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= Abstract =
 
= Abstract =
We applied a Large Eddy Simulation as well as Particle Image Velocity experiments at the flow around a vertical cylinder on a flat rigid bed. The occurring flow structure (horseshoe vortex) reveals a high dynamic pattern with horizontal oscillations generating turbulent kinetic energy. The vortex is linked to the dynamics of a wall-parallel jet, which exerts highly amplified shear stress to the bottom plate. Due to this shear stress erosion can take place in case of sand-embedded bridge piers leading to scour.
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We applied Large Eddy Simulation as well as Particle Image Velocity experiments on the flow around a cylinder mounted vertically on a flat rigid plate. The the so-called horseshoe vortex system, which occurs in front of the cylinder an wraps around it, is highly dynamic and generates large turbulent kinetic energy. The dynamics of the horseshoe vortex itself is linked to the dynamics of a wall-parallel jet under the vortex, pointing in the upstream direction. This jet exerts highly amplified shear stress to the bottom plate.
This study followed a bilateral apporach by studying this flow configuration numerically as well as experimentally. Both data sets refer to the same set-up, but were acquired independently and are made accessible at the end of the section [[UFR 3-35 Evaluation|Evaluation]].
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This study follows a dual approach by studying this flow configuration numerically as well as experimentally. Both data sets refer to the same set-up, but were acquired independently and are made accessible at the end of the section [[UFR 3-35 Evaluation|Evaluation]].
  
The presented results show the time-averaged flow streamlines visualizing the main flow structure. The distribution of the c-shaped turbulent kinetic energy as well as its budget terms such as mean convection, production, transport, and dissipation are shown. Furthermore, selected profiles of the velocity components and the Reynolds stresses, as well as of the pressure coefficient and the friction coefficient are presented.  
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The results presented show the time-averaged streamlines visualizing the main flow structure. The distribution of the c-shaped turbulent kinetic energy and its budget terms such as mean convection, production, transport and dissipation are shown as well. Furthermore, selected profiles of the velocity components and the Reynolds stresses, the pressure coefficient and the friction coefficient are presented.  
  
In general, the numerical and experimental results do agree well with each other. However, slight deviations are visible such as the time-averaged postition of the vortex system. Therefore, we introduced an adjusted horizontal coordinate to account for this deviation and to compare the velocity profiles at the same (relative) positions in the flow with respect to the position of the vortex.
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In general, the numerical and experimental results do agree with each other. However, slight deviations are visible such as the time-averaged position of the vortex system. To ease the comparison of the velocity profiles at the same positions relative to the vortex system, we introduced an adjusted horizontal coordinate. The data presented below was evaluated at distinct horizontal positions in this adjusted coordinate system and is thus located at the same positions relative to the vortex in both numerical and experimental datasets.
  
  

Revision as of 16:48, 8 September 2019

Cylinder-wall junction flow

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Description

Test Case Studies

Evaluation

Best Practice Advice

References

Semi-confined Flows

Underlying Flow Regime 3-35

Abstract

We applied Large Eddy Simulation as well as Particle Image Velocity experiments on the flow around a cylinder mounted vertically on a flat rigid plate. The the so-called horseshoe vortex system, which occurs in front of the cylinder an wraps around it, is highly dynamic and generates large turbulent kinetic energy. The dynamics of the horseshoe vortex itself is linked to the dynamics of a wall-parallel jet under the vortex, pointing in the upstream direction. This jet exerts highly amplified shear stress to the bottom plate. This study follows a dual approach by studying this flow configuration numerically as well as experimentally. Both data sets refer to the same set-up, but were acquired independently and are made accessible at the end of the section Evaluation.

The results presented show the time-averaged streamlines visualizing the main flow structure. The distribution of the c-shaped turbulent kinetic energy and its budget terms such as mean convection, production, transport and dissipation are shown as well. Furthermore, selected profiles of the velocity components and the Reynolds stresses, the pressure coefficient and the friction coefficient are presented.

In general, the numerical and experimental results do agree with each other. However, slight deviations are visible such as the time-averaged position of the vortex system. To ease the comparison of the velocity profiles at the same positions relative to the vortex system, we introduced an adjusted horizontal coordinate. The data presented below was evaluated at distinct horizontal positions in this adjusted coordinate system and is thus located at the same positions relative to the vortex in both numerical and experimental datasets.




Contributed by: Ulrich Jenssen, Wolfgang Schanderl, Michael Manhart — Technical University Munich

Front Page

Description

Test Case Studies

Evaluation

Best Practice Advice

References


© copyright ERCOFTAC 2019