CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Main CFD Forum (http://www.cfd-online.com/Forums/main/)
-   -   Wrong Result from Simulation...using Autodesk Project Falcon.. (http://www.cfd-online.com/Forums/main/113955-wrong-result-simulation-using-autodesk-project-falcon.html)

addy01 March 1, 2013 12:53

Wrong Result from Simulation...using Autodesk Project Falcon..
 
1 Attachment(s)
What is Fd stand for in FALCON result? And if it is drag force then why am i getting lower drag force via calculation by using same coefficient of drag as shown in falcon.I m getting Cd approx 1.22 on a block of 1 m^2 cross section at the speed of 10m/s. then how it is possible that drag force calculated by the falcon is 83.189 N?? (Attached Photo)
While I am using formula for drag force .5*Cd*(rheo)*A*V^2 then i am getting 74.725 N (assuming the density of air 1.225 kg/m^3)...plz help if u can its really important for my project...or suggest me any alternative way...

Thanks & Regards..
ADDY

grad@itu March 1, 2013 14:47

We cant say completely wrong solution, actually theoretically most of the time cfd dont give "exact" solutions.
And there is and error about %11 not %50 or something because of this you should try different mesh size and check the mesh quailty and later then you can change your flow model.

Try these things and see the changes.. may be you take more approximate solution. ;(%5 or something this is your decision actually)

RodriguezFatz March 4, 2013 04:20

You should not expect to get better results from simulations. Maybe for some special artificial cases, but not for general ones.

andy_ March 4, 2013 06:41

Quote:

Originally Posted by addy01 (Post 410910)
What is Fd stand for in FALCON result? And if it is drag force then why am i getting lower drag force via calculation by using same coefficient of drag as shown in falcon.I m getting Cd approx 1.22 on a block of 1 m^2 cross section at the speed of 10m/s. then how it is possible that drag force calculated by the falcon is 83.189 N?? (Attached Photo)
While I am using formula for drag force .5*Cd*(rheo)*A*V^2 then i am getting 74.725 N (assuming the density of air 1.225 kg/m^3)...plz help if u can its really important for my project...or suggest me any alternative way...

Thanks & Regards..
ADDY

This appears to be a question for FALCON support or perhaps reading the FALCON manual. It would be rather surprising if the software writes a derived value on the screen without explaining how that value is derived.


All times are GMT -4. The time now is 16:03.