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"How can I use functions as AC input ?"
Posted Feb 16, 2016, 2:55 p.m. EST Low-Frequency Electromagnetics Version 4.4 1 Reply
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Hello,
I'm trying to run a model of a 3-phase cable in COMSOL 4.4 andi want to study the electric fleld.
I use a 2D , electrostatics model. I have 3 wave forms (each one represents a phase) and i don't know how to use the waveforms in the Electric Potential.
For example, the name of the first waveform is VOLTAGE1 (Angular frequency: 2*pi*50, Phase: 0, Amplitude: 400000 (no units) ).
So, in Electric Potential 1, i select time dependent and in V=1[V]*VOLTAGE1(t[1/s]).
But every time it prints this error:
Failed to evaluate variable.
- Variable: t
- Geometry: 1
- Boundary: 71 72 79 80 155 156 163 164
Failed to evaluate variable.
- Variable: comp1.es.V0
- Defined as: (unit_V_cf*comp1.VOLTAGE1((t/unit_s_cf)))
Failed to evaluate expression.
- Expression: comp1.es.V0-comp1.V
- Feature: Stationary Solver 1 (sol7/s1)
Should I somehow put a variable for t ? If yes, how?
Please help me, i spent so many hours trying to find a solution.
I'm trying to run a model of a 3-phase cable in COMSOL 4.4 andi want to study the electric fleld.
I use a 2D , electrostatics model. I have 3 wave forms (each one represents a phase) and i don't know how to use the waveforms in the Electric Potential.
For example, the name of the first waveform is VOLTAGE1 (Angular frequency: 2*pi*50, Phase: 0, Amplitude: 400000 (no units) ).
So, in Electric Potential 1, i select time dependent and in V=1[V]*VOLTAGE1(t[1/s]).
But every time it prints this error:
Failed to evaluate variable.
- Variable: t
- Geometry: 1
- Boundary: 71 72 79 80 155 156 163 164
Failed to evaluate variable.
- Variable: comp1.es.V0
- Defined as: (unit_V_cf*comp1.VOLTAGE1((t/unit_s_cf)))
Failed to evaluate expression.
- Expression: comp1.es.V0-comp1.V
- Feature: Stationary Solver 1 (sol7/s1)
Should I somehow put a variable for t ? If yes, how?
Please help me, i spent so many hours trying to find a solution.
1 Reply Last Post Feb 17, 2016, 9:52 a.m. EST
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Posted:
9 years ago
The reason is that you use Stationary solver instead of Time-Dependent. When using stationary solver, time is simply not defined. Try to switch to Time-Dependent and see if it solves your problem.