If all the nanoparticles could be treated as small spherical particles, then here is a model for you to start::

u: viscosity,  f: volume fraction of suspension

(1) Einstein’s estimation on the effective viscosity of dilute suspensions

u_eff = u(1+2.5f)

I would assume if you don't know the particle size and the influence of your nanoparticles with your fluid, you may not be able to simulate. First, you need to prepare the dispersions (not "suspensions"), and you need to make sure you have fully dispersed nanoparticles. Then, you vbasically only need 3 concentrations to determine the interaction parameter: 0% Cu NP, 0.2 and 0.5% (or whatever is available.

Then you use the equation I have provided here (although it is written for polymer systems, but it is valid for non-polymeric ones as well):

https://www.researchgate.net/publication/252436748_Rheological_Phenomena_and_Structure_Formation_in_Multiphase_Polymer_Systems?ev=srch_pub&_sg=oeJntEDU9FzaHc7idvrQk8zF4t8YVprwfIs6S1sjhxCGdawLMIWb_aonofkTATnb.uTnYJtmFFkdi-RfqLBQTTnw27pBtLHbino2z-l6eninru_NYEDJlVwTK0b0RzGTM.9JqFpviiP0NhaU4FjTA1qtTVWq1G-t1fv9PCjqg5wG6L65jl-ZVlRR4GEcCseKR4

In addition, you might be interested in this:

https://www.researchgate.net/publication/290789681_Turbulent_Mixing_in_Non-Newtonian_Dispersions

Chapter Rheological Phenomena and Structure Formation in Multiphase ...

Conference Paper Turbulent Mixing in Non-Newtonian Dispersions