Tandem Cylinder Simulations using the Method of Your Choice Some Body Affiliated Somewhere

Outline Objectives Numerical Method Flow Conditions Grids Results Computational Resources Observations 2

Objectives State any objectives such as testing numerical method, turbulence model, grid convergence, etc 3

4 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

5 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) 6

Results: Time step (in seconds) Number of time steps run (total and for sampling) Shedding frequency in Hz Time-averaged Drag (C D = f D /(D 0.5   |V o | 2 ) where f D 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 Cp rms after every 5000 time steps) 7

8 Surface Pressure UpstreamDownstream

9 RMS of Surface Pressure UpstreamDownstream

10 Mean Velocity Along y/D =0 Gap Region Aft of Downstream Cylinder

11 Surface Pressure Spectra Upstream,  = 135 o Downstream,  = 45 o 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 12

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 13

14 OPTIONAL

15 Surface Pressure Correlation Spanwise row of sensors at  =135 deg Upstream Downstream zz

16 Surface Pressure Coherence Spanwise row of sensors at  =135 deg Coherence at shedding frequency = 178 Hz Upstream Downstream zz

17 2D TKE 1/2 ( u' u' + v' v' + w' w' )/)/ V o 2 Gap Region Aft of Downstream Cylinder

18 2D TKE 1/2 ( u' u' + v' v' + w' w' )/)/ V o 2 along y/D =0 Gap Region Aft of Downstream Cylinder

19 2D TKE Gap Region, x/D =1.5Aft of Downstream Cylinder, x/D =4.45 1/2 ( u' u' + v' v' + w' w' )/)/ V o 2

20 Acoustic Radiation Spectra Significant peaks at harmonics