Feature: Add multidimensional Cp/Ct turbine definition support

[bayc]

Add multidimensional Cp/Ct turbine definition support

This PR adds support for turbine Cp/Ct definitions that depend on an arbitrary number of external variables. This is accomplished by the user supplying Cp/Ct tables for any number of conditions. Interpolants are then created for all the conditions and the interpolant nearest to the defined conditions at the time of computation is selected and used.

Related issue

resolves #619

Impacted areas of the software

Most new code was confined to floris/simulation/turbine_multi_dim.py, with small changes in several other simulation files.

Additional supporting information

Explanation of how to use these new features are included in the example 30_multi_dimensional_cp_ct.py.

To use this functionality, a turbine with a multi-dimensional Cp/Ct definition must be defined, along with multidim_conditions in the flow_field section of the input file. A new solver is used, paired with the multidim_cp_ct velocity deficit model, which used the gch model in its entirety, with some small changes required to down select the correct Ct and power interpolation functions. Examples for all of this are included in 30_multi_dimensional_cp_ct.py.

Currently, the multdim_conditions supplied are considered global and do not support defining local conditions through the farm. The example showcases Cp/Ct values that depend on wave period Tp and wave height Hs, paired with the floating turbine capabilities in FLORIS. Thus, the user must define multidim_conditions for both Tp and Hs. These conditions will then be used internally in a nearest-neighbor selection process to choose the Ct and power interpolants to use.

Test results, if applicable

All tests pass, with an additional unit test added for the multi-dimensional Cp/Ct capbilities, found at tests/turbine_multi_dim_unit_test.py.