How Do You Numerically Solve Coupled PDEs with Continuity Constraints?

[keyns]

I'm new, hi all.

I have two coupled equations, one of which is continuity. Basically, my problem comes down to the following system:

(1) u=f(v) (similarly, v=g(u). Here, u and v are the components of a vector field, ie u=u(x,y) and v=v(x,y).

(2) Continuity: \nabla \cdot \textbf{u} = 0 or u_{x}+v_{y}=0

From here, I can find the following expressions

u_{x} = -g_{y} \left( u \right)
v_{y} = -f_{x} \left( v \right)

Which I think leaves an equation of the form G \left( u,u_{x},u_{y} \right)=0 and F \left( v,v_{x},v_{y} \right)=0

It seems to me my original problem has two variables and I have two equations. I think this should be solvable, but I don't know how. Any help please? Thanks in advance!

--edit-- p.s. I'm looking for a numerical (discrete) solution.

 

[Mute]

I'm new, hi all.

I have two coupled equations, one of which is continuity. Basically, my problem comes down to the following system:

(1) u=f(v) (similarly, v=g(u). Here, u and v are the components of a vector field, ie u=u(x,y) and v=v(x,y).

If u = f(v) and v = g(u), don't you just have a (possibly nonlinear) system of equations to solve for v and u? What is the continuity condition (2) for? Do you get more than one solution by solving (1) and you need (2) to choose a solution of interest?

 

[keyns]

If u = f(v) and v = g(u), don't you just have a (possibly nonlinear) system of equations to solve for v and u? What is the continuity condition (2) for? Do you get more than one solution by solving (1) and you need (2) to choose a solution of interest?

Actually I have only one relation for u and v that I can write it as u(v) or v(u). Sorry for the confusion. Otherwise you would be right. To clarify my equations:

(1) A relation for u and v (if I have u, I have v and vice versa)
(2) A relation for u_{x} and v_{y} (if I have u_{x}, I have v_{y} and vice versa

--edit-- Which then, after some rewriting, leads to two ODE's G and F as stated before. I just don't know how to solve those.