[Porous Flow] How to use persistent variable Zi for simulations involving more than one fluid component

[batodon]

During single or immiscible multiphase reactive transport simulation involving different fluid components, the geochemistry module provides updated mass fractions to the porous flow module as follows (See the GeoTes simulation, for example):

[massfrac_from_geochem]
  type = MultiAppCopyTransfer
  source_variable = 'massfrac_Na massfrac_Cl massfrac_SiO2'
  variable = 'f0 f1 f2'
  from_multi_app = react
[]

In miscible multiphase reactive transport flow, when we use the persistent variable Zi instead of the mass fraction, how does the persistent variable gets updated for the different components? Do we use three persistent variables (i.e., Zi, Zii, Ziii), each per component in the porous flow module or one suffices? For example:

Different persistent variable Z for each component:

  [massfrac_from_geochem]
    type = MultiAppCopyTransfer
    source_variable = 'massfrac_Na massfrac_Cl massfrac_SiO2'
    variable = 'zi zii ziii'  
    from_multi_app = react
  []

One persistent variable Z for all components:

  [massfrac_from_geochem]
    type = MultiAppCopyTransfer
    source_variable = = 'massfrac_Na massfrac_Cl massfrac_SiO2'
    variable = 'zi zi zi'  
    from_multi_app = react
  []

I ask because I’m getting the following convergence error when I use a different persistent variable, Z, for each component:

  Linear solve did not converge due to DIVERGED_PC_FAILED iterations 0
                 PC failed due to FACTOR_OUTMEMORY
Nonlinear solve did not converge due to DIVERGED_LINE_SEARCH iterations 0
 Solve Did NOT Converge!