Tandem Cylinder Simulationsusing the Method of Your Choice
Some BodyAffiliated Somewhere
Outline
• Objectives• Numerical Method• Flow Conditions• Grids• Results• Computational Resources• Observations
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Objectives
• State any objectives such as testing numerical method, turbulence model, grid convergence, etc
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Numerical Method
• Equations solved– Unsteady Reynolds-averaged Navier-Stokes (URANS) equations– Turbulence equations
• Spatial and temporal discretizations– Type of scheme (FD, FV, etc)– Design accuracy– Unique features of implementation
• Boundary Conditions
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Flow Conditions in Simulations
• Re = 166,000 based on D• Turbulence model run fully turbulent• Surface roughness strip placed at = 50 deg.
• M = 0.128
Grids
• Grid type (block-structured, unstructured, Cartesian)• # of Nodes or cells or …• Extent of grid (in plane and spanwise directions)
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Results:• Time step (in seconds)• Number of time steps run (total and for sampling)• Shedding frequency in Hz
• Time-averaged Drag (CD = fD/(D 0.5 |Vo|2) where fD is the force per unit span in the drag or streamwise direction, D = cylinder diameter) on front and rear cylinders
• Convergence information (e.g. history of Cprms after every 5000 time steps)
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Surface Pressure
Upstream Downstream
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RMS of Surface Pressure
Upstream Downstream
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Mean Velocity
• Along y/D=0
Gap Region Aft of Downstream
Cylinder
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Surface Pressure Spectra
Upstream, = 135o Downstream, = 45o
• Power Spectral Density
Computational Resources
• Computer hardware– CPU (type and number used)– Interconnect
• Resources– CPU (or wall clock) Time / time step
• # of time steps in simulation
– CPU (or wall clock) Time / 1 sec of simulation time• # of time steps needed for 1 sec of simulation time
– Memory used• Per cpu
• Total
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Observations
• What did you learn?– Computational challenges– New insights into the physics– Assessment of state-of-the-art based on your simulation
for the problem category of interest– Benchmark deficiencies– Recommendations for follow-on efforts
• Additional measurements
• Desired additions/modifications to problem statement
• Procedures for computations or measurements
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OPTIONAL
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Surface Pressure Correlation
• Spanwise row of sensors at =135 deg
Upstream Downstream
z
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Surface Pressure Coherence
• Spanwise row of sensors at =135 deg• Coherence at shedding frequency = 178 Hz
Upstream Downstream
z
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2D TKE
• 1/2 (u' u' + v' v' + w' w')/)/Vo2
Gap Region Aft of Downstream
Cylinder
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2D TKE• 1/2 (u' u' + v' v' + w' w')/)/Vo
2 along y/D=0
Gap Region Aft of Downstream
Cylinder
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2D TKE
Gap Region, x/D=1.5 Aft of Downstream
Cylinder, x/D=4.45
• 1/2 (u' u' + v' v' + w' w')/)/Vo2
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Acoustic Radiation
Spectra
• Significant peaks at harmonics
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