CFD Online Discussion Forums - How to calculate and write out transient drag / lift coefficient in OpenFOAM 2.2.1?

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How to calculate and write out transient drag / lift coefficient in OpenFOAM 2.2.1?

It seems that a keyword functions containing forces and forcesCoeffs should be added at the end of controlDict.

Is there any tutorial to give a typical example, and what's the meaning of each entry.

These two are founded on OpenFOAM forum.

Code:

functions

{ forces

{

type forceCoeffs;

functionObjectLibs ( "libforces.so" );

outputControl timeStep;

outputInterval 1;

patches (profile_wall)

pName p;

UName U;

log true;

rhoInf 1.225;

CofR ( 0 0 0 );

liftDir ( 0 1 0 );

dragDir (1 0 0 );

pitchAxis ( 0 0 1 );

magUInf 100.0;

lRef 0.1254;

Aref 0.01292;

}

}

Code:

functions

{

forces

{

type forces;

functionObjectLibs ( "libforces.so" ); // lib to load

outputControl timeStep;

outputInterval 1;

patches

(

wall // change to your patch name

);

// name of fields

pName p;

UName U;

log true; // dump to file

rhoInf 1025;

CofR ( 0 0 0 );

}

forcesCoeffs

{

type forceCoeffs;

functionObjectLibs ( "libforces.so" ); // lib to load

outputControl timeStep;

outputInterval 1;

patches

(

wall // change to your patch name

);

// name of fields

pName p;

UName U;

log true; // dump to file

rhoInf 1025;

CofR ( 0 0 0 );

liftDir ( 0 1 0 );

dragDir ( 1 0 0 );

pitchAxis ( 0 0 0 );

magUInf 7.30;

lRef 0.305;

Aref 0.001525;

}

}

Thanks in advance.

execFlowFunctionObjects

i use execFlowFunctionObjects but i have this problem
Time = 0.0008
Reading phi
Reading U
Reading p
Selecting incompressible transport model Newtonian
Selecting LES turbulence model oneEqEddy
Selecting LES delta type smooth
Selecting LES delta type cubeRootVol
--> FOAM Warning :
From function cubeRootVolDelta::calcDelta()
in file cubeRootVolDelta/cubeRootVolDelta.C at line 52
Case is 2D, LES is not strictly applicable

There's in OF a function object that allows to evaluate lift and drag?...not coefficient.
Thank's in advance for your attention

Hi fluxent

type this inside functions () in controlDict

forces
{
type forces;
functionObjectLibs ("libforces.so");
patches (//patches of wall you are calculating);
pName p;
UName U;
rhoName rhoInf;//for incompressible
rhoInf 1.2; // Reference density, fluid
CofR (0 0 0); // Origin for moment calculations
outputControl timeStep;
outputInterval 1;
}

You can find in tutorials/incompressible/pimpleDyMFoam/wingMotion/

Hi er_trebbia

can this give force coefficients or required forces to find Cl, Cd?

Thank you