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Gas Mixture Properties
Core Numerical Engine in Fortran 90 • 31 total downloads
gas_mixture.f90
! =========================================================================
! Source File: gas_mixture.f90
! =========================================================================
program gas_mixture
implicit none
integer::nsp,iostat_val,i,j,ns
double precision::y(10),MW(10),Cp(10),mu(10),kk(10)
double precision::y_sum,Mmix,Cp_mol,Cp_mass,mu_mix,k_mix
double precision::phi_ij,num,den,R_mix,gamma_mix,rho_STP
double precision::R_gas,y1_sw,mu_sw,k_sw,y_tmp(10)
R_gas=8.314462d0
read(*,*,iostat=iostat_val) nsp
if(iostat_val/=0.or.nsp<2)then;write(*,*)'ERROR: Bad input.';stop;end if
if(nsp>10)nsp=10
do i=1,nsp
read(*,*,iostat=iostat_val) y(i),MW(i),Cp(i),mu(i),kk(i)
if(iostat_val/=0)then;write(*,*)'ERROR: Bad input line',i;stop;end if
end do
y_sum=0.0d0;do i=1,nsp;y_sum=y_sum+y(i);end do
if(y_sum>0)then;do i=1,nsp;y(i)=y(i)/y_sum;end do;end if
Mmix=0;Cp_mol=0
do i=1,nsp;Mmix=Mmix+y(i)*MW(i);Cp_mol=Cp_mol+y(i)*Cp(i);end do
Cp_mass=Cp_mol/Mmix*1000.0d0
R_mix=R_gas/Mmix*1000.0d0
gamma_mix=Cp_mass/(Cp_mass-R_mix)
rho_STP=101325.0d0*Mmix/(R_gas*273.15d0*1000.0d0)
mu_mix=0;k_mix=0
do i=1,nsp
num=y(i)*mu(i); den=0
do j=1,nsp
phi_ij=(1.0d0+sqrt(mu(i)/mu(j))*(MW(j)/MW(i))**0.25d0)**2 &
/sqrt(8.0d0*(1.0d0+MW(i)/MW(j)))
den=den+y(j)*phi_ij
end do
mu_mix=mu_mix+num/max(den,1.0d-30)
end do
do i=1,nsp
num=y(i)*kk(i); den=0
do j=1,nsp
phi_ij=(1.0d0+sqrt(mu(i)/mu(j))*(MW(j)/MW(i))**0.25d0)**2 &
/sqrt(8.0d0*(1.0d0+MW(i)/MW(j)))
den=den+y(j)*phi_ij
end do
k_mix=k_mix+num/max(den,1.0d-30)
end do
write(*,'(A)')'============================================================'
write(*,'(A)')' GAS MIXTURE PROPERTIES (Wilke / Wassilijewa)'
write(*,'(A)')'============================================================'
write(*,*)
write(*,'(A)')'--- INPUTS --------------------------------------------------'
write(*,'(A,I4)') ' Number of Species = ',nsp
write(*,'(A)')' # y_i MW Cp[J/molK] mu[uPa.s] k[W/mK]'
write(*,'(A)')' -----------------------------------------------------------'
do i=1,nsp
write(*,'(I4,2X,F8.4,2X,F8.2,4X,F8.2,4X,F8.2,4X,F8.4)') i,y(i),MW(i),Cp(i),mu(i),kk(i)
end do
write(*,*)
write(*,'(A)')'--- MIXTURE PROPERTIES --------------------------------------'
write(*,'(A,F12.4,A)') ' Molar Mass M_mix = ',Mmix,' g/mol'
write(*,'(A,F12.4,A)') ' Cp_mix (molar) = ',Cp_mol,' J/(mol.K)'
write(*,'(A,F12.2,A)') ' Cp_mix (mass) = ',Cp_mass,' J/(kg.K)'
write(*,'(A,F12.4,A)') ' Viscosity mu_mix = ',mu_mix,' uPa.s'
write(*,'(A,F12.6,A)') ' Conductivity k_mix = ',k_mix,' W/(m.K)'
write(*,'(A,F12.4,A)') ' Gas Constant R_mix = ',R_mix,' J/(kg.K)'
write(*,'(A,F12.4)') ' Gamma (Cp/Cv) approx = ',gamma_mix
write(*,'(A,F12.4,A)') ' Density at STP = ',rho_STP,' kg/m3'
write(*,*)
ns=20
write(*,'(A)')'--- SWEEP: y(1) VARIATION -----------------------------------'
write(*,'(A)')' y(1) mu_mix k_mix'
write(*,'(A)')' -----------------------------------------------------------'
do i=1,ns
y1_sw=dble(i-1)/dble(ns-1)
y_tmp=0;y_tmp(1)=y1_sw
if(nsp>1)then
den=0;do j=2,nsp;den=den+y(j);end do
if(den>0)then;do j=2,nsp;y_tmp(j)=(1.0d0-y1_sw)*y(j)/den;end do
else;y_tmp(2)=1.0d0-y1_sw;end if
end if
mu_sw=0;k_sw=0
do j=1,nsp
num=y_tmp(j)*mu(j);den=0
do ns=1,nsp
phi_ij=(1.0d0+sqrt(mu(j)/mu(ns))*(MW(ns)/MW(j))**0.25d0)**2 &
/sqrt(8.0d0*(1.0d0+MW(j)/MW(ns)))
den=den+y_tmp(ns)*phi_ij
end do
mu_sw=mu_sw+num/max(den,1.0d-30)
end do
do j=1,nsp
num=y_tmp(j)*kk(j);den=0
do ns=1,nsp
phi_ij=(1.0d0+sqrt(mu(j)/mu(ns))*(MW(ns)/MW(j))**0.25d0)**2 &
/sqrt(8.0d0*(1.0d0+MW(j)/MW(ns)))
den=den+y_tmp(ns)*phi_ij
end do
k_sw=k_sw+num/max(den,1.0d-30)
end do
write(*,'(F8.4,4X,F10.4,4X,F10.6)') y1_sw,mu_sw,k_sw
end do
write(*,*)
write(*,'(A)')'--- CORRELATIONS USED ---------------------------------------'
write(*,'(A)')' Wilke (1950): mu_mix = sum(yi*mui / sum(yj*phi_ij))'
write(*,'(A)')' Wassilijewa (1904): k_mix same form with conductivity.'
write(*,'(A)')' phi_ij = [1+sqrt(mui/muj)*(Mj/Mi)^0.25]^2 / sqrt(8(1+Mi/Mj))'
end program gas_mixture
Solver Description
Computes collective ideal gas mixture properties (molecular weight, specific heats, viscosity, conductivity) using Wilke's method and Wassilijewa mixing rules.
Key Numerical Methods & Architecture
- Input Redirection: Reads parameters sequentially from standard input (`stdin`) using Fortran sequential read (`read(*,*)`), ensuring modular integration.
- Modular Design: Formulated using pure mathematical routines, separation of equations from output formatting, and precise numerical solvers (e.g. bisection, Newton-Raphson).
- Standard Compliant: Written in clean, standards-compliant Fortran 90 to ensure cross-compiler compatibility.
🛠️ Local Compilation
To test this code on your machine, compile the source code file(s) using a standard Fortran compiler (e.g., `gfortran`).
Compilation Command:
gfortran -O3 gas_mixture.f90 -o gas_mixture
Execution Command:
Execute the program by feeding the sample input file into the program using stdin redirection:
gas_mixture < input.txt
📥 Downloads & Local Files
Preview of the required input file (input.txt):
! Number of species in mixture (up to 10)
2
! Species 1 mole fraction
0.79
! Species 1 molar mass [g/mol]
28.01
! Species 1 molar heat capacity Cp [J/mol-K]
29.1
! Species 1 dynamic viscosity [uPa-s]
17.8
! Species 1 thermal conductivity [W/m-K]
0.0260
! (Repeat inputs sequentially for each species)
0.21
! Parameter 8
32.00
! Parameter 9
29.4
! Parameter 10
20.6
! Parameter 11
0.0267
2
! Species 1 mole fraction
0.79
! Species 1 molar mass [g/mol]
28.01
! Species 1 molar heat capacity Cp [J/mol-K]
29.1
! Species 1 dynamic viscosity [uPa-s]
17.8
! Species 1 thermal conductivity [W/m-K]
0.0260
! (Repeat inputs sequentially for each species)
0.21
! Parameter 8
32.00
! Parameter 9
29.4
! Parameter 10
20.6
! Parameter 11
0.0267