex flow features is discussed in detail and minimum spatial density for high Reynolds flow is suggested.

Application of Large Eddy Simulation to an Oscillating Flow Past a Circular Cylinder

1997 ◽  
Vol 119 (3) ◽  
pp. 519-525 ◽  
Author(s):  
Xiyun Lu ◽  
Charles Dalton ◽  
Jianfeng Zhang
Keyword(s):  
Circular Cylinder ◽  
Large Eddy Simulation ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Scale Model ◽  
Oscillating Flows ◽  
Step Method ◽  
Fractional Step Method ◽  
Eddy Simulation ◽  
Large Eddy

Three-dimensional sinusoidally oscillating flows around a circular cylinder are investigated by using a viscous flow method (VFM) and a large eddy simulation (LES). A second-order accurate in time fractional step method and a combined finite-difference/spectral approximation are employed to solve the filtered incompressible Navier-Stokes equations. To demonstrate the viability and accuracy of the method, we calculate two cases of steady approach, flows at Reynolds numbers Re = 100 using VFM and Re = 104 using LES. For sinusoidally oscillating flows at β = 1035, the flow is 2D for KC< 0.5, 3D for 0.5 < KC < 2, and turbulent for KC > 2. For KC = 0.5, 0.8 and 1, the flow is calculated using VFM. For KC = 2, 3, 4, 5, 8 and 10, we have simulated the flow using LES with the Smagorinsky subgrid scale model. The drag and inertia coefficients are calculated from the in-line force acting on the cylinder and are in very good agreement with experimental data.

Application of Large Eddy Simulation to Flow Past a Circular Cylinder

1997 ◽  
Vol 119 (4) ◽  
pp. 219-225 ◽  
Author(s):  
X. Lu ◽  
C. Dalton ◽  
J. Zhang
Keyword(s):  
Circular Cylinder ◽  
Large Eddy Simulation ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Scale Model ◽  
Step Method ◽  
Fractional Step Method ◽  
Eddy Simulation ◽  
Large Eddy

A steady approach flow around a circular cylinder is investigated by using a large eddy simulation (LES) with the Smagorinsky subgrid-scale model. A second-order accurate in time fractional-step method and a combined finite-difference/spectral approximation are employed to solve the filtered three-dimensional incompressible Navier-Stokes equations. To demonstrate the viability and accuracy of the method, we present results at Reynolds numbers of 100, 3 × 103, 2 × 104, and 4.42 × 104. At Re = 100, the physical flow is two-dimensional and the calculation is done without use of the LES method. For the higher values of Re, the flow in the wake is three-dimensional and turbulent and the LES method is necessary to describe the flow accurately. Calculated values of lift and drag coefficients and Strouhal number are in good agreement with the experimentally determined values at all of the Reynolds numbers for which calculation was done.

Large eddy simulation study of turbulent flow around smooth and rough domes

2013 ◽  
Vol 227 (12) ◽  
pp. 2686-2700 ◽  
Author(s):  
N Kharoua ◽  
L Khezzar
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Flow Behavior ◽  
Pressure Coefficient ◽  
Horseshoe Vortex ◽  
Scale Model ◽  
Stream Velocity ◽  
Mean Velocity ◽  
Eddy Simulation ◽  
Large Eddy

Large eddy simulation of turbulent flow around smooth and rough hemispherical domes was conducted. The roughness of the rough dome was generated by a special approach using quadrilateral solid blocks placed alternately on the dome surface. It was shown that this approach is capable of generating the roughness effect with a relative success. The subgrid-scale model based on the transport of the subgrid turbulent kinetic energy was used to account for the small scales effect not resolved by large eddy simulation. The turbulent flow was simulated at a subcritical Reynolds number based on the approach free stream velocity, air properties, and dome diameter of 1.4 × 105. Profiles of mean pressure coefficient, mean velocity, and its root mean square were predicted with good accuracy. The comparison between the two domes showed different flow behavior around them. A flattened horseshoe vortex was observed to develop around the rough dome at larger distance compared with the smooth dome. The separation phenomenon occurs before the apex of the rough dome while for the smooth dome it is shifted forward. The turbulence-affected region in the wake was larger for the rough dome.

scholarly journals Optimization of the Turbulence Model on Numerical Simulations of Flow Field within a Hydrocyclone

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Yan Xu ◽  
Zunce Wang ◽  
Lin Ke ◽  
Sen Li ◽  
Jinglong Zhang
Keyword(s):  
Flow Field ◽  
Large Eddy Simulation ◽  
Cross Sections ◽  
Three Dimensional ◽  
Reynolds Stress Model ◽  
Computational Grids ◽  
Test Results ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Simulation Results

Reynolds Stress Model and Large Eddy Simulation are used to respectively perform numerical simulation for the flow field of a hydrocyclone. The three-dimensional hexahedral computational grids were generated. Turbulence intensity, vorticity, and the velocity distribution of different cross sections were gained. The velocity simulation results were compared with the LDV test results, and the results indicated that Large Eddy Simulation was more close to LDV experimental data. Large Eddy Simulation was a relatively appropriate method for simulation of flow field within a hydrocyclone.

Investigation of Fully Developed Turbulent Flow in a Straight Duct With Large Eddy Simulation

1994 ◽  
Vol 116 (4) ◽  
pp. 677-684 ◽  
Author(s):  
M. D. Su ◽  
R. Friedrich
Keyword(s):  
Reynolds Number ◽  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Secondary Flow ◽  
Initial Conditions ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Fully Developed Turbulent Flow ◽  
High Reynolds ◽  
Straight Duct

Large eddy simulations have been performed in straight ducts with square cross section at a global Reynolds number of 49,000 in order to predict the complicated mean and instantaneous flow involving turbulence-driven secondary motion. Isotropic grid systems were used with spatial resolutions of 256 * 642. The secondary flow not only turned out to develop extremely slowly from its initial conditions but also to require fairly high resolution. The obtained statistical results are compared with measurements. These results show that the large eddy simulation (LES) is a powerful approach to simulate the complex turbulence flow with high Reynolds number. Streaklines of fluid particles in the duct show the secondary flow clearly. The database obtained with LES is used to examine a statistical turbulence model and describe the turbulent vortex structure in the fully developed turbulent flow in a straight duct.

Large Eddy Simulation of Flow around a Cylinder at Re=3900 Using a CFD Code

2011 ◽  
Vol 94-96 ◽  
pp. 1707-1710 ◽  
Author(s):  
Yao Zhen Li
Keyword(s):  
Large Eddy Simulation ◽  
Three Dimensional ◽  
Scale Model ◽  
Subgrid Scale ◽  
Flow Around A Cylinder ◽  
Cpu Time ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Subgrid Scale Model ◽  
Better Than

Flow over circular cylinder at Reynolds number 3900 is studied numerically using the technique of Large Eddy Simulation .As a result, strong three-dimensional characteristics are revealed in flow around a cylinder at Re=3900. As spanwise and streamwise mesh refinement is done respectively, result improves similarly. But the CPU time consumed is too much when refinement meshes are used. Also the simulation result with Smagorinsky subgrid-scale model is investigated to be better than subgrid-scale k model.

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