Hi I am trying to model nematic liquid crystal behaviour under an electric field.
To do this I solve the following PDE.
Where 
is the angle of the liquid crystals with respect to the x axis. The direction of the liquid crystal is represented by the vector 
. The main problem that I have is that for nematic liquid crystals n and -n are the same thing as such is periodic and only values between 0 and pi should be allowed. Is there a way to constrain the results to only be within this range.