Learning Forum

[gaurav_shrivas15]

I want to calculate coefficeint of drag (Cd) using fluent; for the flow over cylinder in 2-dimensional domain:
Dia of cylinder= 0.1 m
Re=2x10^4

what Reference values should I used in fluent to find the Cd as defaults values are 1 for area,depth and length.
Area=?
density=1.225
Depth=?
Length=?
Velocity=2.93
Viscosity=1.7894e-05

When I calculated Cd using Report>Forces> cylinder wall>coefficient of drag. the results are not matched with available experimental results

[Federico Alzamora Previtali]

Assuming that your mesh is fine and solution has converged sufficiently, your Cd will depend on those reference values that you have defined. I would imagine that the experimental results that you mention would have their corresponding values documented. 

[gaurav_shrivas15]

hi federico,

my cd value is coming 0.78 where in research paper it is around 1.2 for  Re=2x10^4.

this value coming when i am giving reference value as follows

Area=0.1 (as diameter)
density=1.225
Depth=1
Length=1
Velocity=2.93
Viscosity=1.7894e-05

can you give any suggestion so I can reduce my error?

[Federico Alzamora Previtali]

I assume you have set the same values as your upstream conditions (velocity and density). How many iterations have you run? Has your solution converged? Can you show a screenshot of your residuals and pressure field?