Learning Forum

[w d]

using the default report definitions in fluent (shown below), testing an ahmed body i'm getting a cl of ~0.34, very close to experimental,

However if you put the lift force (~181N) and the top projected reference area (3.25m^2) and velocity (30m/s) to work out the lift coef, it comes out at about 0.1.

If you use the front projected area (0.988m^2) instead you get cl ~0.33, which seems to mean its using the front projected area to calculate lift coefficant? shouldn't it use top projected area? and if yes why is the cl so far off experimental?

(z axis is forward, not x)

 

[Federico]

Fluent uses Reference Values, entered in the Physics tab, which has 1m^2 as default, to calculate Cl and Cd.

You can change this to your desired value.

[Sunil Lilhare]

Hello, the coefficient calculations are affected by the reference values. Therefore, please ensure that the refence values entered are correct. For Cl calculation, enter the correct reference values like projected area in area field and then calculate it using report definitions.

To know more about the reference values, please have a look at the link of Ansys Fluent's User Guide given below.

40.12. Reference Values (ansys.com)

If you are unable to access above link then please have a look at the link given below which shows how to access the Ansys Online Help.

How to access the ANSYS Online Help