OpenLB – Open Source Lattice Boltzmann Code Forums on OpenLB General Topics Output of the root-mean-square(rms) velocity in the example of channel3D

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• #5663
yx19971028
Participant

Dear everyone,

// Averages a functor value about a timespan and gives back the averaged value(TA)
// and in 3*Dim the root mean square value(RMS) of the functorvalue in Dim in the operator
// TA = SUM(functorvalue(iT)/SUM(iT))
// RMS = SQRT( SUM( (functorvalue(iT) – TA)^2 / SUM(iT) ) ) on the function in the website
in the website about the superLatticeTimeAveraged3D.h.
I want to ask how to get the root-mean-square(rms) velocity in the example of channel3D.

Regards,
Xu Yang.

#5681
Marc
Participant

Dear Xu Yang,

just check the last three entries of the SuperLatticeTimeAveragedF3D in Paraview, should be your RMS Velocity:

for (int iDim = _sData.getDataSize(); iDim < _sData.getDataSize()*2; iDim++)
if (_sDataP2.get(iCloc,input[1],input[2],input[3],(int) iDim-_sDataP2.getDataSize())/_ensembles – _sData.get(iCloc,input[1],input[2],input[3],(int) iDim-_sDataP2.getDataSize())*_sData.get(iCloc,input[1],input[2],input[3],(int) iDim-_sDataP2.getDataSize())/_ensembles/_ensembles<0) {
output[iDim]=0;
}
else {
output[iDim] = sqrt(_sDataP2.get(iCloc,input[1],input[2],input[3],(int) iDim-_sDataP2.getDataSize())/_ensembles – _sData.get(iCloc,input[1],input[2],input[3],(int) iDim-_sDataP2.getDataSize())*_sData.get(iCloc,input[1],input[2],input[3],(int) iDim-_sDataP2.getDataSize())/_ensembles/_ensembles);
}

Best,
Marc

• This reply was modified 3 years, 2 months ago by Marc.
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