I'm new to Elmer and I'm trying to simulate a copper bar of 0.77x0.04x0.005 m^3 heated by the Joule Effect with a DC of 1kA between two terminals (0.0509 V if we use the resistivity of copper) and BC on all faces over the heat flux with the Heat Transf. Coef. of air 2.5 and a room temperature of 297 K. I'm using the Heat Equation and Static Current Conduction definitions.

I encountered two problems:

- I don't understand the use of "Current Source in the Body Force section for the Static Current Cond.

- The average Joule power simulated between the two terminals is 0.6 W (I think it is in Watts, I've read that the output is in W/m^3, which in that case is worst because...) but if the theoretical value is 15.4 W (conductivity times the square of the electric potential times volume)

Edit:

Thanks to Rich_B to point out that more clarification would be better.

Solver Output:

Code: Select all

```
ELMER SOLVER (v 9.0) STARTED AT: 2022/11/03 14:08:08
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: Webpage http://www.csc.fi/elmer, Email elmeradm@csc.fi
MAIN: Version: 9.0 (Rev: Release, Compiled: 2022-08-02)
MAIN: Running one task without MPI parallelization.
MAIN: Running with just one thread per task.
MAIN: Lua interpreter linked in.
MAIN: =============================================================
MAIN:
MAIN:
MAIN: -------------------------------------
MAIN: Reading Model: case.sif
LoadInputFile: Scanning input file: case.sif
LoadInputFile: Scanning only size info
LoadInputFile: First time visiting
LoadInputFile: Reading base load of sif file
LoadInputFile: Loading input file: case.sif
LoadInputFile: Reading base load of sif file
LoadInputFile: Number of BCs: 3
LoadInputFile: Number of Body Forces: 1
LoadInputFile: Number of Initial Conditions: 0
LoadInputFile: Number of Materials: 1
LoadInputFile: Number of Equations: 1
LoadInputFile: Number of Solvers: 2
LoadInputFile: Number of Bodies: 1
ListTagKeywords: Setting weight for keywords!
ListTagKeywords: No parameters width suffix: normalize by area
ListTagKeywords: Setting weight for keywords!
ListTagKeywords: No parameters width suffix: normalize by volume
ElmerAsciiMesh: Base mesh name: ./.
LoadMesh: Elapsed REAL time: 0.0020 (s)
MAIN: -------------------------------------
AddVtuOutputSolverHack: Adding ResultOutputSolver to write VTU output in file: case
OptimizeBandwidth: ---------------------------------------------------------
OptimizeBandwidth: Computing matrix structure for: static current conduction...done.
OptimizeBandwidth: Half bandwidth without optimization: 440
OptimizeBandwidth:
OptimizeBandwidth: Bandwidth Optimization ...done.
OptimizeBandwidth: Half bandwidth after optimization: 33
OptimizeBandwidth: ---------------------------------------------------------
OptimizeBandwidth: ---------------------------------------------------------
OptimizeBandwidth: Computing matrix structure for: heat equation...done.
OptimizeBandwidth: Half bandwidth without optimization: 440
OptimizeBandwidth:
OptimizeBandwidth: Bandwidth Optimization ...done.
OptimizeBandwidth: Half bandwidth after optimization: 33
OptimizeBandwidth: ---------------------------------------------------------
ElmerSolver: Number of timesteps to be saved: 1
MAIN:
MAIN: -------------------------------------
MAIN: Steady state iteration: 1
MAIN: -------------------------------------
MAIN:
StatCurrentSolve: -------------------------------------
StatCurrentSolve: STAT CURRENT SOLVER:
StatCurrentSolve: -------------------------------------
StatCurrentSolve: Static current iteration: 1
StatCurrentSolve: Assembly (s) : 1.9999999999999948E-003
10 0.2080E-01
20 0.1421E-01
30 0.3656E-02
40 0.1953E-02
50 0.1253E-02
60 0.1058E-02
70 0.3134E-03
80 0.7763E-08
87 0.1545E-10
ComputeChange: NS (ITER=1) (NRM,RELC): ( 0.37093598E-01 2.0000000 ) :: static current conduction
StatCurrentSolve: Solve (s) : 2.0000000000000018E-003
StatCurrentSolve: Total Heating Power : 61135.035330349056
StatCurrentSolve: Effective Resistance : 4.2378482092965332E-008
StatCurrentSolve: Static current iteration: 2
StatCurrentSolve: Assembly (s) : 2.0000000000000018E-003
1 0.1394E-10
ComputeChange: NS (ITER=2) (NRM,RELC): ( 0.37093598E-01 0.44343631E-11 ) :: static current conduction
StatCurrentSolve: Solve (s) : 0.0000000000000000
StatCurrentSolve: Total Heating Power : 61135.035330349041
StatCurrentSolve: Effective Resistance : 4.2378482092965339E-008
ComputeChange: SS (ITER=1) (NRM,RELC): ( 0.37093598E-01 2.0000000 ) :: static current conduction
HeatSolver: Solving the energy equation for temperature
HeatSolve:
HeatSolve:
HeatSolve: -------------------------------------
HeatSolve: TEMPERATURE ITERATION 1
HeatSolve: -------------------------------------
HeatSolve:
HeatSolve: Starting Assembly...
HeatSolve: Assembly:
HeatSolve: Assembly done
10 0.1478E+00
20 0.4493E-02
30 0.1606E-03
40 0.9386E-05
50 0.7312E-08
55 0.3394E-10
ComputeChange: NS (ITER=1) (NRM,RELC): ( 297.18607 2.0000000 ) :: heat equation
HeatSolve: iter: 1 Assembly: (s) 0.01 0.01
HeatSolve: iter: 1 Solve: (s) 0.00 0.00
HeatSolve: Result Norm : 297.18606681252976
HeatSolve: Relative Change : 2.0000000000000000
HeatSolve:
HeatSolve:
HeatSolve: -------------------------------------
HeatSolve: TEMPERATURE ITERATION 2
HeatSolve: -------------------------------------
HeatSolve:
HeatSolve: Starting Assembly...
HeatSolve: Assembly:
HeatSolve: Assembly done
3 0.7256E-10
ComputeChange: NS (ITER=2) (NRM,RELC): ( 297.18607 0.18476890E-11 ) :: heat equation
HeatSolve: iter: 2 Assembly: (s) 0.01 0.03
HeatSolve: iter: 2 Solve: (s) 0.00 0.00
HeatSolve: Result Norm : 297.18606681198065
HeatSolve: Relative Change : 1.8476889986309466E-012
ComputeChange: SS (ITER=1) (NRM,RELC): ( 297.18607 2.0000000 ) :: heat equation
ResultOutputSolver: -------------------------------------
ResultOutputSolver: Saving with prefix: case
ResultOutputSolver: Creating list for saving - if not present
CreateListForSaving: Field Variables for Saving
ResultOutputSolver: Saving in unstructured VTK XML (.vtu) format
VtuOutputSolver: Saving results in VTK XML format with prefix: case
VtuOutputSolver: Saving number of partitions: 1
ResultOutputSolver: -------------------------------------
ElmerSolver: *** Elmer Solver: ALL DONE ***
ElmerSolver: The end
SOLVER TOTAL TIME(CPU,REAL): 0.07 0.07
ELMER SOLVER FINISHED AT: 2022/11/03 14:08:08
```