Table interpolation using 'time elapsed' (or 'shifted time') value

[caolwec]

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Question

I hope to obtain 'y' values interpolated from a (x, y) table (read in at initial start), where x is the time elapsed from a starting time determined during the calculation. 'x' can be calculated using a postprocessor, but is there a way to use it to get interpolated 'y' values from the (x, y) table.

[GiudGiud]

Hello

I would use the elapsed time as a functor.
Then pass it through an object that will use the functor in lieu of time.
https://mooseframework.inl.gov/source/auxkernels/FunctorCoordinatesFunctionAux.html

now you need a Function that does this. I should have done this instead. I ll make a PR

Guillaume

[GiudGiud]

what is the end goal here? what type of Function and in which object is it being fed?
To make sure that a new Function is actually appropriate

[caolwec]

Hello

I would use the elapsed time as a functor. Then pass it through an object that will use the functor in lieu of time. https://mooseframework.inl.gov/source/auxkernels/FunctorCoordinatesFunctionAux.html

now you need a Function that does this. I should have done this instead. I ll make a PR

Guillaume

Thanks! This works through an Aux variable. You are right - what I need exactly could be just a similar type of 'Function'.

[caolwec]

Thanks for the response! My table of (x, y) data is read in through a 'PiecewiseLinear' function, and the interpolated function value will be used in a 'FunctionAux'.

[GiudGiud]

this already does what you need then.
https://mooseframework.inl.gov/source/auxkernels/FunctorCoordinatesFunctionAux.html

You can use it instead of the FunctionAux
with a postprcoessor as the t_functor, which takes care of doing the time offset, and which you define using a ParsedPostprocessor (expression = t - time_offset)