Interpolating local velocity and local shear rate

Palabos General
#1

Hi all,

I am running an application using Palabos where I solve for the velocity field using lattice boltzmann method, and use my velocity field as an input to another solver. For this purpose, I need to be able to interpolate between grids, and so I was wondering if Palabos has any inbuilt function to interpolate the local velocity and shear rate at a given point in space within the geometry.

TIA

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Sliding interface
#2

Hello,

just to be sure I understand what you want to do correctly. You want to provide a set of points (on aribitrary positions) and interpolate any value on them? also what should be the order of the interpolation you need?

#3

Thanks orestis for the reply. Yes, that is exactly what I am looking to do.
Any weighted linear interpolation technique should be good enough.

#4

you are welcome.

in the file dataProcessors/dataAnalysisWrapper3D.h you will find a function named

std::vector<Array<T,3> > velocitySingleProbes (
        MultiBlockLattice3D<T,Descriptor>& lattice,
        std::vector<Array<T,3> > const& positions );

This function takes a vector of positions and returns a list of velocities at the given positions performing a trilinear interpolation. Would this be ok for you?

I guess you can inspire yourself by this function and add the shear rate too. Then do not forget to make a merge request and be a happy Palabos contributor :smiley:

If you need any further guidance do not hesitate to ask.

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#5

That is exactly the kind of thing I was looking for. Thanks a lot!

1 Like
#7

Hi orestis,

Please find the link to the code that implements shear stress interpolation using the same interpolation scheme for velocitySingleProbes. Let me know what I have to do to contribute the same to the Palabos library.

Right now, this functional can be implemented simply by including shearStressWrapper3D.h in the main program, along with palabos3D.h

https://github.com/kaushikns/plb_shear.git

#8

Nice!

To contribute first read the contributing instructions.

To summarize, here you should create a fork of Palabos, add your modifications to the relevant files (for example your wrappers should go in dataProcessors/dataAnalysisWrapper3D.h).

Then do a merge request.