[ff3d-users] Applying Boundary conditions

[Juzar Thingna]

Hello Everyone,
Below is my POV file

1 union{
2 box{<0,0,0>,<1000000,1,1000000>}
3 box {<250000,1,450000>,<350000,10000001,550000>}
4 box {<740000,1,495000>,<750000,10000002,505000>}
5 pigment {color rgb <1,0,0>}
6 }

I have the following questions.
1) I need to apply Dirichlet Boundary conditions to face ymax of Box in line
3 and a different Dirichlet condition to face ymax of Box in line 4. Is it
possible in ff3d to apply boundary conditions by specifying a plane by
co-ordinates rather than ymax. If so how can this be done? Box in line 4 is
slightly larger than Box in line 3. Also if I specify the BC at ymax does it
apply the condition on the global ymax of the geometry ( in this case it
would be y=10000002) or does it apply it to the local ymax at each point of
the geometry?

2) As you can see my numbers are very large so I'll need a very fine mesh.
Will such numbers cause any numerical errors while transferring from POV to
ff3d?

Regards,
Juzar Thingna
Center for Computation Science and Engineering
National University of Singapore

[Stephane Del Pino]

Hello again.

Post by Juzar Thingna
Hello Everyone,
Below is my POV file
1 union{
2 box{<0,0,0>,<1000000,1,1000000>}
3 box {<250000,1,450000>,<350000,10000001,550000>}
4 box {<740000,1,495000>,<750000,10000002,505000>}
5 pigment {color rgb <1,0,0>}
6 }
I have the following questions.
1) I need to apply Dirichlet Boundary conditions to face ymax of Box in
line 3 and a different Dirichlet condition to face ymax of Box in line 4.
Is it possible in ff3d to apply boundary conditions by specifying a plane
by co-ordinates rather than ymax. If so how can this be done? Box in line
4 is slightly larger than Box in line 3. Also if I specify the BC at ymax
does it apply the condition on the global ymax of the geometry ( in this
case it would be y=10000002) or does it apply it to the local ymax at each
point of the geometry?

It does not work like that in ff3d. xmin, ymin and zmin are related to the
computational mesh : not to the computational domain.

But you can define different objects of different colors (pigment {color rgb
<r,g,b>}) then apply different BC on each color as it is defined in the user
documentation.

Post by Juzar Thingna
2) As you can see my numbers are very large so I'll need a very fine mesh.
Will such numbers cause any numerical errors while transferring from POV to
ff3d?

Not in the translation but for the numerical resolution of the linear system.

Best regards,
Stéphane.