[luckyluke]

The periodic condition can be defined as follows:
sides
{
type cyclic;
value uniform (0 0 0);
}
The entry term 'value' confused me. What is the exact meaning of this term?

[henry]

The entry term 'value' gives the field value on the patch.

[luckyluke]

I use cyclic condition for 'Gamma' when I solve RT instability with interFoam.
sides
{
type cyclic;
value uniform 0;
}

Does the entry 'value' act as only an initial setting? After I run 'setGammaDamBreak', the value of Gamma of boundary 'sides' will be not zero,but determined by 'setGammaDamBreak'. Is it right?

[henry]

Of course it's only the initial value, did you really think all boundary condition values are fixed to the value given?

[luckyluke]

That is ok. ^_^. With your gamma*(1-gamma) and gamma differencing scheme, I have got beautiful 3D RT instability interface structure. If I delete the gamma*(1-gamma) term and apply only the GD scheme, the sharp interface will be lost, right? I am not very clear with the effect on sharp interface intruduced by gamma*(1-gamma) term. How does it compress the interface?

By the way, if I use wall condition on my 'sides' boundary,
sides
{
type gammaContactAngle;
theta0 90;
thetaA 90;
thetaR 90;
uTheta 0.01;
value uniform 0;
}
Then here how the 'value' entry affect the values on the patch? Will the gamma on the patch change when time goes?

[henry]

Why not find out for yourself, you will learn more that way and without consuming other peoples time.