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-   -   Drag and lift forces monitors (https://www.cfd-online.com/Forums/fluent/138472-drag-lift-forces-monitors.html)

Isitv2A July 4, 2014 10:03

Drag and lift forces monitors
 
What fluent calculate when i ask him to monitors drag and lift forces on my cylinder in a flow ?

I was thinking that it was the coefficient but i got high value betwen -15 ...15 my result are sinusoidale like said theory .

Isitv2A July 7, 2014 03:24

can anyone tell me if fluent compute the force or the coefficient ?

thanks you

Traction July 7, 2014 05:29

If you set up the reference area in the Reference Values Tab correctly Fluent will show you coefficients.

Isitv2A July 7, 2014 08:06

hi traction when i am on lift/drag monitor tab i have to select a wall zone but i don't know wich one is the correct one i got "wall 5" and "wall 5 shadow they correspond to the interface between my cylinder and the water !

my geometry is simple i got a cylinder and around ar square of water . i created for water one face as "amont" (input velocity) , an other "aval " as output pressure . 4 face " wall" as (symetry) . For my cylinder have 3 face "top" (wall) , "bot" (wall) and "interface" but when i go from meshing to fluent , i got (wall15 , wall14 , wall 5 , wall 5shadow , interface_src , inteface_trg ) in adition of the rest in the liste of zone in boundary condition .

when i try to display (wall (14/15/5/5shadow nothing appear) for interface(src et trg i got the wall of my cylinder !

can you explain me wath are the wall(14 15 5 5 shadow )?


thanks !

Traction July 7, 2014 08:23

ok. i misunderstood.
when you are in the force reports tab fluent will show you forces.

fluent should also show your geometry when you setup the display tab correctly. i have no idea why this doesn´t work for you.

which mesher do you use ? do you create named parts while meshing ?

Isitv2A July 7, 2014 08:35

i don't really know i just use the one Ansys give me

name meshing with a logo (red circle with white M ) not really precise but i think u know it if u use Ansys .

I have named all my face of my part during meshing .

Isitv2A July 7, 2014 08:39

So fluent plot the force on my wall in Newton . Is that correct ?

Traction July 7, 2014 09:08

During calculation Fluent plots coefficients. When your calculation is finished Fluent shows forces when you use the Results / Force Reports Tabs.

If you use SI units the forces are in Newton. Remember that Fluent assumes physical dimensions of your geometry in meters. Regardless of whether your mesh is build in millimeters or something else.

Isitv2A July 7, 2014 11:02

Thanks .

well i will work on it because , what fluent plot is not what is expected from theories .


And i will see on CFX-post the force report thanks


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