Today , i have a very thorny problem . My model has a parameter was used to predict the binary diffusion coefficient (Dij) at species transport equation . For example Dij = 3.64*e-8* T**2.334*(Pci*Pcj)**0.416*(Tci*Tcj)**-0.48625 {Pci---critical pressure of species i Pcj---critical pressure of species j Tci---critical temperature of species i Tcj---critical temperature of species j } In my model ,five species was be existed indie the model . H2,O2,H2O,CO2,N2 i want to solve the Dij from above equation . so. i also wrote a program of UDF by visual C++ Unfortunately , this program is wrong in FLUENT . Who can assist to modify this thorny program....??? Best regrad to you

Kevin-Chang

DEFINE_PROPERTY(Binary_diffusion,cell,thread) { int i,j; real Dij; if(i==0. || j==1.) { C_DIFF_L(cell,thread,0,1)=3.64e-8*pow(C_T(cell,thread),2.334)*pow((Pc0*Pc1),1/3)*pow((Tc0*Tc1),-0.48625)*((1/M0+1/M1),1/2); /*Laminar species diffusivity */ Dij=C_DIFF_L(cell,thread,0,1); } else if(i==0. || j==2.) { C_DIFF_L(cell,thread,0,2)=3.64e-8*pow(C_T(cell,thread),2.334)*pow((Pc0*Pc2),1/3)*pow((Tc0*Tc2),-0.48625)*((1/M0+1/M2),1/2); /*Laminar species diffusivity */ Dij=C_DIFF_L(cell,thread,0,2); } else if(i==0. || j==3.) { C_DIFF_L(cell,thread,0,3)=3.64e-8*pow(C_T(cell,thread),2.334)*pow((Pc0*Pc3),1/3)*pow((Tc0*Tc3),-0.48625)*((1/M0+1/M3),1/2); /*Laminar species diffusivity */ Dij=C_DIFF_L(cell,thread,0,3); } else if(i==0. || j==4.) { C_DIFF_L(cell,thread,0,4)=3.64e-8*pow(C_T(cell,thread),2.334)*pow((Pc0*Pc4),1/3)*pow((Tc0*Tc4),-0.48625)*((1/M0+1/M4),1/2); /*Laminar species diffusivity */ Dij=C_DIFF_L(cell,thread,0,4); } else { C_DIFF_L(cell,thread,1,2)=3.64e-8*pow(C_T(cell,thread),2.334)*pow((Pc1*Pc2),1/3)*pow((Tc1*Tc2),-0.48625)*((1/M1+1/M2),1/2); /*Laminar species diffusivity */ Dij=C_DIFF_L(cell,thread,1,2); } return Dij;

}

Today , i have a very thorny problem .

My model has a parameter was used to predict the binary diffusion coefficient (Dij) at species transport equation .

For example Dij = 3.64*e-8* T^2.334*(Pci*Pcj)^0.3333*(Tci*Tcj)^-0.48625*(1/Mi+1/Mj)^0.5

{Pci---critical pressure of species i Pcj---critical pressure of species j Tci---critical temperature of species i Tcj---critical temperature of species j }

In my model ,five species was be existed indie the model . H2,O2,H2O,CO2,N2

i want to solve the Dij from above equation . so. i also wrote a program of UDF by visual C++

Unfortunately , this program is wrong in FLUENT . Who can assist to modify this thorny program ??

Best regrad to you

Kevin-Chang

DEFINE_PROPERTY(Binary_diffusion,cell,thread)

{ int i,j;

real Dij;

if(i==0. || j==1.)

{C_DIFF_L(cell,thread,0,1)=3.64e-8*pow(C_T(cell,thread),2.334)*pow((Pc0*Pc1),1/3)*pow((Tc0*Tc1),-0.48625)*((1/M0+1/M1),1/2); /*Laminar species diffusivity */

Dij=C_DIFF_L(cell,thread,0,1); }

else if(i==0. || j==2.)

{C_DIFF_L(cell,thread,0,2)=3.64e-8*pow(C_T(cell,thread),2.334)*pow((Pc0*Pc2),1/3)*pow((Tc0*Tc2),-0.48625)*((1/M0+1/M2),1/2); /*Laminar species diffusivity */

Dij=C_DIFF_L(cell,thread,0,2); }

else if(i==0. || j==3.)

{C_DIFF_L(cell,thread,0,3)=3.64e-8*pow(C_T(cell,thread),2.334)*pow((Pc0*Pc3),1/3)*pow((Tc0*Tc3),-0.48625)*((1/M0+1/M3),1/2); /*Laminar species diffusivity */

Dij=C_DIFF_L(cell,thread,0,3); }

else if(i==0. || j==4.)

{C_DIFF_L(cell,thread,0,4)=3.64e-8*pow(C_T(cell,thread),2.334)*pow((Pc0*Pc4),1/3)*pow((Tc0*Tc4),-0.48625)*((1/M0+1/M4),1/2); /*Laminar species diffusivity */

Dij=C_DIFF_L(cell,thread,0,4); }

else

{C_DIFF_L(cell,thread,1,2)=3.64e-8*pow(C_T(cell,thread),2.334)*pow((Pc1*Pc2),1/3)*pow((Tc1*Tc2),-0.48625)*((1/M1+1/M2),1/2); /*Laminar species diffusivity */ Dij=C_DIFF_L(cell,thread,1,2); }

return Dij; }

why are you defining the diffusion equation 5 for each species? you could use a for loop statement: for (i=1, i<=n, i++)

Dear sir I have a problem with this title. If it's possible for you please send me your received responses. Very thanks for your attention to my request. With the best regards. Mahdi saniee nezhad