## Problem with tutorial 14

The graphical user interface of Elmer
Posts: 9
Joined: 26 Sep 2018, 18:46
Antispam: Yes
Contact:

### Problem with tutorial 14

Hi all,
I am new to this forum as I am new to Elmer. I have been using it for a while now to perform some linear elasticity simultaneous and recently I am trying to simulate electrostatics. I was following the tutorial 14 (Electrostatic equation – Capacitance of perforated plate) but the result is wrong and I can't figure out why.

Here is my .sif:

Code: Select all

``````Header
CHECK KEYWORDS Warn
Mesh DB "." "."
Include Path ""
Results Directory ""
End

Simulation
Max Output Level = 5
Coordinate System = Cartesian
Coordinate Mapping(3) = 1 2 3
Steady State Max Iterations = 1
Output Intervals = 1
Timestepping Method = BDF
BDF Order = 1
Solver Input File = case.sif
Post File = case.ep
Coordinate Scaling = 0.001
End

Constants
Gravity(4) = 0 -1 0 9.82
Stefan Boltzmann = 5.67e-08
Permittivity of Vacuum = 8.8542e-12
Boltzmann Constant = 1.3807e-23
Unit Charge = 1.602e-19
End

Body 1
Target Bodies(1) = 1
Name = "Body 1"
Equation = 1
Material = 1
End

Solver 1
Equation = Result Output
Procedure = "ResultOutputSolve" "ResultOutputSolver"
Output File Name = case
Output Format = Vtu
Exec Solver = Always
End

Solver 2
Equation = Electrostatics
Calculate Electric Energy = True
Calculate Electric Field = True
Variable = Potential
Procedure = "StatElecSolve" "StatElecSolver"
Exec Solver = Always
Stabilize = True
Bubbles = False
Lumped Mass Matrix = False
Optimize Bandwidth = True
Steady State Convergence Tolerance = 1.0e-5
Nonlinear System Convergence Tolerance = 1.0e-7
Nonlinear System Max Iterations = 20
Nonlinear System Newton After Iterations = 3
Nonlinear System Newton After Tolerance = 1.0e-3
Nonlinear System Relaxation Factor = 1
Linear System Solver = Iterative
Linear System Iterative Method = BiCGStab
Linear System Max Iterations = 500
Linear System Convergence Tolerance = 1.0e-10
BiCGstabl polynomial degree = 2
Linear System Preconditioning = Diagonal
Linear System ILUT Tolerance = 1.0e-3
Linear System Abort Not Converged = False
Linear System Residual Output = 1
Linear System Precondition Recompute = 1
End

Equation 1
Name = "Equation 1"
Active Solvers(2) = 1 2
End

Material 1
Name = "Air (room temperature)"
Viscosity = 1.983e-5
Heat expansion Coefficient = 3.43e-3
Heat Conductivity = 0.0257
Relative Permittivity = 1.00059
Sound speed = 343.0
Heat Capacity = 1005.0
Density = 1.205
End

Boundary Condition 1
Target Boundaries(1) = 4
Name = "Ground"
Potential = 0.0
End

Boundary Condition 2
Target Boundaries(4) = 1 2 3 7
Name = "Cap"
Potential = 2.0
End
``````
And this is the log from the solver:

Code: Select all

``````ELMER SOLVER (v 8.2) STARTED AT: 2018/09/26 17:27:34
ParCommInit:  Initialize #PEs:            1
MAIN:
MAIN: =============================================================
MAIN: ElmerSolver finite element software, Welcome!
MAIN: This program is free software licensed under (L)GPL
MAIN: Copyright 1st April 1995 - , CSC - IT Center for Science Ltd.
MAIN: Version: 8.2 (Rev: Release, Compiled: 2016-03-15)
MAIN: =============================================================
MAIN:
MAIN:
MAIN: -------------------------------------

LoadMesh: Scaling coordinates: 1.000E-03 1.000E-03 1.000E-03

LoadMesh: Elapsed time (CPU,REAL):     0.6300    0.6300 (s)

MAIN: -------------------------------------

OptimizeBandwidth: ---------------------------------------------------------
OptimizeBandwidth: Computing matrix structure for: electrostatics...done.
OptimizeBandwidth: Half bandwidth without optimization: 960
OptimizeBandwidth:

OptimizeBandwidth: Bandwidth Optimization ...done.
OptimizeBandwidth: Half bandwidth after optimization: 1468
OptimizeBandwidth: Bandwidth optimization rejected, using original ordering.
OptimizeBandwidth: ---------------------------------------------------------

MAIN:
MAIN: -------------------------------------
MAIN: -------------------------------------
MAIN:
SingleSolver: Attempting to call solver
SingleSolver: Solver Equation string is: result output
ResultOutputSolver: -------------------------------------
ResultOutputSolve: Saving with prefix: case
ResultOutputSolver: Dimension of mesh: 3
ResultOutputSolver: Creating list for saving - if not present
CreateListForSaving: Field Variables for Saving
CreateListForSaving: Scalar Field 1: potential
CreateListForSaving: Scalar Field 2: electric energy density
CreateListForSaving: Vector Field 1: electric field
ResultOutputSolver: Saving in unstructured VTK XML (.vtu) format
VtuOutputSolver: Saving results in VTK XML format with prefix: case
VtuOutputSolver: Saving number of partitions: 1
VtuOutputSolver: Number of geometry nodes to save:   33159
VtuOutputSolver: Number of dof nodes to save:   33159
VtuOutputSolver: Number of elements to save:   36474

ResultOutputSolver: -------------------------------------
SingleSolver: Attempting to call solver
SingleSolver: Solver Equation string is: electrostatics
StatElecSolve: -------------------------------------
StatElecSolve: STATELEC SOLVER:
StatElecSolve: -------------------------------------
StatElecSolve:
StatElecSolve: Electrostatic iteration: 1
StatElecSolve: Starting Assembly...

StatElecSolve:    Assembly:  32 % done

StatElecSolve:    Assembly:  64 % done

StatElecSolve:    Assembly:  96 % done

DefUtils::DefaultDirichletBCs: Setting Dirichlet boundary conditions
DefUtils::DefaultDirichletBCs: Dirichlet boundary conditions set
StatElecSolve:  Assembly (s)          :   3.2009999999999996
1 0.3027E+00
2 0.1705E+00
3 0.1163E+00
4 0.8689E-01
5 0.6855E-01
6 0.5485E-01
7 0.4352E-01
8 0.3449E-01
9 0.2829E-01
10 0.2498E-01
11 0.2238E-01
12 0.2013E-01
13 0.1819E-01

14 0.1652E-01
15 0.1503E-01
16 0.1369E-01
17 0.1255E-01
18 0.1162E-01
19 0.1092E-01
20 0.1032E-01
21 0.9752E-02
22 0.9164E-02
23 0.8584E-02
24 0.8032E-02
25 0.7542E-02
26 0.7121E-02
27 0.6761E-02
28 0.6452E-02
29 0.6223E-02
30 0.6025E-02
31 0.5842E-02
32 0.5669E-02
33 0.5496E-02
34 0.5325E-02
35 0.5156E-02
36 0.4991E-02
37 0.4841E-02
38 0.4689E-02
39 0.4582E-02
40 0.4443E-02
41 0.4390E-02
42 0.4347E-02
43 0.4071E-02

44 0.3904E-02
45 0.3907E-02
46 0.3873E-02
47 0.3513E-02
48 0.3311E-02
49 0.3142E-02
50 0.3144E-02
51 0.2824E-02
52 0.2437E-02
53 0.3306E-02
54 0.2428E-02
55 0.2336E-02
56 0.2264E-02
57 0.1734E-02
58 0.2136E-02
59 0.1881E-02
60 0.1731E-02
61 0.1812E-02
62 0.1820E-02
63 0.1696E-02
64 0.1533E-02
65 0.1410E-02
66 0.1193E-02
67 0.1021E-02
68 0.9107E-03
69 0.7019E-03
70 0.6946E-03
71 0.6482E-03
72 0.4764E-03
73 0.4325E-03

74 0.3432E-02
75 0.2996E-03
76 0.2572E-03
77 0.2930E-03
78 0.2070E-03
79 0.1378E-03
80 0.1347E-03
81 0.1078E-03
82 0.8650E-04
83 0.7075E-04
84 0.3985E-03
85 0.5382E-04
86 0.4750E-04
87 0.2873E-04
88 0.3651E-04
89 0.3647E-04
90 0.3576E-04
91 0.2490E-04
92 0.2301E-04
93 0.3711E-04
94 0.3058E-04
95 0.1243E-04
96 0.1241E-04
97 0.8033E-05
98 0.7024E-05
99 0.4352E-05
100 0.4575E-05
101 0.4409E-05
102 0.3137E-05

103 0.2430E-05
104 0.1566E-05
105 0.9230E-06
106 0.7750E-06
107 0.6698E-06
108 0.4397E-06
109 0.4326E-06
110 0.4244E-06
111 0.9548E-06
112 0.2945E-06
113 0.2921E-06
114 0.2642E-06
115 0.2413E-06
116 0.2403E-06
117 0.2288E-06
118 0.2164E-06
119 0.2106E-06
120 0.1978E-06
121 0.1642E-06
122 0.1391E-06
123 0.1271E-06
124 0.1279E-06
125 0.1225E-06
126 0.1857E-06
127 0.9513E-07
128 0.7831E-07
129 0.7957E-07
130 0.6817E-07
131 0.6771E-07

132 0.5815E-07
133 0.5840E-07
134 0.4723E-07
135 0.4682E-07
136 0.4444E-07
137 0.3663E-07
138 0.3059E-07
139 0.2590E-07
140 0.1955E-07
141 0.8292E-08
142 0.1632E-07
143 0.1033E-07
144 0.1112E-07
145 0.9636E-08
146 0.7126E-08
147 0.6497E-08
148 0.9832E-08
149 0.5409E-08
150 0.4159E-08
151 0.4171E-08
152 0.3091E-08
153 0.2637E-08
154 0.2288E-08
155 0.1853E-08
156 0.1905E-08
157 0.1086E-08
158 0.1027E-08
159 0.1079E-08
160 0.5358E-09
161 0.4295E-09

162 0.2846E-09
163 0.2359E-09
164 0.1600E-09
165 0.1100E-09
166 0.3813E-10
166 0.3813E-10
ComputeChange: NS (ITER=1) (NRM,RELC): (  1.7692182      2.0000000     ) :: electrostatics
StatElecSolve:  Solve (s)             :  0.62300000000000022

StatElecSolve:  Tot. Electric Energy  :   0.0000000000000000
StatElecSolve:  Capacitance           :   0.0000000000000000
StatElecSolve:  Result Norm   :    1.7692181939142007
StatElecSolve:  Relative Change :    2.0000000000000000
StatElecSolve:
StatElecSolve:
StatElecSolve: Electrostatic iteration: 2
StatElecSolve: Starting Assembly...

StatElecSolve:    Assembly:  32 % done

StatElecSolve:    Assembly:  64 % done

StatElecSolve:    Assembly:  96 % done

DefUtils::DefaultDirichletBCs: Setting Dirichlet boundary conditions
DefUtils::DefaultDirichletBCs: Dirichlet boundary conditions set
StatElecSolve:  Assembly (s)          :   3.1980000000000004
1 0.5483E-10
1 0.5483E-10
ComputeChange: NS (ITER=2) (NRM,RELC): (  1.7692182     0.26869305E-09 ) :: electrostatics
StatElecSolve:  Solve (s)             :   1.0999999999999233E-002

StatElecSolve:  Tot. Electric Energy  :   0.0000000000000000
StatElecSolve:  Capacitance           :   0.0000000000000000
StatElecSolve:  Result Norm   :    1.7692181943895773
StatElecSolve:  Relative Change :    2.6869304674967502E-010
StatElecSolve:
ComputeChange: SS (ITER=1) (NRM,RELC): (  1.7692182      2.0000000     ) :: electrostatics
WritePostFile: Saving results in ElmerPost format to file ./case.ep

ElmerSolver: *** Elmer Solver: ALL DONE ***
ElmerSolver: The end
SOLVER TOTAL TIME(CPU,REAL):        21.81       21.81
ELMER SOLVER FINISHED AT: 2018/09/26 17:27:56
``````
I followed the instructions on the tutorial and used the file hexole.grd provided, but still the capacitance is 0 and the total Electric energy is 0. When displaying it in paraview the electric field and the other quantities are simply 0. Any ideas?

I also tried to simply make a parallel plate capacitor using a cube with a volume mesh (I use gmsh for meshing) and I get the same results (I apply a potential between two faces).

I am using ElmerGUI 8.2 under widows 7 professional SP1.

Posts: 9
Joined: 26 Sep 2018, 18:46
Antispam: Yes
Contact:

### Re: Problem with tutorial 14

I found a solution to the problem. It was actually already been seen but hidden in this post:

viewtopic.php?f=3&t=4382

The problem was bug in the 8.2 version, installing the latest nightly build soled the issue, now I get a sensible value for the capacitance and the electric energy.

Hope this helps others as well.