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Fix mixture entropy/gibbs_energy single-multi scaling mismatches #132

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Fix mixture entropy/gibbs_energy single-multi scaling mismatches #132

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16 changes: 9 additions & 7 deletions source/mixture.f90
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Original file line number Diff line number Diff line change
Expand Up @@ -858,8 +858,8 @@ function mixture_calc_entropy_single(self, weights, temperature, pressure) resul
s = s + nj*(sj - log(nj))
end if
end do
s = s - n*log(pressure/n)
s = s * gas_constant !/ 1.d3
s = s - n*log(pressure/std_pressure/n)
s = s * gas_constant

end function

Expand Down Expand Up @@ -892,11 +892,11 @@ function mixture_calc_entropy_multi(self, weights, temperatures, pressures) resu
s = s + nj*sj
else
n = n + nj
s = s + nj*(sj - log(nj*pressures(j)))
s = s + nj*(sj - log(nj*pressures(j)/std_pressure))
end if
end do
s = s + n*log(n)
s = s * gas_constant / 1.d3
s = s * gas_constant

end function

Expand Down Expand Up @@ -931,24 +931,26 @@ function mixture_calc_gibbs_energy_multi(self, weights, temperatures, pressures)

! Locals
integer :: j
real(dp) :: gj, nj, n, nr, pr
real(dp) :: gj, nj, n, nr, pr, total_weight

call check_array_len(size(weights), self%num_species, 'mixture_calc_gibbs_energy_multi weights')
call check_array_len(size(temperatures), self%num_species, 'mixture_calc_gibbs_energy_multi temperatures')
call check_array_len(size(pressures), self%num_species, 'mixture_calc_gibbs_energy_multi pressures')

total_weight = sum(weights)

! Must pre-compute because cannot factor out of the
! sum when consitituent temperatures can vary.
n = 0.0d0
do j = 1, self%num_species
if (self%is_condensed(j)) cycle
nj = weights(j)/self%species(j)%molecular_weight
nj = weights(j)/self%species(j)%molecular_weight/total_weight
n = n + nj
end do

g = 0.0d0
do j = 1, self%num_species
nj = weights(j)/self%species(j)%molecular_weight
nj = weights(j)/self%species(j)%molecular_weight/total_weight
gj = self%species(j)%calc_gibbs_energy(temperatures(j))
if (self%is_condensed(j)) then
g = g + nj*gj
Expand Down
8 changes: 4 additions & 4 deletions source/mixture_test.pf
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Original file line number Diff line number Diff line change
Expand Up @@ -329,16 +329,16 @@ contains
t = temp(1)
@assertRelativelyEqual(-1.19532599d+07, mix%calc_enthalpy(wtfracs, t), tol)
@assertRelativelyEqual(-1.20517040d+07, mix%calc_energy(wtfracs, t), tol)
!@assertRelativelyEqual(-1.48300159E+07, mix%calc_gibbs_energy(wtfracs, t, p), tol)
!@assertRelativelyEqual( 9.46301312d+03, mix%calc_entropy(wtfracs, t, p), tol)
@assertRelativelyEqual(-1.48300159E+07, mix%calc_gibbs_energy(wtfracs, t, p), tol)
@assertRelativelyEqual( 9.46301312d+03, mix%calc_entropy(wtfracs, t, p), tol)

! Version 2: Allow per-species temperatures and pressures
! This enables fuels and oxidizers to have different initial states
! prior to being mixed and equilibrated.
@assertRelativelyEqual(-1.19532599d+07, mix%calc_enthalpy(wtfracs, temp), tol)
@assertRelativelyEqual(-1.20517040d+07, mix%calc_energy(wtfracs, temp), tol)
!@assertRelativelyEqual(-1.48300159E+07, mix%calc_gibbs_energy(wtfracs, temp, pres), tol)
!@assertRelativelyEqual( 9.46301312d+03, mix%calc_entropy(wtfracs, temp, pres), tol)
@assertRelativelyEqual(-1.48300159E+07, mix%calc_gibbs_energy(wtfracs, temp, pres), tol)
@assertRelativelyEqual( 9.46301312d+03, mix%calc_entropy(wtfracs, temp, pres), tol)

end subroutine

Expand Down
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