Viscosity in different subdomains

Main Forum Old-Forum - do not post here
1

Hello everyone,

I have divided my domain into 2 sub-domains sucsessfully following the documentation.
With single domain I used to set a single value to a viscosity but now I want to define different viscosities in
different subdomains, anyone knows how to set this ?

Thanks in advance.

2

Hi,

you can use domain-wise coefficient functions by using as list of values/functions as argument of the CoefficientFunction.

from netgen.geom2d import SplineGeometry
geo = SplineGeometry()
geo.AddRectangle((0,0),(1,1),leftdomain=1,rightdomain=0)
geo.AddRectangle((0.3,0.3),(0.7,0.7),leftdomain=2,rightdomain=1)
from ngsolve import *
mesh = Mesh(geo.GenerateMesh(maxh=0.2))
Draw(mesh)
Draw(CoefficientFunction([1,2]),mesh,'cf')

I hope that’s what you are looking for.

Best,
Christoph