TITLE	'Heat flow around an Insulating blob'
SELECT
	Bold = On
VARIABLES
	U				{ the temperature }
DEFINITIONS
	k = 1		{ default conductivity }
	r = 0.5		{ blob radius }
EQUATIONS
	dxx(k*U) + dyy(k*U) = 0
BOUNDARIES
	REGION 1
		START (-1,-1)
			VALUE(U) = 0		LINE TO (1,-1)
			NATURAL(U) = 0	LINE TO (1,1)
			VALUE(U) = 100	LINE TO (-1,1)
			NATURAL(U) = 0	LINE TO CLOSE
	REGION 2	{ the embedded blob }
		k = 0.001
		START 'ring' (r,0)
			ARC(CENTER=0,0) ANGLE=360 TO CLOSE
PLOTS
	GRID(x,y)
	CONTOUR(U)
	VECTOR(-k*grad(U))
	ELEVATION(U) FROM (0,-1) TO (0,1)
	ELEVATION(U) ON 'ring'
END