Thermal Expansion

[mumić]

Hello there!

Latelly I've been messing with some of the properties on GranOO and the last of them was the thermal properties.

Problem is that, when I apply _ThermalExpansion, the simulation kinda "breathes", as shown in the video below.


I didn't find a proper reason for it, it could be I applying it wrongly, but I don't know, I mostly mimicked the code on Thermal examples.

The code for this simulation can be found below. If anyone can pinpoint me the reason for it, thank you a lot!
The agdd file is this one.
There is no stop condition on the code because I'm stopping it manually to check wether if stuff are working or not.

===============================================================================

<?xml version="2.0" encoding="UTF-8" standalone="no"?>
<GranOO Version="2.0" TotIteration="inf" OutDir="expansion" Verbose="No" ThreadNumber="4" > 
  <PreProcessing>
    <PlugIn Id="_ReadDomain" FileName="cube.agdd"/>   
    <PlugIn Id="_SetDensity" Density="4934.9" />
    <PlugIn Id="_InitThermalProperties" Temperature="1000" Cp="2200" Conductivity="10" Set="Boundary" />
    <PlugIn Id="_ThermalExpansion" Alpha="7.2e-6" Set="Global"/>
    <PlugIn Id="_SetElasticProperty" YoungModulus="14e9" PoissonRatio="0.24" CoordNumber="8.0"/>
    <PlugIn Id="_ComputeOptimalTimeStep" Ratio="0.14" />
    <PlugIn Id="_NewTimeStep" Val="1e-2" ID="Thermal" />
  </PreProcessing>
  
  <Processing>
    <PlugIn Id="_Check" />
    <PlugIn Id="_ImposeTemperature" Value="1000-0.01*it" Set="Boundary-xMin"/>
    <PlugIn Id="_ConductHeat" TimeStep="Thermal"/>
    <PlugIn Id="_ThermalExpansion" Alpha="7.2e-6" Set="Global"/>
    <PlugIn Id="_ClearLoad" />
    <PlugIn Id="_ApplyBondLoad"/>
    <PlugIn Id="_IntegrateAcceleration" Linear="Yes" Angular="Yes" BetaLinear="1.3" BetaAngular="1.3"/>
    <PlugIn Id="_ExportToPVD" Field="All" IterLoop="20"/>
  </Processing>
 
  <PostProcessing>
  </PostProcessing>
</GranOO>

[Damien André]

Hello,
Thermal conduction with thermal expansion is a very experimental feature ! Nobody used it seriously... So you experienced some trouble. In my mind, your problem comes from absolute vs relative temperature.

Here, you initialize temperature at "1000". So, at the first time step, you apply a very high thermal expansion from 0 to 1000. It induces vibrations of your domain. So, you must use relative temperature. It gives.

 <?xml version="2.0" encoding="UTF-8" standalone="no"?>
<GranOO Version="2.0" TotIteration="inf" OutDir="expansion" Verbose="No" ThreadNumber="4" > 
  <PreProcessing>
    <PlugIn Id="_ReadDomain" FileName="cube.agdd"/>   
    <PlugIn Id="_SetDensity" Density="4934.9" />
    <PlugIn Id="_InitThermalProperties" Temperature="0" Cp="2200" Conductivity="10" Set="Boundary" />
    <PlugIn Id="_ThermalExpansion" Alpha="7.2e-6" Set="Global"/>
    <PlugIn Id="_SetElasticProperty" YoungModulus="14e9" PoissonRatio="0.24" CoordNumber="8.0"/>
    <PlugIn Id="_ComputeOptimalTimeStep" Ratio="0.14" />
    <PlugIn Id="_NewTimeStep" Val="1e-2" ID="Thermal" />
  </PreProcessing>
  
  <Processing>
    <PlugIn Id="_Check" />
    <PlugIn Id="_ImposeTemperature" Value="-0.01*it" Set="Boundary-xMin"/>
    <PlugIn Id="_ConductHeat" TimeStep="Thermal"/>
    <PlugIn Id="_ThermalExpansion" Alpha="7.2e-6" Set="Global"/>
    <PlugIn Id="_ClearLoad" />
    <PlugIn Id="_ApplyBondLoad"/>
    <PlugIn Id="_IntegrateAcceleration" Linear="Yes" Angular="Yes" BetaLinear="1.3" BetaAngular="1.3"/>
    <PlugIn Id="_ExportToPVD" Field="All" IterLoop="20"/>
  </Processing>
 
  <PostProcessing>
  </PostProcessing>
</GranOO>

I do not test this *.inp. It should work as expected. Cheers, Damien.

[Damien André]

I test it, it seems to work ! :)

[mumić]

Thank you for the reply!
That makes a lot of sense, I should be testing it when I get back to my computer.