TensorFieldBase2D

Palabos General
#1

Hello,

I’m trying to modify the cylinder2d example from the basic openLB install. I would like to modify the last ‘for loop’ to getStrainRate rather than getPressure. I see getPressure is related to scalarField2d while getStrainRate is related to TensorField2d but I can not figure out how to implement the additional argument associated with the functions of TensorFieldBase. Any help with this task would be greatly appreciated.

Thanks

Tim

#2

Hello Tim,

what do you want to do exactly?

Orestis

#3

Ultimately I would like to implement a rheology curve in conjunction with multi-component flow around an obstruction. The upper fluid will have an initial velocity, at some critical point, the lower non-Newtonian fluid will begin to flow. I would like to calculate the strain rate of the lower fluid in order to update its viscosity.

These concepts are new to me and I am trying to practice with the examples by implementing single components of the code I will eventually write.

Thanks

#4

OK. But I’m not sure what you want to do from a technical point of view. What is the problem you are really facing?

#5

Here is the function I’ve modified. The calls associated with ScalarFieldBase work but I can’t get the call to getStrainRate (associated with tensorFieldBase to work.

Here is a portion of the code…

void plotStatistics(BlockStructure2D<T, DESCRIPTOR>& latticeTwo,
BlockStructure2D<T, DESCRIPTOR>& latticeOne, int iT)
{
cout << “Writing Gif\n”;
ImageWriter imageCreator(“leeloo.map”);
imageCreator.writeScaledGif(createFileName(“p”, iT, 6), latticeOne.getDataAnalysis().getPressure());
imageCreator.writeScaledGif(createFileName(“v”, iT, 6), latticeOne.getDataAnalysis().getVelocityNorm());
imageCreator.writeScaledGif<T, 3>(createFileName(“s”, iT, 6), latticeOne.getDataAnalysis().getStrainRate());
}

And the associated error…

In function void plotStatistics(olb::BlockStructure2D<T, olb::descriptors::ForcedShanChenD2Q9Descriptor> &, olb::BlockStructure2D<T, olb::descriptors::ForcedShanChenD2Q9Descriptor>&, int)': rayleighTaylor.cpp:165: error: no matching function for call toolb::graphics::ImageWriter::
writeScaledGif(std::string, const olb::TensorFieldBase2D<T, 3>&)’

Thanks

Tim

#6

Hello,
when you try to write a gif file, you have to write a scalarfield (gif images are 2D). Therefore you have to select a component of you tensor in order to write the file. Something like

latticeOne.getDataAnalysis().getStrainRate().getComponent(0);

#7

Thanks Orestis, that worked. I had to use extractComponenet() and remove the <T, 3> from earlier in the line but I have what I was looking for.

Thanks again

Tim

#8

Hi,

A while back a needed some help creating a gif of strain rate. With the above help I was able to get the GIFs I wanted. I now need to capture the value of strain rate at each node. I’m trying to store the value as a double (gammaDot).

I’ve tried many things but the two below I feel are my best attempts.

I’ve tried
gammaDot = latticeOne.getDataAnalysis().getStrainRate().extractComponent(0);
It returns
error: cannot convert ‘const olb::ScalarFieldBase3D’ to ‘T’ in assignment.

I’ve tried
gammaDot = latticeOne.getDataAnalysis().getStrainRate().get().extractComponent(0);
It returns
error: no matching function for call to ‘olb::TensorFieldBase3D<T, 6>::get() const’

Anyone have any ideas I can try?

Thanks

Tim

#9

Hello,

when you extract one component of the tensorfield you get a scalarfield, then in order to get the value on a given lattice node, you need to “get” it.

Example :

gammaDot = latticeOne.getDataAnalysis().getStrainRate().extractComponent(0).get(iX,iY,iZ);

But you also can simplify that a bit. Get hte tensorfield, the get the tensor on the lattice node, and then get the value of the zeroth component of the tensor.

gammaDot = latticeOne.getDataAnalysis().getStrainRate().get(iX,iY,iZ)[0];

Good luck,
Orestis

#10

That worked great. Thanks again.

Tim