Defining a subdomain with constant properties

[AmbroiseJuston]

I need to define a type of subdomain that acts as a region of constant properties that is not affected by the kernals. In the picture i have attached it shows what i am looking to do. Currently I am using the RndBoundingBoxIC function to crease the regions of randomized values withing my specified range. What i want add is a region at the top and bottom, in a similar way to how RndBoundingBoxIC works.

My question is it possible to stack RndBoundingBoxIC or is there a way initialize the IC as shown in the figure i have sent. It is also important that the region shown in red/blue in the figure is the same with and without the top and bottom pieces so to compare the effects. Those regions are to act as a type of electrical terminal, where in this case c is conductivity.

If it possible to make it that the c=1 region is not effected by any of the physics of the simulation and stays at c = 1 for all time "t" then that would ne even more useful

Example code of how i am defining the ICs without the top and bottom c=1 regions:

[./concentrationIC]
type = RndBoundingBoxIC
variable = c
x1 = 10
y1 = 0
x2 = 30
y2 = 10
mx_invalue = 1
mn_invalue = 0
mx_outvalue = 0.3
mn_outvalue = 0.0
[../]

[GiudGiud]

Hello

So are you planning to solve equations on these domains?

You can define these simple domains using the ParsedGenerateSubdoamin for example, a mesh generator that goes in your mesh block

[AmbroiseJuston]

Yes ideally i would like to solve the same equations as the central (red/blue) region. I did notice the ParsedGenerateSubdoamin function but my main question is how i would then create the ICs for this subdomain as shown in the figure. To my understanding ParsedGenerateSubdoamin only defines the mesh in those regions unless the "constant_expressions" parameter is what takes care of thus. Will RndBoundingBoxIC override the ICs of that subdomain? How am I able to create the regions of difference ICs as shown in the figure?

As a secondary question will the inclusion of this subdomain then influence the distribution of the random values from RndBoundingBoxIC? Idealy i would like to compare the solutions with an without the top and bottom regions.

[GiudGiud]

ICs for this subdomain as shown in the figure

ICs can be block-restricted using the block parameter.

Will RndBoundingBoxIC override the ICs of that subdomain? How am I able to create the regions of difference ICs as shown in the figure?

If it supports block restrictions, then no it should not as long as its block restriction does not include the other subdomains

How am I able to create the regions of difference ICs as shown in the figure?

multiple ICs objects with different block restrictions

then influence the distribution of the random values from RndBoundingBoxIC?

good question. I dont imagine so but please check

[AmbroiseJuston]

Thank you very much. I will double check this randomized value. I guess i must have missed the block restriction part of the ICs so thank you and i apologize for the trouble.

On the subject of randomized ICs, do you know what nodes it propagates to first? does it go through all x, then all y, then all z or does it follow a different assignment priority for seeded randomized values?

[GiudGiud]

that depends on the ordering of the nodes in the mesh. you can look at the id field in paraview to see how your mesh is ordered

[AmbroiseJuston]

Thank you, i will look at them. One last part. If i wanted the id of the mesh within the central region to remain constant is there a way to edit the id field? Is the id field numbering based on spacial position or when it is generated?

[GiudGiud]

One last part. If i wanted the id of the mesh within the central region to remain constant is there a way to edit the id field?

the element and node ids cannot be kept constant. However you can use subdomains or extra-element-integer-ids to label a certain area in your mesh. Subdomains can be added from any meshing tools. EEIDs can be added to exodus files but you ll need to set an extra parameter in the FIleMeshGenerator to read them. Then your objects can be set to have specific behavior for a certain value of the subdomain or the EEID

Is the id field numbering based on spacial position or when it is generated?

It's determined at generation time, when elements are added to the mesh they are numbered