Describe the bug
Line 253 in JFunctionCapillaryPressure.cpp

GEOS_ERROR_IF( permeability < LvArray::NumericLimits< real64 >::epsilon, "Zero permeability in J-function capillary pressure" );

checks whether permeability is below 64-bit machine precision (~1e-16), but there can be valid permeability values in SI units that may be lower than that. E.g., 0.1 mDarcy = 9.86923e-17 m^2 in Si units. Also, the permeability is not used directly in this function. Instead, sqrt(permeability) is used in the JFunction multiplier. So there is no overflow and this comparison is not necessary.

To Reproduce
Steps to reproduce the behavior:

1. Run a case where some permeability values are of order 0.1 mDarcy = 9.86923e-17 m^2.
2. This will trigger an error "Zero permeability in J-function capillary pressure".

Expected behavior
Permeabilities like those on the order of 0.1 mDarcy are valid and should not trigger an error.

Platform (please complete the following information):

• Machine: Ubuntu 24.04.1 LTS
• Compiler: gcc 14.2.0
• GEOS Version: 1.2.0