Function input feature for time-dependent boundary conditions

[kharold23]

Current situation

Closes #89

Release Notes

• Added a new parameter fn to flow and pressure boundary conditions that takes in a string
• Interprets the string as a function of time, represented by the variable t
• The value of the boundary condition is calculated at each time step by evaluating the function at t = the current time value.

Documentation

Time-dependent boundary conditions can now be input using a function passed in as a string. The function is of the variable t, or time. For example:
"bc_values": { "fn": "2.0 * (4*atan(1.)) * COS(2.0 * (4*atan(1.)) * t)" }

Testing

Test case test_time_dependent_block added to test_io.py, which runs json files timeDep_Flow.json and timeDep_Pressure.json.

Code of Conduct & Contributing Guidelines

• I agree to follow the Code of Conduct and Contributing Guidelines.

[ktbolt]

I ran the pulsatileFlow_CStenosis_steadyPressure case on Ubuntu 22 and got the following exception

terminate called after throwing an instance of 'std::runtime_error'
  what():  Maximum number of non-linear iterations reached.

You need to add catching exceptions in the Python testing code.

[ktbolt]

It is very easy for a user to add an incorrect math expression so you need to have a try/catch here and also throw an exception if parser.compile() returns false.

[ktbolt]

We don't want to mix external software with our source code so the exprtk.hpp file should not be in svZeroDSolver/src/. We need to add a ThirdParty directory and put the exprtk.hpp file in a sub-directory of it.

[ktbolt]

Also I see that there is Docker container file in svZeroDSolver/container/profiling for Ubuntu 22, you can use this to test I think.