Sample Problems > Usage > Mesh_Control > mesh

{ MESH_SPACING.PDE

This example demonstrates the use of the MESH_SPACING parameter to

control mesh density.

A global density function is defined as a Gaussian distribution returning

1 unit mesh spacing at the center, falling to 0.018 at the corners.

This global distribution is overridden by a regional definition of

0.02 mesh spacing in a central region.

}

title 'Cell Size Control'

variables

definitions

k = 1

u0 = 1-x^2-y^2

s = 2*3/4+5*2/4

mesh_spacing = exp(-2*(x^2+y^2))

b = 0.1

c = 0.02

equations

u : div(K*grad(u)) +s = 0

boundaries

Region 1

start(-1,-1)

value(u)=u0

line to (1,-1) to (1,1) to (-1,1) to close

Region 2

mesh_spacing = c

start(-b,-b)

line to (b,-b) to (b,b) to (-b,b) to close

plots

grid(x,y)

contour(u)

end