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Calculating Capactitance--No Stored Reaction Force data

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I am trying to design a simple parallel plate capacitor model into which I plan to introduce further complications later on for a sensor. Thus far, I have created the model and plotted the electric field, but have not been able to calculate the capacitance.

My model is enclosed in a cylinder of air with two smaller (shorter) cylinders of copper. One is grounded, and one has a terminal voltage of 10V.

Here are my questions/hesitations with my current model (attached):

1. Voltage surface plot seems incorrect and only is plotted on only one surface apparently.

2. E-field lines appear inside of the copper, but not much on the outside. There shouldn't be field lines in the conductor, and I want to be able to see the lines in between the plates.

3. (Most importantly) When I try to calculate the capacitance using the global evaluation, the program yields an error that there is "No Stored Reaction Force data."

Some things I have read in the documentation and this forum suggested to me these things could contribute to the errors:

1. Calculation of reaction forces (I have the box in the solver checked already). Is there an additional parameter/solution I must calculate?

2. I have read things about internal boundaries being messed up if they are within another structure (e.g. my cylinder of air), but haven't seen a solution or an option to turn them on/off in version 4.2.

Thanks for the help--still trying to figure out the nuts and bolts of the program, and sometimes the documentation doesn't answer all of my questions.


1 Reply Last Post 29 mars 2012, 02:49 UTC−4

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Posted: 1 decade ago 29 mars 2012, 02:49 UTC−4
There are two extra "Compile Equations" nodes at the end of the solving sequence in your model. They probably got there by mistake. When I removed them, I could evaluate the global expression for the capacitance.
There are two extra "Compile Equations" nodes at the end of the solving sequence in your model. They probably got there by mistake. When I removed them, I could evaluate the global expression for the capacitance.

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