From 24e6b39009f8d43bd1649835a226b6f9107b7989 Mon Sep 17 00:00:00 2001
From: Christophe Geuzaine <cgeuzaine@uliege.be>
Date: Mon, 16 Mar 2020 18:07:10 +0100
Subject: [PATCH] explain both frequency- and time-domain simulation
---
Magnetodynamics/electromagnet.pro | 49 ++++++++++++++++++++++++-------
1 file changed, 39 insertions(+), 10 deletions(-)
diff --git a/Magnetodynamics/electromagnet.pro b/Magnetodynamics/electromagnet.pro
index a693c64..22fdf16 100644
--- a/Magnetodynamics/electromagnet.pro
+++ b/Magnetodynamics/electromagnet.pro
@@ -4,14 +4,18 @@
Features:
- Use of a template formulation library
- Identical to Tutorial 2 for a static current source
- - Frequency-domain solution (phasor) for a dynamic current source
+ - Frequency-domain or time-domain solution for a time-dependent
+ current source
To compute the static solution in a terminal:
getdp electromagnet -solve Magnetostatics2D_a -pos Map_a
- To compute the time-harmonic dynamic solution in a terminal:
+ To compute the frequency-domain solution in a terminal:
getdp electromagnet -solve Magnetodynamics2D_av -pos Map_a
+ To compute the time-dependent dynamic solution in a terminal:
+ getdp electromagnet -setnumber TimeDomain 1 -solve Magnetodynamics2D_av -pos Map_a
+
To compute the solution interactively from the Gmsh GUI:
File > Open > electromagnet.pro
You may choose the Resolution in the left panel:
@@ -42,10 +46,27 @@ Function {
DefineConstant[
murCore = {100, Name "Model parameters/Mur core"},
Current = {0.01, Name "Model parameters/Current"},
- frequency = {1, Name "Model parameters/Frequency"}
+ TimeDomain = {0, Choices{0 = "Frequency-domain", 1 = "Time-domain"},
+ Name "Model parameters/03Analysis type"}
+ frequency = {50, Visible !TimeDomain,
+ Name "Model parameters/Frequency" }
];
- Freq = frequency;
+ If(TimeDomain)
+ // Fix parameters from the "Lib_Magnetodynamics2D_av_Cir.pro" template:
+ Flag_FrequencyDomain = 0;
+ TimeInit = 0; // start simulation at time = 0s
+ TimeFinal = 20e-3; // stop simulation at time = 20 ms
+ DeltaTime = 1e-3; // use time steps equal to 1 ms
+ // Define the time modulation of the current source, i.e. a linear ramp from
+ // 0 to 1 until 10 ms, then a constant value of 1:
+ myModulation[] = ($Time < TimeFinal / 2) ? (2 / TimeFinal * $Time) : 1;
+ Else
+ // Fix parameters from the "Lib_Magnetodynamics2D_av_Cir.pro" template:
+ Flag_FrequencyDomain = 1;
+ Freq = frequency;
+ EndIf
+
mu0 = 4.e-7 * Pi;
nu[ Region[{Air, Ind, AirInf}] ] = 1. / mu0;
nu[ Core ] = 1. / (murCore * mu0);
@@ -55,10 +76,13 @@ Function {
Ns[ Ind ] = 1000 ; // number of turns in coil
Sc[ Ind ] = SurfaceArea[] ; // area of coil cross section
+
// Current density in each coil portion for a unit current (will be multiplied
// by the actual total current in the coil)
- js0[ Ind ] = Ns[]/Sc[] * Vector[0,0,-1];
- CoefGeos[] = 1;
+ js0[ Ind ] = Ns[] / Sc[] * Vector[0, 0, -1];
+
+ // For a correct definition of the voltage:
+ CoefGeos[] = 1; // planar model, 1 meter thick
}
Constraint {
@@ -70,8 +94,13 @@ Constraint {
}
{ Name Current_2D;
Case {
- // represents the phasor amplitude (peak to peak value) for a dynamic analysis
- { Region Ind; Value Current; }
+ If(Flag_FrequencyDomain)
+ // Amplitude of the phasor is set to "Current"
+ { Region Ind; Value Current; }
+ Else
+ // Time-dependent value is set to "Current * myModulation[]"
+ { Region Ind; Value Current; TimeFunction myModulation[]; }
+ EndIf
}
}
{ Name Voltage_2D;
@@ -87,8 +116,8 @@ PostOperation {
{ Name Map_a; NameOfPostProcessing Magnetodynamics2D_av;
Operation {
Print[ a, OnElementsOf Vol_Mag, File "a.pos" ];
- Print[ b, OnElementsOf Vol_Mag, File "b.pos" , HarmonicToTime 20];
- Print[ j, OnElementsOf Vol_Mag, File "j.pos", HarmonicToTime 20];
+ Print[ b, OnElementsOf Vol_Mag, File "b.pos" ];
+ Print[ j, OnElementsOf Vol_Mag, File "j.pos" ];
}
}
}
--
GitLab