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Structure identification in pipe flow using proper orthogonal decomposition.
Leo H O Hellström1, Alexander J Smits2
1Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA lhellstr@princeton.edu.
Summary
Proper orthogonal decomposition reveals pressure aligns with large-scale turbulent motions in pipe flow. Low-pressure regions follow high-pressure regions in these energetic structures.
Area of Science:
- Fluid Dynamics
- Turbulence Research
- Computational Fluid Dynamics
Background:
- Turbulent pipe flow is a fundamental problem in fluid dynamics.
- Understanding energetic motions is crucial for developing accurate turbulence models.
- Direct numerical simulations (DNS) provide detailed flow field data.
Purpose of the Study:
- To investigate energetic motions in turbulent pipe flow using proper orthogonal decomposition (POD).
- To extend POD to include pressure information alongside velocity components.
- To analyze the relationship between pressure and large-scale turbulent structures.
Main Methods:
- Direct numerical simulations (DNS) of turbulent pipe flow at Reτ=685.
- Application of proper orthogonal decomposition (POD) to the velocity field.
- Extension of POD to incorporate the pressure field for each mode.
Main Results:
- The pressure component of POD modes aligns with the streamwise velocity component of large-scale motions.
- Positive pressure correlates with positive streamwise velocity, and negative pressure with negative streamwise velocity.
- Visualizations show structures with low-pressure downstream and high-pressure upstream regions, similar to large-scale, low-momentum motions.
Conclusions:
- Pressure plays a significant role in the dynamics of large-scale turbulent structures in pipe flow.
- The extended POD method effectively identifies pressure-velocity correlations in turbulent flows.
- Findings contribute to high-fidelity modeling of wall turbulence at high Reynolds numbers.
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