Issue50 Inclined boreholes

[MassimoCimmino]

Closes #50.

[MassimoCimmino]

Inclined boreholes are only implemented for the 'detailed' solver, since there is no known 'similarities' or 'equivalent' methods for inclined boreholes.

The initial implementation seems to be working and compares well with Eskilson's results (I will update the issue with figures).

The integral of the FLS solution had to be split between the real and image parts of the solution to avoid overflow flow errors in the product erfc(a*s)*exp(b*s**2) (see the code below). There could be a better implementation for this. It should be explored further before merging.

https://github.com/MassimoCimmino/pygfunction/blob/a847dfd70661f2dbf08e3cbb8f84f093a5b7e00c/pygfunction/heat_transfer.py#L772-L777

While testing the implementation I found that the 'detailed' solver calculates the FLS between a borehole and itself in a for loop, so it is called once per borehole. This could be done in one call for all boreholes at the same time. I will open a new issue to work on this.

[MassimoCimmino]

Remaining tasks:

• [x] Complete docstrings
• [x] Format code
• [x] Merge #191
• [x] Implement tests
• [x] Add an example
• [x] Update field visualization functions to include tilt on horizontal view
• [x] Update CHANGELOG
• [x] Check for more efficient integration approach
• [x] Consider 'similarities' and 'equivalent' implementations (The 'equivalent' solver is moved to #209)
• [x] Approximation for inclined boreholes

[MassimoCimmino]

This is now ready for review.