Default Settings of Particle Dynamics

[willsprocket]

Where can I find the default settings of the keywords for Particle Dynamics (Ch 35)?
https://www.nic.funet.fi/pub/sci/physic ... Manual.pdf


Additionally, How do I reference the electric field for the following keywords:

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Velocity Condition Variable Name String
Name of the field which determines the fixed velocity conditions of the particles.
Coordinate Condition Variable Name String
Name of the field which determines the fixed coordinate conditions of the particles.

I assume the next one is just "Potential"

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Potential Variable Name String
Name of the variable if electrostatic potential is present.

Thanks, Will

[kevinarden]

There doesn't appear to be default settings, didn't see any in the source code and generally the manual would say if there was a default

Potential Variable Name String
This keyword is used to specify the name of the underlying potential variable;

For electrostatics I think it is Potential, sometimes it is AV, or P depends on the solver


Potential Variable Name = String Potential

[raback]

Hi

There is no default names for these. If not given, nothing will be done with those.

The two "condition" keywords are probably rather rarely used. You could, for example, imagine a case where some condition freezes the particle movement. It is not easy to come up with such though...

Note that the "potential" needs to be a nodal field such that its gradient will then be the field causing the force on the particle.

-Peter

[willsprocket]

Hi,

Thank you for the reply.

The following is an attempt to use keywords to initialize 100 particles from a fixed region inside an electrostatic field and track their motion. Are there keywords that I'm missing (except for those that deal with the electrostatic solver) or miss-using? How do these need to be grouped between the equation and solver?

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Number of Particles = 100
Coordinate Initialization Method = sphere random
Initial Sphere Radius = 1e-3
Initial Sphere Center = Size 3; 0.0 1.0 0.0
Velocity Initialization Method = thermal random
Initial Velocity = Size 3; 0.0 1.0 0.0

Timestep Distance = 1e-3
Max Characteristic Speed = True

Particle Particle Collision = False
Particle Particle Contact = False
Box Particle Contact = False
Potential Variable Name = Potential

Particle Mass = 6.7e-27
Particle Radius = 1.4e-10
Particle Gravity = False
Particle Lift = False
Particle Charge = 1.6e-19

Particle To Field = False

Output Interval = 1
Output Format = vtu
Vtu Format = True
Filename Prefix = ions
Scalar Field i = distance
Vector Field i = velocity

Particle Accumulation = True

Thank you,

Will

[willsprocket]

Dumb question:

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Initial Sphere Center Size 3; Real

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Initial Velocity Size n, dim; Real

How are these specified in a XML file for ElmerGUI?

[raback]

Hi

In the XML file the syntax is always "keyword = str" where you cannot change the keyword part. Hence you have to use the old syntax of Elmer to give the size. If you can modify the l.h.s. you would use the prettier

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Initial Sphere Center(3) = 1.0 2.0 3.0

but when l.h.s. is fixed you have to use

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Initial Sphere Center = Size 3; 1.0 2.0 3.0 

And hence the .r.h.s. is now the thing you would set in ElmerGUI.

-Peter

[raback]

Hi,

Maybe you haven't found the consistency tests? They provide a working setup. Cases are very simple and there are only ~800 tests so they are far from exhaustive. Here "elmerfem" is the repo obtained from https://github.com/ElmerCSC/.

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elmeruser@elmeruser-VirtualBox:~/elmerfem/fem/tests$ grep ParticleDynamics * -r | grep Procedure
ParticleFalling/case.sif:  Procedure = "ParticleDynamics" "ParticleDynamics"
ParticleFalling2/case.sif:  Procedure = "ParticleDynamics" "ParticleDynamics"
ParticleFalling3/case.sif:  Procedure = "ParticleDynamics" "ParticleDynamics"
ParticleFallingBlock/case.sif:  Procedure = "ParticleDynamics" "ParticleDynamics"
ParticleHeating/case.sif:  Procedure = "ParticleDynamics" "ParticleDynamics"

-Peter

[willsprocket]

The following keyword listed in the manual isn't recognized by the solver

35ParticleDynamics-p201.PNG (11.8 KiB) Viewed 577 times

How do I couple the electrostatic field with the particle dynamics solver?

I have now looked at the test cases and don't see anything to assist with charged particles in an electrostatic field.

I apologize for all the questions. I'm very eager to make this work and want to learn Elmer as I think it will help with my career.

Regards,

Will

1st Year Engineering Student

[willsprocket]

So keywords Particle Radius and Particle Charge are also not listed in 'SOLVER.KEYWORDS' but are present in the models manual. It seems that contrary to what has been presented, Elmer will not solve charged particle motion in an electrostatic field.

[kevinarden]

For variables not listed in the keywords you only get an error if you do not declare the variable type as a string, real, or integer

in this case
Potential Variable Name = String Potential

Particle Radius would be

Particle Radius = Real 0.01