Accurate Computational Fluid Dynamics CFD Simulations

Banner - Accurate Computational Fluid Dynamics CFD Simulations

In computational fluid dynamics (CFD) simulations accuracy is often very important, especially for drag and lift values. References [1-3] describe a CFD benchmark problem for time-dependent flow around a cylinder where the Reynolds number varies between 0<=Re<=100. The references contain very accurate reference values for the drag and lift coefficients, and pressure difference between the front and rear of the cylinder.


This benchmark problem has been simulated with FEATool with several grid and time step sizes. The results are shown in the table below.

Ldtt(cd_max)cd_maxt(cl_max)cl_maxdp(t=8)
10.05003.950003.044927.450000.10927-0.10132
10.02503.950003.045017.075000.16774-0.10960
10.01253.937503.045036.975000.18064-0.10309
20.05004.000003.074310.400001.45990-0.10323
20.02504.125003.071185.000000.60703-0.10315
20.01253.937502.951715.925000.47294-0.10948
30.05003.950002.949526.000000.34591-0.09935
30.02503.950002.949895.800000.44944-0.09830
30.01253.937502.950035.737500.47833-0.10821
40.05003.950002.950156.000000.34475-0.10268
40.02503.950002.950535.775000.44271-0.10175
40.01253.937502.950685.712500.47006-0.11057
Ref.3.936252.950925.692500.47835-0.11162


As can be seen the computed values on the finest grid and time step are very accurate and close to the reference solution. The time evolution of the lift coefficient is the most difficult quantity to capture correctly, but from the figure below the computed solution is again very close to the reference.


FEATool Multiphysics CFD Benchmark lift reference curve

The FEATool model script file to run the time-dependent cylinder benchmark can be found in the FEATool examples directory or from the link below. Note that it might take quite some time for the simulation to finish depending on the choice of grid and time step sizes.


FEATool Instationary Flow Around Cylinder CFD Model Tutorial


References

[1] Schaefer M, Turek S. Benchmark computations of laminar flow around a cylinder. In Flow Simulation with High-Performance Computers II, Notes on Numerical Fluid Dynamics, vol. 52. Vieweg, 1996; 547-566.

[2] John V. Reference values for drag and lift of a two-dimensional time-dependent flow around a cylinder. International Journal for Numerical Methods in Fluids 2004; 44:777-788.

[3] John V, Rang J. Adaptive time step control for the incompressible Navier–Stokes equations. Comput. Methods Appl. Mech. Engrg. 199 (2010) 514–524.

Category: cfd

Tags: benchmark validation

Published:

SHARE ON

Twitter LinkedIn Facebook Google+