Calculate the kinematic mixture pressure in physical
of a given set of elements (sum up all links).

This routine requires initial mole fraction of all species which must
be provided through add_variable table in scheme and set depvar in tracking
for kinematic pressure to the newly added variable.
This will be used to evaluate spatial function for initial mole fraction
from initial mole fraction initial mixture molar density will be computed.
Formula to compute kinematic pressure
here, - species density, \
- species molecular weight ratio, \
- mixture number density,\
- reference density.
Example:
In scheme table,

Description of the method to obtain the variables, here some preset
values might be stored, like the space time function to use or the
required variables.

Number of values to obtain for this variable (vectorized access).

integer,

intent(in)

::

nDofs

Number of degrees of freedom within an element.

real(kind=rk),

intent(out)

::

res(:)

Resulting values for the requested variable.

Linearized array dimension:
(n requested entries) x (nComponents of this variable)
x (nDegrees of freedom)
Access: (iElem-1)fun%nComponentsnDofs +
(iDof-1)*fun%nComponents + iComp

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