Solving four coupled differential equations

Hi,

There's an energy equation I need to minimize. This equation is the first equation on this page: www.ee.ucl.ac.uk/~rjames/modelling/constant-order/oned/

However if you follow that page then you realize that energy minimization problem ends up being four linear differential equations to solve. (The 7th set of equations on that page.)

Now, I can do this in Matlab, indeed that link above does it for the 1D case in Matlab. Now I want to get COMSOL to solve these four differential equations. I see that I can go New > 2D > Global ODEs and DAEs > Global Equation, and I can enter differential equation here, but this is a differential equation of one variable, f(u,ut,utt,t), not a set of coupled differential equations. How do I enter four coupled differential equations and have matlab solve them on some mesh?

Is there some tutorial online for how to solve coupled differential equations on 2D or 3D meshes? I fail to find one.

Thanks.

P.S. if you are interested, I'm trying to solve the "director" distribution in a liquid crystal (LC) sandwich.
"Director" is the unit vector that describes which direction the LC molecules point at any given point.
By "sandwich" I mean, glass-LC-glass, and I'm drawing a 2D slice through this and trying to solve the director distribution at each mesh point.