OPM
New formulation for brine viscosity
The old formulation did not account for pressure effects and is thus less accurate The new formulation uses the water viscosity formulation from iapws and correct it for brine using a modifed Jones-Doles equation The formulation and coefficients are based on McBride-Wright 2013 "viscosity and density of aqueous fluids with dissolved CO2"
Shouldn't this be merged?
Maybe, but this time I'm going to insist that the PR be accompanied by actual unit tests which at least provide a minimum of evidence that the revised implementation computes the expected values.
This model gives some improvement compared to data from the previous model by introducing pressure dependency on the viscosity through dependence on pure viscosity from NIST. The deviations are small. The test in test_components that failed pass with 1e-4 as tolerance. i.e. the differences are relatively small. I am still not sure if this PR should go in. I am more concerned about the effect of dissolved CO2 on the viscosity. But I need to dig a bit more to find a good reference model for this. I will make it a draft and come back with more comments later.