In the previous sections, we have gradually built up a problem specification.
Putting it all together and adding a TITLE, it looks like this:
TITLE 'Heat flow around an Insulating blob'
VARIABLES
Phi { the temperature }
DEFINITIONS
K = 1 { default conductivity }
R = 0.5 { blob radius }
EQUATIONS
Div(-k*grad(phi)) = 0
BOUNDARIES
REGION 1 'box'
START(-1,-1)
VALUE(Phi)=0 LINE TO (1,-1)
NATURAL(Phi)=0 LINE TO (1,1)
VALUE(Phi)=1 LINE TO (-1,1)
NATURAL(Phi)=0 LINE TO CLOSE
REGION 2 'blob' { the embedded blob }
k = 0.001
START 'ring' (R,0)
ARC(CENTER=0,0) ANGLE=360 TO CLOSE
PLOTS
CONTOUR(Phi)
VECTOR(-k*grad(Phi))
ELEVATION(Phi) FROM (0,-1) to (0,1)
ELEVATION(Normal(-k*grad(Phi))) ON 'ring'
END
We have defined a complete and meaningful problem in twenty-three readable lines.
The output from this script looks like this:
