Electrostatics XML

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willsprocket
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Electrostatics XML

Post by willsprocket »

Does this actually do anything:

Code: Select all

        <Parameter Widget="Combo"> 
          <Name> Electric Field </Name>
          <Type> String </Type>
          <Item Type="Active"> <Name> None </Name> </Item>
          <Item> <Name> Computed </Name> </Item>
        </Parameter>
 
Thanks, Will
willsprocket
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Re: Electrostatics XML

Post by willsprocket »

Second question:

I tried to use the keyword Nominal Potential Difference and it generated this error:

Code: Select all

ERROR:: LoadInputFile:  Unknown specifier: [100]
ERROR:: LoadInputFile:  In section: [boundary condition 2]
ERROR:: LoadInputFile:  For property name:[nominal potential difference]
Last edited by willsprocket on 21 Jun 2022, 00:35, edited 1 time in total.
willsprocket
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Re: Electrostatics XML

Post by willsprocket »

BC for 1 that generates error:

Code: Select all

Boundary Condition 2
  Target Boundaries(1) = 1 
  Name = "BoundaryCondition 2"
  Layer Thickness = 4e-5
  Nominal Potential Difference = 100
  Layer Charge Density = 1e-6
  Electrode Potential = 100
  Electric Flux BC = True
  Layer Relative Permittivity = 9.6
End
Last edited by willsprocket on 21 Jun 2022, 00:38, edited 1 time in total.
willsprocket
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Re: Electrostatics XML

Post by willsprocket »

Test case plus my electrostatics xml. The inner sphere should see a reduction of the electric field based on the layer's relative permittivity.

The keyword is listed in the documentation for electrostatics (section 16) and thin oxide layers.
Attachments
electrostaticOxide.xml
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shelloxidetest.zip
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willsprocket
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Re: Electrostatics XML

Post by willsprocket »

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kevinarden
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Re: Electrostatics XML

Post by kevinarden »

It means it doesn't know the variable type it has to be declared

use

Nominal Potential Difference = Real 100
raback
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Re: Electrostatics XML

Post by raback »

willsprocket wrote: 20 Jun 2022, 18:57 Does this actually do anything:
...
I think it is related to this commit:

Code: Select all

commit 47efadd48459c0a12f7a39a5f7f197c2b6ab6bfd
Author: richb2k <75949649+richb2k@users.noreply.github.com>
Date:   Fri Mar 12 12:16:21 2021 -0600

    For the Electrokinetics tutorial, it was needed to add an entry
    in the Equation Block for 'Electric Field = Computed'.  Also,
    Free text input sections were added to Equation, Solver, and
    Boundary Conditions sections of electrostatics.xml
So it does nothing except with the electrokinetics stuff.

-Peter
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Re: Electrostatics XML

Post by raback »

Hi

Looking into this there may be some discrepancy with the documentation: I could not find reference to "nominal potential difference" in the code. The keyword "electrode potential", on the other hand, is used. Perhaps there was an idea to give a fixed potential difference for a Dirichlet condition but it makes little sense as it could be directly added to the Dirichlet value. I could not find any history on this and will remove it from the documentation. Or do you see any way to use it in conjunction of the BC?

The "potential difference" keyword may be given in Solver section is used to computed capacitance from the total energy. If not given the potential difference is defined by the min/max potentials in the system. Sometimes in crappy meshes this is different that the applied potential difference. Hence the optional keyword.

-Peter
willsprocket
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Re: Electrostatics XML

Post by willsprocket »

I thought that "Electrode Potential" was used since the oxide layer should change the field at the surface and it's an implied layer and not physical.

------

Further to Model 16 (Electrostatics) and modeling an oxide layer.

The documentation also says that the Electric Flux BC keyword needs to be set to True but that keyword is found only in Poisson-Boltzmann Equation (Model 25). Is that correct, does that mean that the equation needs to be added to the simulation? The Electric Flux BC keyword used solely with the Electrostatics model doesn't seem to affect the result.

I would expect that the oxide would reduce the electric field at the surface of the conductor, but that doesn't seem to be happening so there is something that I don't understand or implemented incorrectly.

Will
Rich_B
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Re: Electrostatics XML

Post by Rich_B »

Hello,

To answer your original question, the xml creates a combo drop box with two entries, None, and Computed. None is the default for the solver. Selecting Computed tells the sif generator to add a line 'Electric Field = Computed' to the Equation section of the sif file. The solver then will obey this command and compute the electric field.

There are similar examples of this combo drop box construction in other edf menus, search for 'Phase Change Model' in heatequation.xml to find one like this:
<Parameter Widget="Combo">
<Name> Phase Change Model </Name>
<Type> String </Type>
<Item Type="Active"> <Name> None </Name> </Item>
<Item> <Name> Spatial 1 </Name> </Item>
<Item> <Name> Spatial 2 </Name> </Item>
<Item> <Name> Temporal </Name> </Item>
<Whatis> One of: None, Spatial 1, Spatial 2 and Temporal. Note that when solidification is modelled, the enthalpy-temperature- and viscosity-temperature-curves must be defined in the material section. </Whatis>
Rich.
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